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1. eee eee eee cette eee e sees teats en 46 7 13 Packaging package bbclass c occocccnnccnnccononnnnnncnnncnnncnnnnnnnnnnnnnnrnnnrnnnrnnnrrnnrrnnarennnnss 46 7 14 Building Kernels kernel bbclass sssss mmm 47 7 15 Creating Images image bbclass and rootfs bbclass ssseseme 47 7 16 Host System Sanity Checks sanity bbclass ssssssm me 47 7 17 Generated Output Quality Assurance Checks insane bbclass sssesssse 47 7 18 Removing Work Files During the Build rm work bbclass sese 49 7 19 Autotools Configuration Data Cache siteinfo bbclass 0 cece e eee eee teen tees 49 7 20 Adding Users useradd bbclass ssssssssseem mme rennen 49 7 21 Using External Source externalsrc bbclass 00 cece eect eee teeta me 50 7 22 Other Glasses xe o dee ptt eue O eet Leste n o rero Deu 50 B ATE EEE A UR HI MinU i 51 9 Reference Features 4s d tope dene od ta idee veel nde 53 9 1 DISO d nod recto Ded dete I eae d t E e epu a de e Oe Fete e esed 53 sadi 54 FEMME eC 54 9 4 Feature Backfilling esses menm meme nennen ener 55 10 Variables Glossary hei tee LH e ex ote sete tad o ta detent las ex uaa D Det rat pe Feud E ts 57 11 Variable Context oce inesse oi 94 T1 L Configura i ema aids PG EUER ads UMOR UAR DER 94 11 1 1 Distribution Distro ei aretara nain eene emen nennen nennen 94 11 1 2 M chine obere dee Ha c en Oe idee
2. The Yocto Project also includes a site conf sample file that shows how to configure CVS and Git proxy servers if needed 12 15 What s the difference between foo and foo native The native targets are designed to run on the system being used for the build These are usually tools that are needed to assist the build in some way such as quilt native which is used to apply patches The non native version is the one that runs on the target device 12 161 m seeing random build failures Help If the same build is failing in totally different and random ways the most likely explanation is The hardware you are running the build on has some problem You are running the build under virtualization in which case the virtualization probably has bugs The OpenEmbedded build system processes a massive amount of data that causes lots of network disk and CPU activity and is sensitive to even single bit failures in any of these areas True random failures have always been traced back to hardware or virtualization issues 12 17 What do we need to ship for license compliance This is a difficult question and you need to consult your lawyer for the answer for your specific case It is worth bearing in mind that for GPL compliance there needs to be enough information shipped to allow someone else to rebuild and produce the same end result you are shipping This means sharing the source code any patches applied to it and also any configuration in
3. BB DISKMON DIRS BB DISKMON DIRS BB DISKMON DIRS STOPTASKS TMPDIR 1G ABORT TMPDIR 100K The first example works only if you also provide the BB_DISKMON_WARNINTERVAL variable in the conf local conf This ABORT TMPDIR 1G 100K WARN SSTATE DIR 1G example causes the build system to immediately abort when either the disk space in TMPDIR drops below 1 Gbyte or the available free inodes drops below 100 Kbytes Because two directories are provided with the variable the build system also issue a warning when the disk space in the SSTATE DIR directory drops below 1 Gbyte or the number of free inodes drops below 100 Kbytes Subsequent warnings are issued during intervals as defined by the BB_DISKMON_WARNINTERVAL variable The second example stops the build after all currently executing tasks complete when the minimum disk space in the TMPDIR directory drops below 1 Gbyte No disk monitoring occurs for the free inodes in this case The final example immediately aborts the build when the number of free inodes in the TMPDIR directory drops below 100 Kbytes No disk space monitoring for the directory itself occurs in this case BB_DISKMON_WARNINTERVAL Defines the disk space and free inode warning intervals To set these intervals define the variable in your conf local conf file in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory If you are going to use
4. simple example that shows how to add three users and groups to two packages See the useradd example bb for more information on how to use this class 7 21 Using External Source externalsrc bbclass You can use this class to build software from source code that is external to the OpenEmbedded build system In other words your source code resides in an external tree outside of the Yocto Project Building software from an external source tree means that the normal fetch unpack and patch process is not used To use the class you need to define the S variable to point to the directory that contains the source files You also need to have your recipe inherit the externalsrc bbclass class This class expects the source code to support recipe builds that use the B variable to point to the directory in which the OpenEmbedded build system places the generated objects built from the recipes By default the B directory is set to the following which is separate from the Source Directory S WORKDIR BPN PV See the glossary entries for the WORKDIR BPN PV S and B for more information You can build object files in the external tree by setting the B variable equal to S However this practice does not work well if you use the source for more than one variant i e natives such as quilt native or crosses such as gcc cross So be sure there are no native cross or multilib variants of the recipe If you do want
5. 5 3 The Met data meta iecit dende 37 5 3 1 m ta Cldsses ii A ee el tete Puede Pv a vae ope E pe ers 37 5 3 2 MOTAS CONES A a Odo 37 5 3 3 meta conf machine mirii iiion a ai ida nennen nenne trennen nennen nnns 37 5 3 4 meta CconT7dYStEO iiec er o ca eb e per one qud heec gamed 38 5 3 5b meta files scd ea de c decur et A dO eed eet 38 5 3 6 MEA UD oe ERE RI ERR IE UE EE 38 5 3 7 meta recipes DspZ Jie reote OA oe sende pec cues ona 38 5 3 8 meta recipes connectivity oo eee cece cette eee eee eee recat nme nne 38 5 3 9 meta recipes COFGe init teeters A A A dene e eR vue 38 5 3 10 meta recipes devtools sssssssssesesesene eene eene nennen nen nennen 38 5 3 11 meta recipes extended ssssssssssssseseememeee menn mene nnns 38 5 3 12 meta recipes gnOme etel ie eet et savin ene rie aA EEEn EOE de Rog RR EA 38 5 3 13 meta recipes graphics ic0occcoccnnconnconnnnnnncnnnnnnnnnrnnnrrnnnrnnnnnnnnnrrnnrrrnrrrnnrrnnnnn 38 5 314 meta recipes kern6el7 ives i it e er a 38 5 3 15 meta recipessUsbA eiii tae A a AR RAR e ra nca RE nx Ud Rea inus 38 5 3 16 meta recipes multimedia 20 ee eee eee mene nenne nnns 39 5 3 17 meta recipes qt curra A A gr eyes bie A ut dea prx qus 39 5 3 18 meta recipes rt a aaae A A SR XRAME REL ia 39 5 3 19 meta recipes sato oo cence eee eee eee nee a eee ene nnne rhet enn nennen nnn nnn 39 5 3 20 meta recipes SUPpoOrt uiissseectee uomen Enn Ea die Re AR cruore ira
6. Combine this license flag with a whitelist that has the string commercial and you match the flag along with any other flag that starts with the string commercial Under the same circumstances you can use commercial_foo in the whitelist and the build system not only matches commercial foo 1 2 but also matches any license flag with the string commercial foo regardless of the version You can be very specific and use both the package and version parts in the whitelist e g commercial foo 1 2 to specifically match a versioned recipe 3 5 2 2 Other Variables Related to Commercial Licenses Other helpful variables related to commercial license handling exist and are defined in the HOME poky meta conf distro include default distrovars inc file COMMERCIAL AUDIO PLUGINS COMMERCIAL VIDEO PLUGINS COMMERCIAL QT If you want to enable these components you can do so by making sure you have statements similar to the following in your Local conf configuration file COMMERCIAL AUDIO PLUGINS gst plugins ugly mad gst plugins ugly mpegaudioparse COMMERCIAL VIDEO PLUGINS gst plugins ugly mpeg2dec gst plugins ugly mpegstream gst plugins bad mpegvideoparse COMMERCIAL QT qmmp LICENSE FLAGS WHITELIST commercial gst plugins ugly commercial gst plugins bad commercial Of course you could also create a matching whitelist for those components using the more general commercial in the whitelist but that wou
7. LIC FILES CHKSUM The previous example employs the default directory You can also use relative paths as shown in the following example LIC FILES CHKSUM file src ls c beginline 5 endline 16 N md5 bb14ed3c4cda583abc85401304b5cd4e LIC FILES CHKSUM file license html md5 5c94767cedb5d6987c902ac850ded2c6 In this example the first line locates a file in S src ls c The second line refers to a file in WORKDIR which is the parent of S Note that LIC FILES CHKSUM variable is mandatory for all recipes unless the LICENSE variable is set to CLOSED 3 5 1 2 Explanation of Syntax As mentioned in the previous section the LIC FILES CHKSUM variable lists all the important files that contain the license text for the source code It is possible to specify a checksum for an entire file or a specific section of a file specified by beginning and ending line numbers with the beginline and endline parameters respectively The latter is useful for source files with a license notice header README documents and so forth If you do not use the beginline parameter then it is assumed that the text begins on the first line of the file Similarly if you do not use the endline parameter it is assumed that the license text ends with the last line of the file The md5 parameter stores the md5 checksum of the license text If the license text changes in any way as compared to this parameter then a mismatch occurs This mismatch trigg
8. The toolchain configuration is very flexible and customizable It is primarily controlled with the TCMODE variable This variable controls which tcmode inc file to include from the meta conf distro include directory within the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory The default value of TCMODE is default i e tcmode default inc However other patterns are accepted In particular external refers to external toolchains of which there are some basic examples included in the OpenEmbedded Core meta You can use your own custom toolchain definition in your own layer or as defined in the Local conf file at the location conf distro include tcmode inc In addition to the toolchain configuration you also need a corresponding toolchain recipe file This recipe file needs to package up any pre built objects in the toolchain such as libgcc libstdcc any locales and libc An example is the external sourcery toolchain bb which is located in meta recipes core meta within the Source Directory For information on installing and using cross development toolchains see the Installing the ADT and Toolchains http www yoctoproject org docs 1 4 2 adt manual adt manual html installing the adt section in the Yocto Project Application Developer s Guide 12 23How does the OpenEmbedded build system obtain source code and will it work behind my firewall or proxy server The
9. bbdebug 2 Running do my function if exceptional condition then bbnote Hit exceptional condition fi bbdebug 2 Got to point xyz if warning trigger then bbwarn Detected warning trigger this might cause a problem later fi if recoverable error then bberror Hit recoverable error correcting fi if fatal error then bbfatal fatal error detected fi bbdebug 2 Completed do my function 2 3 9 Other Tips Here are some other tips that you might find useful When adding new packages it is worth watching for undesirable items making their way into compiler command lines For example you do not want references to local system files like usr lib or usr include If you want to remove the psplash boot splashscreen add psplash false to the kernel command line Doing so prevents psplash from loading and thus allows you to see the console It is also possible to switch out of the splashscreen by switching the virtual console e g Fn Left or Fn Right on a Zaurus 2 4 Maintaining Build Output Quality Many factors can influence the quality of a build For example if you upgrade a recipe to use a new version of an upstream software package or you experiment with some new configuration options subtle changes can occur that you might not detect until later Consider the case where your recipe is using a newer version of an upstream package In this case a new version of a piece of software might introduce an o
10. docs 1 4 2 dev manual dev manual html build directory during the build By default this directory is named build 5 2 1 build pseudodone This tag file indicates that the initial pseudo binary was created The file is built the first time BitBake is invoked 5 2 2 build conf local conf This file contains all the local user configuration for your build environment If there is no local conf present it is created from local conf sample The local conf file contains documentation on the various configuration options Any variable set here overrides any variable set elsewhere within the environment unless that variable is hard coded within a file e g by using instead of Some variables are hard coded for various reasons but these variables are relatively rare Edit this file to set the MACHINE for which you want to build which package types you wish to use PACKAGE CLASSES the location from which you want to downloaded files DL DIR and how you want your host machine to use resources BB NUMBER THREADS and PARALLEL MAKE 5 2 3 build conf bblayers conf This file defines layers http www yoctoproject org docs 1 4 2 dev manual dev manual html understanding and creating layers which are directory trees traversed or walked by BitBake If bblayers conf is not present it is created from bblayers conf sample when you source the environment setup script The bblayers conf file uses the BBLAYERS variable to list the laye
11. BSP and the machine name you use is different than that used in the kernel KTYPE Defines the kernel type to be used in assembling the configuration The linux yocto recipes define standard tiny and preempt rt kernel types See the Kernel Types http www yoctoproject org docs 1 4 2 kernel dev kernel dev html kernel types section in the Yocto Project Linux Kernel Development Manual for more information on kernel types You define the KTYPE variable in the BSP Descriptions http www yoctoproject org docs 1 4 2 kernel dev kernel dev html bsp descriptions The value you use must match the value used for the LINUX_KERNEL_TYPE value used by the kernel recipe L LAYERDEPENDS LAYERDIR LAYERVERSION LIC FILES CHKSUM LICENSE LICENSE PATH Lists the layers that this recipe depends upon separated by spaces Optionally you can specify a specific layer version for a dependency by adding it to the end of the layer name with a colon e g anotherlayer 3 to be compared against LAYERVERSION anotherlayer in this case An error will be produced if any dependency is missing or the version numbers do not match exactly if specified This variable is used in the conf layer conf file and must be suffixed with the name of the specific layer e g LAYERDEPENDS mylayer When used inside the layer conf configuration file this variable provides the path of the current layer This variable is not available outside of layer conf
12. Feature Backfilling section for more information The long name of the distribution Alias names used for the recipe in various Linux distributions See the Handling a Package Name Alias http www yoctoproject org docs 1 4 2 dev manual dev manual html usingpoky configuring DISTRO_PN_ALIAS section in the Yocto Project Development Manual for more information the version of the distribution DISTROOVERRIDES This variable lists overrides specific to the current distribution By default the variable list includes the value of the DISTRO variable You can extend the variable to apply any variable overrides you want as part of the distribution and are not already in OVERRIDES through some other means DL_DIR The central download directory used by the build process to store downloads You can set this directory by defining the DL_DIR variable in the conf local conf file This directory is self maintaining and you should not have to touch it By default the directory is downloads in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory DL_DIR TOPDIR downloads To specify a different download directory simply uncomment the line and provide your directory During a first build the system downloads many different source code tarballs from various upstream projects Downloading can take a while particularly if your network connection is slow Tarballs are all stored in the
13. For additional information on distributions that support the Yocto Project see the Distribution Support https wiki yoctoproject org wiki Distribution_Support wiki page 1 3 2 Required Packages for the Host Development System The list of packages you need on the host development system can be large when covering all build scenarios using the Yocto Project This section provides required packages according to Linux distribution and function 1 3 2 1 Ubuntu The following list shows the required packages by function given a supported Ubuntu Linux distribution Essentials Packages needed to build an image on a headless system sudo apt get install gawk wget git core diffstat unzip texinfo Y build essential chrpath Graphical Extras Packages recommended if the host system has graphics support sudo apt get install libsdl1 2 dev xterm Documentation Packages needed if you are going to build out the Yocto Project documentation manuals sudo apt get install make xsltproc docbook utils fop ADT Installer Extras Packages needed if you are going to be using the Application Development Toolkit ADT Installer http www yoctoproject org docs 1 4 2 adt manual adt manual html using the adt installer sudo apt get install autoconf automake libtool libglib2 0 dev 1 3 2 2 Fedora Packages The following list shows the required packages by function given a supported Fedora Linux distribution Essentials Packages n
14. Specifies the list of locales to install into the image during the root filesystem construction process The OpenEmbedded build system automatically splits locale files which are used for localization into separate packages Setting the IMAGE_LINGUAS variable ensures that any locale packages that correspond to packages already selected for installation into the image are also installed Here is an example IMAGE LINGUAS pt br de de In this example the build system ensures any Brazilian Portuguese and German locale files that correspond to packages in the image are installed i e locale pt br and locale de de as well as locale pt and locale de since some software packages only provide locale files by language and not by country specific language Defines a multiplier that the build system applies to the initial image size for cases when the multiplier times the returned disk usage value for the image is greater than the sum of IMAGE ROOTFS SIZE and IMAGE ROOTFS EXTRA SPACE The result of the multiplier applied to the initial image size creates free disk space in the image as overhead By default the build process uses a multiplier of 1 3 forthis variable This default value results in 3096 free disk space added to the image when this method is used to determine the final generated image size You should be aware that post install scripts and the package management system uses disk space inside this overhead area Consequently t
15. and references are expanded immediately when parsing of the file completes Optionally specifies the version of a layer as a single number You can use this within LAYERDEPENDS for another layer in order to depend on a specific version of the layer This variable is used in the conf layer conf file and must be suffixed with the name of the specific layer e g LAYERVERSION mylayer Checksums of the license text in the recipe source code This variable tracks changes in license text of the source code files If the license text is changed it will trigger a build failure which gives the developer an opportunity to review any license change This variable must be defined for all recipes unless LICENSE is set to CLOSED For more information see the Tracking License Changes section The list of source licenses for the recipe Follow these rules Do not use spaces within individual license names Separate license names using pipe when there is a choice between licenses Separate license names using amp ampersand when multiple licenses exist that cover different parts of the source You can use spaces between license names Here are some examples LICENSE LGPLv2 1 GPLv3 LICENSE MPL 1 amp LGPLv2 1 LICENSE GPLv2 The first example is from the recipes for Qt which the user may choose to distribute under either the LGPL version 2 1 or GPL version 3 The second example is from Cairo where two licenses
16. anotherpkg conf was added sbin anotherpkg was added installed package names txt anotherpkg was added Changes to images qemux86 64 eglibc core image minimal installed package names txt anotherpkg was added packages qemux86 64 poky linux v86d PACKAGES added v86d extras PR changed from rO to rl PV changed from 0 1 10 to 0 1 12 packages qemux86 64 poky linux v86d v86d PKGSIZE changed from 110579 to 144381 30 PR changed from rO to r1 PV changed from 0 1 10 to 0 1 12 To see changes to the build history using a web interface follow the instruction in the README file here http git yoctoproject org cgit cgit cgi buildhistory web Using the Yocto Project Here is a sample screenshot of the interface e Buildhistory Mozilla Firefox Firefox Bhuildhistary Warning item Summary packages amv Ble poky linux gnueabicaira caire dev ADEPENOS removed ib 11 Aimar added like i i Status Action Required Reviewed by paule on Oct 8 2012 11 51 p m 0 minutes ago Description P packages armv5te noky linux gnueabi cairo cairo dev RDEPEHDS removed I ihxli trim dev added l1ibx11 de Lin rene Resolve Ignore Comments paula Oot 9 2012 11 51 p m 0 minutes ago we feed to determine if this is legit Post a comment Prosi 15 Chapter 3 Technical Details This chapter provides technical details for various parts of the Yocto Project Currently topics
17. basehash The following statements effectively result in a list of global variable dependency excludes variables never included in any checksum BB_HASHBASE WHITELIST TMPDIR FILE PATH PWD BB_TASKHASH BBPATH BB HASHBASE WHITELIST DL DIR SSTATE DIR THISDIR FILESEXTRAPATHS BB HASHBASE WHITELIST FILE DIRNAME HOME LOGNAME SHELL TERM USER BB HASHBASE WHITELIST FILESPATH USERNAME STAGING DIR HOST STAGING DIR TARGET The previous example actually excludes WORKDIR since it is actually constructed as a path within TMPDIR which is on the whitelist The rules for deciding which hashes of dependent tasks to include through dependency chains are more complex and are generally accomplished with a Python function The code in meta lib oe sstatesig py shows two examples of this and also illustrates how you can insert your own policy into the system if so desired This file defines the two basic signature generators OE Core uses OEBasic and OEBasicHash By default there is a dummy noop signature handler enabled in BitBake This means that behavior is unchanged from previous versions OE Core uses the OEBasicHash signature handler by default through this setting in the bitbake conf file BB SIGNATURE HANDLER OEBasicHash The OEBasicHash BB SIGNATURE HANDLER is the same as the OEBasic version but adds the task hash to the stamp files This results in any Metadata http www yoctoproject org docs 1 4 2 dev manual dev ma
18. dev manual dev manual html git repository Note Enabling build history increases your build times slightly particularly for images and increases the amount of disk space used during the build You can disable build history by removing the previous statements from your conf local conf file However you should realize that enabling and disabling build history in this manner can change the do_package task checksums which if you are using the OEBasicHash signature generator the default for many current distro configurations including DISTRO poky and DISTRO and will result in the packaging tasks being re run during the subsequent build To disable the build history functionality without causing the packaging tasks to be re run add this statement to your conf local conf file BUILDHISTORY FEATURES 2 4 2 Understanding What the Build History Contains Build history information is kept in TMPDIR buildhistory in the Build Directory The following is an example abbreviated listing de buildhistory a images E atom pc mU eglibc igi core image minimal A build id depends dot depends nokernel dot depends nokernel nolibc dot depends nokernel nolibc noupdate dot depends nokernel nolibc noupdate nomodules dot files in image txt image info txt installed package names txt installed package sizes txt installed packages txt packages Y ra core2 poky linux EE busy
19. directory defined by DL_DIR and the build system looks there first to find source tarballs Note When wiping and rebuilding you can preserve this directory to speed up this part of subsequent builds You can safely share this directory between multiple builds on the same development machine For additional information on how the build process gets source files when working behind a firewall or proxy server see this specific question in the FAQ 100 chapter E ENABLE_BINARY_LOCALE_GENERATION l l Variable that controls which locales for eglibc are generated during the build useful if the target device has 64Mbytes of RAM or less EXTENDPE Used with file and pathnames to create a prefix for a recipe s version based on the recipe s PE value If PE is set and greater than zero for a recipe EXTENDPE becomes that value e g if PE is equal to 1 then EXTENDPE becomes 1_ If a recipe s PE is not set the default or is equal to zero EXTENDPE becomes See the STAMP variable for an example EXTRA_IMAGE_FEATURES The list of additional features to include in an image Typically you configure this variable in your local conf file which is found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory Although you can use this variable from within a recipe best practices dictate that you do not Note To enable primary features from within the image recipe use the IMAG
20. example that contains both an explicit recipe name and version after variable expansion LICENSE FLAGS license PN PV In order for a component restricted by a LICENSE FLAGS definition to be enabled and included in an image it needs to have a matching entry in the global LICENSE FLAGS WHITELIST variable which is a variable typically defined in your local conf file For example to enable the HOME poky meta recipes multimedia gstreamer gst plugins ugly package you could add either the string commercial_gst plugins ugly or the more general string commercial to LICENSE FLAGS WHITELIST See the License Flag Matching section for a full explanation of how LICENSE FLAGS matching works Here is the example LICENSE FLAGS WHITELIST commercial gst plugins ugly Likewise to additionally enable the package built from the recipe containing LICENSE FLAGS license PN PV and assuming that the actual recipe name was emgd 1 10 bb the following string would enable that package as well as the original gst plugins ugly package LICENSE FLAGS WHITELIST commercial gst plugins ugly license emgd 1 10 As a convenience you do not need to specify the complete license string in the whitelist for every package you can use an abbreviated form which consists of just the first portion or portions of the license string before the initial underscore character or characters A partial string will match any license that contains the given s
21. from the image if you delete them they will not be automatically re created when you build the image again If you do accidentally delete files here you will need to force them to be re created In order to do that you will need to know the target that produced them For example these commands rebuild and re create the kernel files bitbake c clean virtual kernel bitbake virtual kernel 5 2 15 build tmp deploy ipk This directory receives ipk packages produced by the build process 5 2 16 build tmp sysroots This directory contains shared header files and libraries as well as other shared data Packages that need to share output with other packages do so within this directory The directory is subdivided by architecture so multiple builds can run within the one Build Directory 5 2 17 build tmp stamps This directory holds information that BitBake uses for accounting purposes to track what tasks have run and when they have run The directory is sub divided by architecture package name and version Following is an example stamps all poky linux distcc config 1 0 r0 do build 2fdd 2do Although the files in the directory are empty of data BitBake uses the filenames and timestamps for tracking purposes 5 2 18 build tmp log This directory contains general logs that are not otherwise placed using the package s WORKDIR Examples of logs are the output from the check pkg or distro check tasks Running a build does
22. include Yocto Project components shared state sstate cache x32 and Licenses 3 1 Yocto Project Components The BitBake task executor together with various types of configuration files form the OpenEmbedded Core This section overviews these by describing what they are used for and how they interact BitBake handles the parsing and execution of the data files The data itself is of various types Recipes Provides details about particular pieces of software Class Data Abstracts common build information e g how to build a Linux kernel Configuration Data Defines machine specific settings policy decisions and so forth Configuration data acts as the glue to bind everything together For more information on data see the Yocto Project Terms http www yoctoproject org docs 1 4 2 dev manual dev manual html yocto project terms section in the Yocto Project Development Manual BitBake knows how to combine multiple data sources together and refers to each data source as a layer For information on layers see the Understanding and Creating Layers http www yoctoproject org docs 1 4 2 dev manual dev manual html understanding and creating layers section of the Yocto Project Development Manual Following are some brief details on these core components For more detailed information on these components see the Source Directory Structure chapter 3 1 1 BitBake BitBake is the tool at the heart of the OpenEmbedded build
23. including dependency graphs so you can see why something was pulled into the image If you are just interested in this information and not interested in collecting history or any package information you can enable writing only image information without any history by adding the following to your conf local conf file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory INHERIT buildhistory BUILDHISTORY COMMIT 0 BUILDHISTORY FEATURES image 2 4 2 4 Build History SDK Information Build history collects similar information on the contents of SDKs e g meta toolchain or bitbake c populate sdk imagename as compared to information it collects for images The following list shows the files produced for each SDK files in sdk txt A list of files in the SDK with permissions owner group size and symlink information This list includes both the host and target parts of the SDK sdk info txt A text file containing name value pairs with information about the SDK See the following listing example for more information The following information appears under each of the host and target directories for the portions of the SDK that run on the host and on the target respectively depends dot Dependency graph for the SDK that is compatible with graphviz installed package names txt A list of installed packages by name only installed package sizes txt A list o
24. is merged into a shared directory tree such as the sysroot The Yocto Project team has tried to keep the details of the implementation hidden in sstate bbclass From a user s perspective adding shared state wrapping to a task is as simple as this do_deploy example taken from do deploy bbclass DEPLOYDIR WORKDIR deploy PN SSTATETASKS do deploy do deploy sstate name deploy do deploy sstate inputdirs DEPLOYDIR do deploy sstate outputdirs DEPLOY DIR _IMAGE python do deploy setscene sstate setscene d addtask do deploy setscene In the example we add some extra flags to the task a name field deploy an input directory where the task sends data and the output directory where the data from the task should eventually be copied We also adda setscene variant of the task and add the task name to the SSTATETASKS list If you have a directory whose contents you need to preserve you can do this with a line like the following do package sstate plaindirs PKGD PKGDEST This method as well as the following example also works for multiple directories do package sstate inputdirs PKGDESTWORK SHLIBSWORKDIR do package sstate outputdirs PKGDATA DIR SHLIBSDIR do package sstate lockfile PACKAGELOCK These methods also include the ability to take a lockfile when manipulating shared state directory structures since some cases are sensitive to file additions or rem
25. local configuration through the local conf file DISTRO MACHINE DL DIR BBFILES EXTRA IMAGE FEATURES PACKAGE CLASSES BB NUMBER THREADS BBINCLUDELOGS ENABLE BINARY LOCALE GENERATION 11 2 Recipes The following subsections provide lists of variables whose context is recipes required dependencies path and extra build information 11 2 1 Required This section lists variables that are required for recipes LICENSE LIC FILES CHKSUM SRC URI used in recipes that fetch local or remote files 11 2 2 Dependencies This section lists variables that define recipe dependencies DEPENDS RDEPENDS RRECOMMENDS RCONFLICTS RREPLACES 11 2 3 Paths This section lists variables that define recipe paths WORKDIR eS FILES 11 2 4 Extra Build Information This section lists variables that define extra build information for recipes e EXTRA OECMAKE EXTRA OECONF EXTRA OEMAKE PACKAGES DEFAULT PREFERENCE Chapter 12 FAQ 12 1 12 2 12 3 12 4 12 5 How does Poky differ from OpenEmbedded http www openembedded org The term Poky http www yoctoproject org docs 1 4 2 dev manual dev manual html poky refers to the specific reference build system that the Yocto Project provides Poky is based on OE Core http www yoctoproject org docs 1 4 2 dev manual dev manual html oe core and BitBake http www yoctoproject org docs 1 4 2 dev manual dev m
26. more details on how to use the Yocto Project 2 1 Running a Build This section provides a summary of the build process and provides information for less obvious aspects of the build process For general information on how to build an image using the OpenEmbedded build system see the Building an Image http www yoctoproject org docs 1 4 2 yocto project qs yocto project qs html building image section of the Yocto Project Quick Start 2 1 1 Build Overview The first thing you need to do is set up the OpenEmbedded build environment by sourcing the environment setup script as follows source oe init build env lt build dir gt The build dir is optional and specifies the directory the OpenEmbedded build system uses for the build the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory If you do not specify a Build Directory it defaults to build in your current working directory Acommon practice is to use a different Build Directory for different targets For example build x86 for a qemux86 target and build arm for a qemuarm target See the oe init build env section for more information on this script Once the build environment is set up you can build a target using bitbake lt target gt The target is the name of the recipe you want to build Common targets are the images in meta recipes core images meta recipes sato images etc all found in the Source Directory
27. not necessarily mean this directory is created 5 2 19 build tmp pkgdata This directory contains intermediate packaging data that is used later in the packaging process For more information see the Packaging package bbclass section 5 2 20 build tmp work This directory contains architecture specific work sub directories for packages built by BitBake All tasks execute from the appropriate work directory For example the source for a particular package is unpacked patched configured and compiled all within its own work directory Within the work directory organization is based on the package group and version for which the source is being compiled as defined by the WORKDIR It is worth considering the structure of a typical work directory As an example consider linux yocto kernel 3 0 on the machine qemux86 built within the Yocto Project For this package a work directory of tmp work qemux86 poky linux linux yocto 3 0 gitl lt gt referred to as the WORKDIR is created Within this directory the source is unpacked to Linux qemux86 standard build and then patched by Quilt See the Using a Quilt Flow http www yoctoproject org docs 1 4 2 dev manual dev manual html using a quilt workflow section in the Yocto Project Development Manual for more information Within the Linux qemux86 standard build directory standard Quilt directories linux 3 0 patches and linux 3 0 pc are created and standard Quilt commands can be
28. of the bitbake conf file and you will note that even local conf is loaded from there While bitbake conf sets up the defaults you can often override these by using the local conf file machine file or the distribution configuration file 5 3 3 meta conf machine This directory contains all the machine configuration files If you set MACHINE qemux86 the OpenEmbedded build system looks for a qemux86 conf file in this directory The include directory contains various data common to multiple machines If you want to add support for a new machine to the Yocto Project look in this directory 5 3 4 meta conf distro The contents of this directory controls any distribution specific configurations For the Yocto Project the defaultsetup conf is the main file here This directory includes the versions and the SRCDATE definitions for applications that are configured here An example of an alternative configuration might be poky bleeding conf Although this file mainly inherits its configuration from Poky 5 3 5 meta files This directory contains common license files and several text files used by the build system The text files contain minimal device information and lists of files and directories with knows permissions 5 3 6 meta lib This directory contains OpenEmbedded Python library code used during the build process 5 3 7 meta recipes bsp This directory contains anything linking to specific hardware or hardware confi
29. overrides any DEFAULT_ PREFERENCE setting DEFAULT_ PREFERENCE is often used to mark newer and more experimental package versions until they have undergone sufficient testing to be considered stable In summary BitBake has created a list of providers which is prioritized for each target 6 3 Dependencies Each target BitBake builds consists of multiple tasks such as fetch unpack patch configure and compile For best performance on multi core systems BitBake considers each task as an independent entity with its own set of dependencies Dependencies are defined through several variables You can find information about variables BitBake uses in the BitBake documentation which is found in the bitbake doc manual directory within the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory At a basic level it is sufficient to know that BitBake uses the DEPENDS and RDEPENDS variables when calculating dependencies 6 4 The Task List Based on the generated list of providers and the dependency information BitBake can now calculate exactly what tasks it needs to run and in what order it needs to run them The build now starts with BitBake forking off threads up to the limit set in the BB_NUMBER_THREADS variable BitBake continues to fork threads as long as there are tasks ready to run those tasks have all their dependencies met and the thread threshold has not been exceeded It is worth noting
30. resulting from a kernel build Separates files for different machines such that you can build for multiple target machines using the same output directories See the STAMP variable for an example A string identifying the host distribution Strings consist of the host distributor ID followed by the release as reported by the lsb release tool or as read from etc 1lsb release For example when running a build on Ubuntu 12 10 the value is Ubuntu 12 10 If this information is unable to be determined the value resolves to Unknown This variable is used by default to isolate native shared state packages for different distributions e g to avoid problems with glibc version incompatibilities Additionally the variable is checked against SANITY TESTED DISTROS if that variable is set Controls how the OpenEmbedded build system spawns interactive terminals on the host development system e g using the BitBake command with the c devshell command line option For more information see the Using a Development Shell http www yoctoproject org docs 1 4 2 dev manual dev manual html platdev appdev devshell section in the Yocto Project Development Manual You can use the following values for the OE_TERMINAL variable auto gnome xfce rxvt screen konsole none Note Konsole support only works for KDE 3 x Also auto is the default behavior for OE TERMINAL P The recipe name and version P is comprised of the following P
31. so that the path used by BitBake before the mirror substitution is appended to the path used to access the mirror Here is an example SSTATE_MIRRORS file http someserver tld share sstate PATH 4 1 1 2 bblayers conf The meta yocto layer consists of two parts that correspond to the Poky reference distribution and the reference hardware Board Support Packages BSPs respectively meta yocto and meta yocto bsp When running BitBake or Hob for the first time after upgrading your conf bblayers conf file will be updated to handle this change and you will be asked to re run or restart for the changes to take effect 4 1 2 Recipes Differences include changes for the following Python function whitespace proto in SRC_URI nativesdk Task recipes IMAGE FEATURES Removed recipes 4 1 2 1 Python Function Whitespace All Python functions must now use four spaces for indentation Previously an inconsistent mix of spaces and tabs existed which made extending these functions using append or prepend complicated given that Python treats whitespace as syntactically significant If you are defining or extending any Python functions e g populate packages do unpack do patch and so forth in custom recipes or classes you need to ensure you are using consistent four space indentation 4 1 2 2 proto in SRC_URI Any use of proto in SRC URI needs to be changed to protocol In particular this applies to the following UR
32. system and is responsible for parsing the Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata generating a list of tasks from it and then executing those tasks To see a list of the options BitBake supports use the following help command bitbake help The most common usage for BitBake is bitbake lt packagename gt where packagename is the name of the package you want to build referred to as the target in this manual The target often equates to the first part of a bb filename So to run the matchbox desktop 1 2 3 bb file you might type the following bitbake matchbox desktop Several different versions of matchbox desktop might exist BitBake chooses the one selected by the distribution configuration You can get more details about how BitBake chooses between different target versions and providers in the Preferences and Providers section BitBake also tries to execute any dependent tasks first So for example before building matchbox desktop BitBake would build a cross compiler and eglibc if they had not already been built Note This release of the Yocto Project does not support the glibc GNU version of the Unix standard C library By default the OpenEmbedded build system builds with eglibc A useful BitBake option to consider is the k or continue option This option instructs BitBake to try and continue processing the job as much as possible even after encountering an error Whe
33. that you can greatly speed up the build time by properly setting the BB_NUMBER_THREADS variable See the Building an Image http www yoctoproject org docs 1 4 2 yocto project qs yocto project qs html building image section in the Yocto Project Quick Start for more information As each task completes a timestamp is written to the directory specified by the STAMP variable On subsequent runs BitBake looks within the build tmp stamps directory and does not rerun tasks that are already completed unless a timestamp is found to be invalid Currently invalid timestamps are only considered on a per bb file basis So for example if the configure stamp has a timestamp greater than the compile timestamp for a given target then the compile task would rerun Running the compile task again however has no effect on other providers that depend on that target This behavior could change or become configurable in future versions of BitBake Note Some tasks are marked as nostamp tasks No timestamp file is created when these tasks are run Consequently nostamp tasks are always rerun 6 5 Running a Task Tasks can either be a shell task or a Python task For shell tasks BitBake writes a shell script to WORKDIR temp run do taskname pid and then executes the script The generated shell script contains all the exported variables and the shell functions with all variables expanded Output from the shell script goes to the file WORKDIR temp lo
34. the BB_DISKMON WARNINTERVAL variable you must also use the BB_DISKMON_DIRS variable and define its action as WARN During the build subsequent warnings are issued each time disk space or number of free inodes further reduces by the respective interval If you do not provide a BB_DISKMON_WARNINTERVAL variable and you do use BB DISKMON DIRS with the WARN action the disk monitoring interval defaults to the following BB DISKMON WARNINTERVAL 50M 5K When specifying the variable in your configuration file use the following form BB DISKMON WARNINTERVAL disk space interval gt lt disk inode inte where disk space interval is An interval of memory expressed in either G M or K for Gbytes Mbytes or Kbytes respectively You cannot use GB MB or KB disk inode interval is An interval of free inodes expressed in either G M or K for Gbytes Mbytes or Kbytes respectively You cannot use GB MB or KB Here is an example BB DISKMON DIRS WARN SSTATE DIR 1G 100K BB DISKMON WARNINTERVAL 50M 5K These variables cause the OpenEmbedded build system to issue subsequent warnings each time the available disk space further reduces by 50 Mbytes or the number of free inodes further reduces by 5 Kbytes in the SSTATE_DIR directory Subsequent warnings based on the interval occur each time a respective interval is reached beyond the initial warning i e 1 Gbytes and 100 Kbytes BBCLASSEXTEND Allows yo
35. the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory 2 3 8 1 Logging With Python When creating recipes using Python and inserting code that handles build logs keep in mind the goal is to have informative logs while keeping the console as silent as possible Also if you want status messages in the log use the debug loglevel Following is an example written in Python The code handles logging for a function that determines the number of tasks needed to be run python do listtasks bb debug 2 Starting to figure out the task list if noteworthy condition bb note There are 47 tasks to run bb debug 2 Got to point xyz if warning trigger bb warn Detected warning trigger this might be a problem later if recoverable error bb error Hit recoverable error you really need to fix this if fatal_error bb fatal fatal_error detected unable to print the task list bb plain The tasks present are abc bb debug 2 Finished figuring out the tasklist 2 3 8 2 Logging With Bash When creating recipes using Bash and inserting code that handles build logs you have the same goals informative with minimal console output The syntax you use for recipes written in Bash is similar to that of recipes written in Python described in the previous section Following is an example written in Bash The code logs the progress of the do my function function do my function
36. the first question the build system detects changes in the inputs to a given task by creating a checksum or signature of the task s inputs If the checksum changes the system assumes the inputs have changed and the task needs to be rerun For the second question the shared state sstate code tracks which tasks add which output to the build process This means the output from a given task can be removed upgraded or otherwise manipulated The third question is partly addressed by the solution for the second question assuming the build system can fetch the sstate objects from remote locations and install them if they are deemed to be valid Note The OpenEmbedded build system does not maintain PR information as part of the shared state packages Consequently considerations exist that affect maintaining shared state feeds For information on how the OpenEmbedded works with packages and can track incrementing PR information see the Incrementing a Package Revision Number http www yoctoproject org docs 1 4 2 dev manual dev manual html incrementing a package revision number section The rest of this section goes into detail about the overall incremental build architecture the checksums signatures shared state and some tips and tricks 3 2 1 Overall Architecture When determining what parts of the system need to be built BitBake uses a per task basis and does not use a per recipe basis You might wonder why using a per task basis
37. which is specified within meta conf distro defaultsetup conf Specifies a list of distro specific packages to add to all images This variable takes affect through packagegroup base so the variable only really applies to the more full featured images that include packagegroup base You can use this variable to keep distro policy out of generic images As with all other distro variables you set this variable in the distro conf file DISTRO EXTRA RRECOMMENDSSpecifies a list of distro specific packages to add to all images if the DISTRO FEATURES DISTRO FEATURES BACKFILL packages exist The packages might not exist or be empty e g kernel modules The list of packages are automatically installed but you can remove them The features enabled for the distribution For a list of supported features that ship with the Yocto Project see the Distro section Features to be added to DISTRO FEATURES if not also present in DISTRO FEATURES BACKFILL CONSIDERED This variable is set in the meta conf bitbake conf file It is not intended to be user configurable It is best to just reference the variable to see which distro features are being backfilled for all distro configurations See the Feature backfilling section for more information DISTRO_FEATURES_BACKFILL_CG amp auieREBom DISTRO FEATURES BACKFILL that should not be DISTRO NAME DISTRO PN ALIAS DISTRO VERSION backfilled i e added to DISTRO FEATURES during the build See the
38. wiki yoctoproject org wiki BuildingOnRHEL4 Wiki page 12 121 see lots of 404 responses for files on http www yoctoproject org sources Is something wrong Nothing is wrong The OpenEmbedded build system checks any configured source mirrors before downloading from the upstream sources The build system does this searching for both source archives and pre checked out versions of SCM managed software These checks help in large installations because it can reduce load on the SCM servers themselves The address above is one of the default mirrors configured into the build system Consequently if an upstream source disappears the team can place sources there so builds continue to work 12 131 have machine specific data in a package for one machine only but the package is being marked as machine specific in all cases how do prevent this Set SRC URI OVERRIDES PACKAGE ARCH 0 in the bb file but make sure the package is manually marked as machine specific for the case that needs it The code that handles SRC URI OVERRIDES PACKAGE ARCH is in the meta classes base bbclass file 12 141 m behind a firewall and need to use a proxy server How do do that Most source fetching by the OpenEmbedded build system is done by wget and you therefore need to specify the proxy settings in a wgetrc file in your home directory Here are some example settings http proxy http proxy yoyodyne com 18023 ftp proxy http proxy yoyodyne com 18023
39. A ER ERA Yr 17 ALI CASOS MEI 17 3 1 4 Configura toM ree ce a ai 17 3 2 Shared State Cache x osea decr deuda ete oper ce Renee ii atada 17 3 21 Overall Architecture c ue te cete qe e ode ER c qe Reb 18 3 2 2 Checksums SighatU res eius ced certe rer e a a a e en he ne a a nad 18 3 2 3 Shared State c ad eaa oM REL EUREN Ir FOYER e i CE tdg 19 3 2 4 i Tips and IrieKs 22 omi st eu eo aa ee ee Sus 21 BES cM rr 21 Lac ESIB 0 0101 E DX ai Sea vale Ris A neds ia deus Gauge dese banced Plage dette udder rods 22 3 3 2 Stabilizing and Completing X32 0 00 cece cece eset emnes 22 3 3 3 Using X32 Right NOW ps aa IR 22 re MAUI E E 22 3 4 1 SUDDOFL crore o recen a ve ce Te pea rod a reet an a pa pee opea ero di dang anu a Andee dads 23 3 4 2 Enabling Wayland in an Image ssssssmmnm nen 23 3 4 3 Running Weston sssssssssssrsressnsttsrtsttstttt ttt attt ntau urunu n ENRE hee nen nne nnne rennen 23 ECMUMIIACIIC EMT 24 3 5 1 Tracking License Changes occoocccnccnncconnconncnnnnncnnnrnnnrnnnrrnnnnnnnnnnnnnrrrnrrrnrrrnnrnaninn 24 3 5 2 Enabling Commercially Licensed Recipes sssss een eeaeeeaeeeaeeeas 25 4 Migrating to a Newer Yocto Project Release 0 tee tere eee eter aerate nee nennen 28 4 1 Moving to the Yocto Project 1 3 Release sssssssseeme memes 28 4 1 1 Local Configuration uno ri erae ede ead ine EE e de eh Vea de eta a 28 41 2 RECIPES ie x EN EHE RO EOS AM
40. ALLOW EMPTY pkg preinst pkg postinst pkg prerm and pkg postrm and reports if there are variable sets that are not package specific Using these variables without a package suffix is bad practice and might unnecessarily complicate dependencies of other packages within the same recipe or have other unintended consequences xorg driver abi Checks that all packages containing Xorg drivers have ABI dependencies The xserver xorg recipe provides driver ABI names All drivers should depend on the ABI versions that they have been built against Driver recipes that include xorg driver input inc or xorg driver video inc will automatically get these versions Consequently you should only need to explicitly add dependencies to binary driver recipes libexec Checks if a package contains files in usr libexec This check is not performed if the libexecdir variable has been set explicitly to usr libexec staticdev Checks for static library files a in non staticdev packages la Checks la files for any TMPDIR paths Any la file containing these paths is incorrect since libtool adds the correct sysroot prefix when using the files automatically itself desktop Runs the desktop file validate program against any desktop files to validate their contents against the specification for desktop files Note You can use the WARN QA and ERROR QA variables to control the behavior of these checks at the global level i e in your custom distro configura
41. CRIPTION Enable SMP The machine as known by the kernel Sometimes the machine name used by the kernel does not match the machine name used by the OpenEmbedded build system For example the machine name that the OpenEmbedded build system understands as qemuarm goes by a different name in the Linux Yocto kernel The kernel understands that machine as arm_versatile926ejs For cases like these the KMACHINE variable maps the kernel machine name to the OpenEmbedded build system machine name Kernel machine names are initially defined in the Yocto Linux Kernel s meta branch From the meta branch look in the meta cfg kernel cache bsp bsp name bsp name lt kernel type gt scc file For example from the meta branch in the linux yocto 3 0 kernel the meta cfg kernel cache bsp cedartrail cedartrail standard scc file has the following define KMACHINE cedartrail define KTYPE standard define KARCH i386 include ktypes standard branch cedartrail include cedartrail scc You can see that the kernel understands the machine name for the Cedar Trail Board Support Package BSP as cedartrail If you look in the Cedar Trail BSP layer in the meta intel Source Repositories http www yoctoproject org docs 1 4 2 dev manual dev manual html source repositories at meta cedartrail recipes kernel linux linux yocto 3 0 bbappend you will find the following statements among others COMPATIBLE MACHINE cedartrail cedartrail KMACHINE ceda
42. EE CRISE ena eee da fp cee nse ter dee dee 28 4 2 Moving to the Yocto Project 1 4 Release 20 0 cece cece eee e tees eee emere 30 4 2 1 BitBake pii eI tes ot teet XT RE Ree EHE see leant E EGEAS E DE TREE LOL RR 30 4 2 2 Build Behavior irc a o repre oe sd 30 4 2 3 Proxies and Fetching Source ec meme mene mener 30 4 2 4 Custom Interfaces File netbase change ssssseeeee mmm 30 4 2 5 Remote Debugging ccc cce cence eee eee eter ee een emen nnnm nre nee nnne nnn nn 30 LAS ALI lc 31 4 2 7 Target Package Management with RPM ssssssee mee 31 4 2 9 Recipes MOV e eR CREE AERE EE he Lae nen A PERS daaa 31 4 2 9 Removals and Renames aasit i ad a Ea AA nana nana eee enn nnne 31 5 Source Directory Str ctule 25 1 e PER POR TU ERR HE EXE GRE Re a ex eda EEUU dE aay 33 5 1 Top Level Core Components ccc eee eee eee nennen nne nenne nennen 33 Bed Les Dit A pube ueni iE 33 5 2 DUTTA AE 33 5 1 3 documentation coder vt dni rx EE ee ana NAR X RM UE DH ERN Eod EYES Aus 33 2 1 4 AT A AO O E enr Am sume PEN Er une ATA aes 33 5 1 5 meta VOCtO isset TO 34 5 1 6 meta yocto bsp eee e e aded e oda 34 51 7 meta horita p nep anu os 34 5 1 8 meta skeleton il Aids 34 51 9 SCE1DtS rede e ete eie cene EE ded ee ebd E ep IRA e re decus 34 5 1 10 0e init b ild enwv iue try sur Vanes Prae enia FAR Eee xe 34 5 1 11 LICENSE README and README
43. E_FEATURES variable Here are some examples of features you can add dbg pkgs Adds dbg packages for all installed packages including symbol information for debugging and EXTRA_IMAGEDEPENDS EXTRA_OECMAKE EXTRA_OECONF EXTRA_OEMAKE F FILES profiling debug tweaks Makes an image suitable for development For example ssh root access has a blank password You should remove this feature before you produce a production image dev pkgs Adds dev packages for all installed packages This is useful if you want to develop against the libraries in the image read only rootfs Creates an image whose root filesystem is read only See the Creating a Read Only Root Filesystem http www section in the Yocto Project Development Manual for more information tools debug Adds debugging tools such as gdb and strace tools profile Adds profiling tools such as oprofile exmap lttng and valgrind x86 only tools sdk Adds development tools such as gcc make pkgconfig and so forth tools testapps Adds useful testing tools such as ts print aplay arecord and so forth For a complete list of image features that ships with the Yocto Project see the Images section For an example that shows how to customize your image by using this variable see the Customizing Images Using Custom IMAGE FEATURES and EXTRA IMAGE FEATURES http www yoctoproject org docs 1 4 2 dev manual dev manual html usingp
44. GL support Weston 1 0 3 will not run directly on the emulated QEMU hardware However this version of Weston will run under X emulation without issues 3 4 2 Enabling Wayland in an Image To enable Wayland you need to enable it to be built and enable it to be included in the image 3 4 2 1 Building To cause Mesa to build the wayland egl platform and Weston to build Wayland with Kernel Mode Setting KMS https wiki archlinux org index php Kernel Mode Setting support include the wayland flag in the DISTRO FEATURES statement in your local conf file DISTRO FEATURES append wayland Note If X11 has been enabled elsewhere Weston will build Wayland with X11 support 3 4 2 2 Installing To install the Wayland feature into an image you must include the following CORE IMAGE EXTRA INSTALL statement in your local conf file CORE IMAGE EXTRA INSTALL wayland weston 3 4 3 Running Weston To run Weston inside X11 enabling it as described earlier and building a Sato image is sufficient If you are running your image under Sato a Weston Launcher appears in the Utility category Alternatively you can run Weston through the command line interpretor CLI which is better suited for development work To run Weston under the CLI you need to do the following after your image is built 1 Run these commands to export XDG RUNTIME DIR mkdir p tmp USER weston chmod 0700 tmp USER weston export XDG RUNTIME DIR tmp USER w
45. Git repository Typically you could add a specific server for the build system to attempt before any others by adding something like the following to the local conf configuration file in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory PREMIRRORS prepend git http ww yoctoproject org sources An ftp http www yoctoproject org sources An http http ww yoctoproject org sources n https http ww yoctoproject org sources An These changes cause the build system to intercept Git FTP HTTP and HTTPS requests and direct them to the http sources mirror You can use file URLs to point to local directories or network shares as well PRINC Causes the PR variable of bbappend files to dynamically increment This increment minimizes the impact of layer ordering In order to ensure multiple bbappend files can co exist PRINC should be self referencing This variable defaults to 0 Following is an example that increments PR by two PRINC int PRINC 2 It is advisable not to use strings such as 1 with the variable because this usage is very sensitive to layer ordering You should avoid explicit assignments as they cannot adequately represent multiple bbappend files PROVIDES A list of aliases that a recipe also provides These aliases are useful for satisfying dependencies of other recipes during the build as
46. Is e svn bzr e hg e osc Other URIs were already using protocol This change improves consistency 4 1 2 3 nativesdk The suffix nativesdk is now implemented as a prefix which simplifies a lot of the packaging code for nativesdk recipes All custom nativesdk recipes and any references need to be updated to use nativesdk instead of nativesdk 4 1 2 4 Task Recipes Task recipes are now known as Package groups and have been renamed from task bb to packagegroup bb Existing references to the previous task names should work in most cases as there is an automatic upgrade path for most packages However you should update references in your own recipes and configurations as they could be removed in future releases You should also rename any custom task recipes to packagegroup and change them to inherit packagegroup instead of task as well as taking the opportunity to remove anything now handled by packagegroup bbclass such as providing dev and dbg packages setting LIC FILES CHKSUM and so forth See the Package Groups packagegroup bbclass section for further details 4 1 2 5 IMAGE FEATURES Image recipes that previously included apps console core in IMAGE FEATURES should now include splash instead to enable the boot up splash screen Retaining apps console core will still include the splash screen but generates a warning The apps x11 core and apps x11 games IMAGE FEATURES features have be
47. N PV PACKAGE_ARCH The architecture of the resulting package or packages PACKAGE_BEFORE_PN Enables easily adding packages to PACKAGES before PN so that the packages can pick up files that would normally be included in the default package PACKAGE_CLASSES This variable which is set in the local conf configuration file found in the conf folder of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory specifies the package manager to use when packaging data You can provide one or more arguments for the variable with the first argument being the package manager used to create images PACKAGE CLASSES package rpm package deb package ipk For information on build performance effects as a result of the package manager use see Packaging package bbclass in this manual PACKAGE EXTRA ARCHS Specifies the list of architectures compatible with the device CPU This variable is useful when you build for several different devices that use miscellaneous processors such as XScale and ARM926 EJS PACKAGECONFIG This variable provides a means of enabling or disabling features of a recipe on a perrecipe basis The PACKAGECONFIG variable itself specifies a space separated list of the features to enable The features themselves are specified as flags on the PACKAGECONFIG variable You can provide up to four arguments which are separated by commas to determine the behavior of each feature wh
48. PM emulation bluetooth Hardware has integrated BT ext2 Hardware HDD or Microdrive irda Hardware has Irda support keyboard Hardware has a keyboard pci Hardware has a PCI bus pcmcia Hardware has PCMCIA or CompactFlash sockets screen Hardware has a screen serial Hardware has serial support usually RS232 touchscreen Hardware has a touchscreen usbgadget Hardware is USB gadget device capable usbhost Hardware is USB Host capable wifi Hardware has integrated WiFi 9 3 Images The contents of images generated by the OpenEmbedded build system can be controlled by the IMAGE FEATURES and EXTRA IMAGE FEATURES variables that you typically configure in your image recipes Through these variables you can add several different predefined packages such as development utilities or packages with debug information needed to investigate application problems or profile applications Current list of IMAGE FEATURES contains the following dbg pkgs Installs debug symbol packages for all packages installed in a given image dev pkgs Installs development packages headers and extra library links for all packages installed in a given image doc pkgs Installs documentation packages for all packages installed in a given image nfs server Installs an NFS server read only fsroot Creates an image whose root filesystem is read only See the Creating a Read Only Root Filesystem http www yoctoproject org d
49. TDIR variable 7 3 Alternatives update alternatives bbclass This class helps the alternatives system when multiple sources provide the same command This situation occurs when several programs that have the same or similar function are installed with the same name For example the ar command is available from the busybox binutils and elfutils packages The update alternatives bbclass class handles renaming the binaries so that multiple packages can be installed without conflicts The ar command still works regardless of which packages are installed or subsequently removed The class renames the conflicting binary in each package and symlinks the highest priority binary during installation or removal of packages To use this class you need to define a number of variables These variables list alternative commands needed by a package provide pathnames for links default links for targets and so forth For details on how to use this class see the comments in the update alternatives bbclass http git yoctoproject org cgit cgit cgi poky tree meta classes update alternatives bbclass Note You can use the update alternatives command directly in your recipes However this class simplifies things in most cases 7 4 Initscripts update rc d bbclass This class uses update rc d to safely install an initialization script on behalf of the package The OpenEmbedded build system takes care of details such as making sure the script is stopped
50. Wayland http en wikipedia org wiki Wayland_ display_server_protocol Weston is a computer display server protocol that when implemented provides a method for compositing window managers to communicate directly with applications and video hardware and expects them to communicate with input hardware using other libraries Using Wayland with supporting targets can result in better control over graphics frame rendering than an application might otherwise achieve The Yocto Project provides the Wayland protocol libraries and the reference Weston compositor as part of it release This section describes what you need to do to implement Wayland and use the compositor when building an image for a supporting target 3 4 1 Support The Wayland protocol libraries and the reference Weston compositor ship as integrated packages in the meta layer of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory Specifically you can find the recipes that build both Wayland and Weston at meta recipes graphics wayland You can build both the Wayland and Weston packages for use only with targets that accept the Mesa 3D and Direct Rendering Infrastructure http dri freedesktop org wiki which is also known as Mesa DRI This implies that you cannot build and use the packages if your target uses for example the Intel Embedded Media and Graphics Driver Intel EMGD that overrides Mesa DRI Note Dueto lack of E
51. Yocto Project The Yocto Project development team makes the Yocto Project available through a number of methods Releases Stable tested releases are available through http downloads yoctoproject org releases yocto Nightly Builds These releases are available at http autobuilder yoctoproject org nightly These builds include Yocto Project releases meta toolchain tarball installation scripts and experimental builds Yocto Project Website You can find releases of the Yocto Project and supported BSPs at the Yocto Project website http www yoctoproject org Along with these downloads you can find lots of other information at this site 1 5 Development Checkouts Development using the Yocto Project requires a local Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory You can set up the Source Directory by downloading a Yocto Project release tarball and unpacking it or by cloning a copy of the upstream Poky http www yoctoproject org docs 1 4 2 dev manual dev manual html poky Git repository For information on both these methods see the Getting Set Up http www yoctoproject org docs 1 4 2 dev manual dev manual html getting setup section in the Yocto Project Development Manual Chapter 2 Using the Yocto Project This chapter describes common usage for the Yocto Project The information is introductory in nature as other manuals in the Yocto Project documentation set provide
52. You can select eglibc or uclibc Note This release of the Yocto Project does not support the glibc implementation of libc The toolchain selector This variable replaces POKYMODE which is no longer supported The TCMODE variable selects the external toolchain built using the OpenEmbedded build system or a few supported combinations of the upstream GCC or CodeSourcery Labs toolchain The variable identifies the tcmode files used in the meta conf distro include directory which is found in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory By default TCMODE is set to default which chooses the tcmode default inc file The variable is similar to TCLIBC which controls the variant of the GNU standard C library Libc used during the build process eglibc or uclibc The directory in which the file BitBake is currently parsing is located Do not manually set this variable This variable is the temporary directory the OpenEmbedded build system uses when it does its work building images By default the TMPDIR variable is named tmp within the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory If you want to establish this directory in a location other than the default you can uncomment the following statement in the conf local conf file in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual ht
53. a ct e teenies 94 11 1 3 zEOCal A ert aL Diver eves eese eA y ceca Deui pepe reca 94 11 2 Reclp6s tore ea E eie t M Va eR O O 95 A A eret een RU A LAN Md LEE 95 11 2 2 Dependenties 2 enitn iia ER DERE UU e seeds bans Shaded stay 95 12 RCHEL HLAR EP 95 11 2 4 Extra Build Information sssssssseeeeme emen enne 95 12 A tu see diese seuss O 96 13 Contributing to the Yocto Project ersteren epaia EAE E Raa Ea ENA 102 13 1 INtrOdUCtION LE 102 13 2 racking BUGS rot a rd Ea we ies 102 133 Mailing SS ai iO eii 102 13 4 Internet Relay Chat IRG curiosa eee eo ako ines non veces atte geo ERR DE EORR U BAR RUN ERRE e regla 102 TSS LINKS aaa a EE 102 13 6 Gontrib tlons aiii a a 103 Chapter 1 Introduction 1 1 Introduction This manual provides reference information for the current release of the Yocto Project The Yocto Project is an open source collaboration project focused on embedded Linux developers Amongst other things the Yocto Project uses the OpenEmbedded build system which is based on the Poky project to construct complete Linux images You can find complete introductory and getting started information on the Yocto Project by reading the Yocto Project Quick Start http www yoctoproject org docs 1 4 2 yocto project qs yocto project qs html For task based information using the Yocto Project see the Yocto Project Development Manual http www yoctoproject org docs 1 4 2 dev manual dev manual html and t
54. able points to a directory were BitBake places temporary files which consist mostly of task logs and scripts when building a particular recipe The variable is typically set as follows T WORKDIR temp The WORKDIR is the directory into which BitBake unpacks and builds the recipe The default bitbake conf file sets this variable The T variable is not to be confused with the TMPDIR variable which points to the root of the directory tree where BitBake places the output of an entire build TARGET_ARCH The architecture of the device being built The OpenEmbedded build system supports the following architectures arm mips TARGET_CFLAGS TARGET_FPU TARGET_OS TCLIBC TCMODE THISDIR TMPDIR TOPDIR ppc x86 x86 64 Flags passed to the C compiler for the target system This variable evaluates to the same as CFLAGS Specifies the method for handling FPU code For FPU less targets which include most ARM CPUs the variable must be set to soft If not the kernel emulation gets used which results in a performance penalty Specifies the target s operating system The variable can be set to linux for eg libc based systems and to linux uclibc for uclibc For ARM EABI targets there are also linux gnueabi and linux uclibc gnueabi values possible Specifies which variant of the GNU standard C library libc to use during the build process This variable replaces POKYLIBC which is no longer supported
55. adds sound support to the qemux86 machine Add netfilter to all linux yocto kernels KERNEL FEATURES features netfilter Add sound support to the qemux86 machine KERNEL FEATURES append _qemux86 cfg sound The type of kernel to build for a device usually set by the machine configuration files and defaults to zImage This variable is used when building the kernel and is passed to make as the target to build The location of the kernel sources This variable is set to the value of the STAGING KERNEL DIR within the module bbclass class For information on how this variable is used see the Incorporating Out of Tree Modules http www yoctoproject org docs 1 4 2 kernel dev kernel dev html incorporating out of tree modules section The KERNEL_SRC variable is identical to the KERNEL_PATH variable The location of the kernel sources This variable is set to the value of the STAGING KERNEL DIR within the module bbclass class For information on how this variable is used see the Incorporating Out of Tree Modules http www yoctoproject org docs 1 4 2 kernel dev kernel dev html incorporating out of tree modules section The KERNEL_PATH variable is identical to the KERNEL_SRC variable Provides a short description of a configuration fragment You use this variable in the scc file that describes a configuration fragment file Here is the variable used in a file named smp scc to describe SMP being enabled define KFEATURE DES
56. age controlling variables you must use this variable in conjunction with a package name override Here is an example RREPLACES PN other package being replaced RSUGGESTS A list of additional packages that you can suggest for installation by the package manager at the time a package is installed Not all package managers support this functionality As with all package controlling variables you must always use this variable in conjunction with a package name override Here is an example RSUGGESTS PN useful package another package S The location in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory where unpacked package source code resides This location is within the working directory WORKDIR which is not static The unpacked source location depends on the package name PN and package version PV as follows WORKDIR PN PV As an example assume a Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual htmlz source directory top level folder named poky and a default Build Directory at poky build In this case the working directory the build system uses to build the db package is the following poky build tmp work qemux86 poky Linux db 5 1 19 r3 db 5 1 19 SANITY_TESTED_DISTROS A list of the host distribution identifiers that the build system has been tested against Identifiers consist of the host distributor ID followe
57. anual html bitbake term Thus the generic term used here for the build system is the OpenEmbedded build system Development in the Yocto Project using Poky is closely tied to OpenEmbedded with changes always being merged to OE Core or BitBake first before being pulled back into Poky This practice benefits both projects immediately only have Python 2 4 or 2 5 but BitBake requires Python 2 6 or 2 7 Can still use the Yocto Project You can use a Stand alone tarball to provide Python 2 6 You can find pre built 32 and 64 bit versions of Python 2 6 at the following locations e 32 bit tarball http downloads yoctoproject org releases miscsupport python nativesdk standalone i686 tar bz2 e 64 bit tarball http downloads yoctoproject org releases miscsupport python nativesdk standalone x86 64 tar bz2 These tarballs are self contained with all required libraries and should work on most Linux Systems To use the tarballs extract them into the root directory and run the appropriate command export PATH o0pt poky sysroots i586 pokysdk linux usr bin PATH export PATH opt poky sysroots x86_64 pokysdk linux usr bin PATH Once you run the command BitBake uses Python 2 6 How can you claim Poky OpenEmbedded Core is stable There are three areas that help with stability The Yocto Project team keeps OE Core http www yoctoproject org docs 1 4 2 dev manual dev manual html oe core small and focused containing around 830
58. ar to the following in your local conf or distro configuration file export CCACHE DIR Note A side effect of the previous steps is that BitBake records the variable as a dependency of the build process in things like the shared state checksums If doing so results in unnecessary rebuilds of tasks you can whitelist the variable so that the shared state code ignores the dependency when it creates checksums For information on this process see the BB HASHBASE WHITELIST example in the Checksums Signatures section 6 6 BitBake Command Line Following is the BitBake help output bitbake help Usage bitbake options package Executes the specified task default is build for a given set of BitBake files It expects that BBFILES is defined which is a space separated list of files to be executed BBFILES does support wildcards Default BBFILES are the bb files in the current directory Options version show program s version number and exit h help show this help message and exit b BUILDFILE buildfile BUILDFILE execute the task against this bb file rather than a package from BBFILES Does not handle any dependencies k continue continue as much as possible after an error While the target that failed and those that depend on it cannot be remade the other dependencies of these targets can be processed all the same a tryaltconfigs continue with builds by trying to use alternative providers wh
59. are set Thus when MACHINE is set to qemux86 there exists the corresponding qemux86 conf machine configuration file which can be found in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory in meta conf machine The list of machines supported by the Yocto Project as shipped include the following MACHINE gemuarm MACHINE qemumips MACHINE gemuppc MACHINE gemux86 MACHINE qemux86 64 MACHINE atom pc MACHINE beagleboard MACHINE mpc8315e rdb MACHINE routerstationpro The last four are Yocto Project reference hardware boards which are provided in the meta yocto bsp layer Note Adding additional Board Support Package BSP layers to your configuration adds new possible settings for MACHINE MACHINE_ESSENTIAL_EXTRA_RDEPENDS A list of required machine specific packages to install as part of the image being built The build process depends on these packages being present Furthermore because this is a machine essential variable the list of packages are essential for the machine to boot The impact of this variable affects images based on packagegroup core boot including the core image minimal image This variable is similar to the MACHINE ESSENTIAL EXTRA RRECOMMENDS variable with the exception that the image being built has a build dependency on the variable s list of packages In other words the image will not build if a file i
60. as part of the variable The package name you attach to the RDEPENDS variable must appear as it would in the PACKAGES namespace before any renaming of the output package by classes like debian bbclass In many cases you do not need to explicitly add run time dependencies using RDEPENDS since some automatic handling occurs RM_WORK_EXCLUDE RPROVIDES RRECOMMENDS RREPLACES e shlibdeps If a run time package contains a shared library so the build processes the library in order to determine other libraries to which it is dynamically linked The build process adds these libraries to RDEPENDS when creating the run time package pcdeps If the package ships a pkg config information file the build process uses this file to add items to the RDEPENDS variable to create the run time packages With rm_work enabled this variable specifies a list of recipes whose work directories should not be removed See the Removing Work Files During the Build rm_work bbclass section for more details A list of package name aliases that a package also provides These aliases are useful for satisfying runtime dependencies of other packages both during the build and on the target as specified by RDEPENDS Note A package s own name is implicitly already in its RPROVIDES list As with all package controlling variables you must always use the variable in conjunction with a package name override Here is an example RPROVIDES PN
61. ation options and user configuration options in local conf which is found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory 3 2 Shared State Cache By design the OpenEmbedded build system builds everything from scratch unless BitBake can determine that parts do not need to be rebuilt Fundamentally building from scratch is attractive as it means all parts are built fresh and there is no possibility of stale data causing problems When developers hit problems they typically default back to building from scratch so they know the state of things from the start Building an image from scratch is both an advantage and a disadvantage to the process As mentioned in the previous paragraph building from scratch ensures that everything is current and starts from a known state However building from scratch also takes much longer as it generally means rebuilding things that do not necessarily need rebuilt The Yocto Project implements shared state code that supports incremental builds The implementation of the shared state code answers the following questions that were fundamental roadblocks within the OpenEmbedded incremental build support system What pieces of the system have changed and what pieces have not changed How are changed pieces of software removed and replaced How are pre built components that do not need to be rebuilt from scratch used when they are available For
62. aults to O fno omit frame pointer g Specifies a weak bias for recipe selection priority The most common usage of this is variable is to set it to 1 within a recipe for a development version of a piece of software Using the variable in this way causes the stable version of the recipe to build by default in the absence of PREFERRED VERSION being used to build the development version DEPENDS DESCRIPTION DESTDIR DISTRO DISTRO_EXTRA_RDEPENDS Note The bias provided by DEFAULT PREFERENCE is weak and is overridden by BBFILE PRIORITY if the that variable is different between two layers that contain different versions of the same recipe Lists a recipe s build time dependencies i e other recipe files The system ensures that all the dependencies listed have been built and have their contents in the appropriate sysroots before the recipe s configure task is executed The package description used by package managers If not set DESCRIPTION takes the value of the SUMMARY variable the destination directory The short name of the distribution This variable corresponds to a file with the extension conf located in a conf distro directory within the Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata that contains the distribution configuration The value must not contain spaces and is typically all lower case If the variable is blank a set of default configuration will be used
63. b folder For example the files for this manual reside in ref manual 5 1 4 meta This directory contains the OpenEmbedded Core metadata The directory holds recipes common classes and machine configuration for emulated targets qemux86 qemuarm and so forth 5 1 5 meta yocto This directory contains the configuration for the Poky reference distribution 5 1 6 meta yocto bsp This directory contains the Yocto Project reference hardware Board Support Packages BSPs For more information on BSPs see the Yocto Project Board Support Package BSP Developer s Guide http www yoctoproject org docs 1 4 2 bsp guide bsp guide html 5 1 7 meta hob This directory contains template recipes used by Hob which is a Yocto Project build user interface For more information on the Hob see the Hob Project http www yoctoproject org tools resources projects hob webpage 5 1 8 meta skeleton This directory contains template recipes for BSP and kernel development 5 1 9 scripts This directory contains various integration scripts that implement extra functionality in the Yocto Project environment e g QEMU scripts The oe init build env script appends this directory to the shell s PATH environment variable The scripts directory has useful scripts that assist contributing back to the Yocto Project such as create pull request and send pull request 5 1 10 oe init build env This script sets up the OpenEmbedded build env
64. b5c37fe6e24eec194bb29d22fdd55d73bcc709bf SRCREV emgd pn linux yocto caea08c988e0f41103bbel18eafca20348f95da02 SRCREV meta pn linux yocto c2ed0f16fdec628242a682897d5d86df4547cf24 core2 poky linux SRCREV pn kmod 62081c0f68905b22f375156d4532fd37fa5c8d33 SRCREV pn blktrace d6918c8832793b4205ed3bfede78c2f915c23385 SRCREV pn opkg 649 Note Here are some notes on using the buildhistory collect srcrevs command By default only values where the SRCREV was not hardcoded usually when AUTOREV was used are reported Use the a option to see all SRCREV values The output statements might not have any effect if overrides are applied elsewhere in the build system configuration Use the f option to add the forcevariable override to each output line if you need to work around this restriction The script does apply special handling when building for multiple machines However the script does place a comment before each set of values that specifies which triplet to which they belong as shown above e g emenlow poky linux 2 4 2 2 Build History Image Information The files produced for each image are as follows build id Human readable information about the build configuration and metadata source revisions dot Dependency graphs for the image that are compatible with graphviz files in image txt A list of files in the image with permissions owner group size and symlink information image info txt A
65. before a package is removed and started when the package is installed Three variables control this class INITSCRIPT PACKAGES INITSCRIPT NAME and INITSCRIPT PARAMS See the variable links for details 7 5 Binary Configuration Scripts binconfig bbclass Before pkg config had become widespread libraries shipped shell scripts to give information about the libraries and include paths needed to build software usually named LIBNAME config This class assists any recipe using such scripts During staging BitBake installs such scripts into the sysroots directory BitBake also changes all paths to point into the sysroots directory so all builds that use the script will use the correct directories for the cross compiling layout 7 6 Debian Renaming debian bbclass This class renames packages so that they follow the Debian naming policy i e eglibc becomes libc6 and eglibc devel becomes libc6 dev 7 7 Pkg config pkgconfig bbclass pkg config provides a standard way to get header and library information This class aims to smooth integration of pkg config into libraries that use it During staging BitBake installs pkg config data into the sysroots directory By making use of sysroot functionality within pkg config this class no longer has to manipulate the files 7 8 Archiving Sources archive bbclass Many software licenses require that source code and other materials be released with the binaries To help with that task t
66. box e busybox i a latest ll busybox dbg 4 ii latest ll busybox dev 4 latest wil busybox doc a latest Y At the top level there is a metadata revs file that lists the revisions of the repositories for the layers enabled when the build was produced The rest of the data splits into separate packages images and sdk directories the contents of which are described below 2 4 2 1 Build History Package Information The history for each package contains a text file that has name value pairs with information about the package For example buildhistory packages core2 poky linux busybox busybox latest contains the following PV 1 19 3 PR r3 RDEPENDS update rc d eglibc gt 2 13 RRECOMMENDS busybox syslog busybox udhcpc PKGSIZE 564701 FILES usr bin usr sbin usr libexec usr lib lib so etc com var bin sbin lib so usr share busybox usr lib busybox usr share pixmaps usr share applications usr share idl usr share omf usr share sounds usr lib bonobo servers FILELIST etc busybox links etc init d hwclock sh bin busybox bin sh Most of these name value pairs correspond to variables used to produce the package The exceptions are FILELIST which is the actual list of files in the package and PKGSIZE which is the total size of files in the package in bytes There is also a file corresponding to the recipe from which the package came e g buildhisto
67. c 2 13 r20 svnr15508 and bash 4 2 r1 This variable is comprised of the following PN EXTENDPE PV PR PN This variable can have two separate functions depending on the context a recipe name or a resulting package name PN refers to a recipe name in the context of a file used by the OpenEmbedded build system as input to create a package The name is normally extracted from the recipe file name For example if the recipe is named expat_2 0 1 bb then the default value of PN will be expat The variable refers to a package name in the context of a file created or produced by the OpenEmbedded build system If applicable the PN variable also contains any special suffix or prefix For example using bash to build packages for the native machine PN is bash native Using bash to build packages for the target and for Multilib PN would be bash and lib64 bash respectively PR The revision of the recipe The default value for this variable is rO PREMIRRORS Specifies additional paths from which the OpenEmbedded build system gets source code When the build system searches for source code it first tries the local download directory If that location fails the build system tries locations defined by PREMIRRORS the upstream source and then locations specified by MIRRORS in that order Assuming your distribution DISTRO is poky the default value for PREMIRRORS is defined in the conf distro poky conf file in the meta yocto
68. can accomplish this by using a line like the following PACKAGE ARCHS vardeps MACHINE This example explicitly adds the MACHINE variable as a dependency for PACKAGE ARCHS Consider a case with in line Python for example where BitBake is not able to figure out dependencies When running in debug mode i e using DDD BitBake produces output when it discovers something for which it cannot figure out dependencies The Yocto Project team has currently not managed to cover those dependencies in detail and is aware of the need to fix this situation Thus far this section has limited discussion to the direct inputs into a task Information based on direct inputs is referred to as the basehash in the code However there is still the question of a task s indirect inputs the things that were already built and present in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory The checksum or signature for a particular task needs to add the hashes of all the tasks on which the particular task depends Choosing which dependencies to add is a policy decision However the effect is to generate a master checksum that combines the basehash and the hashes of the task s dependencies At the code level there are a variety of ways both the basehash and the dependent task hashes can be influenced Within the BitBake configuration file we can give BitBake some extra information to help it construct the
69. ces them as soon as they are released What does the OpenEmbedded build system produce as output Because you can use the same set of recipes to create output of various formats the output of an OpenEmbedded build depends on how you start it Usually the output is a flashable image ready for the target device How do add my package to the Yocto Project To add a package you need to create a BitBake recipe For information on how to add a package see the section Writing a Recipe to Add a Package to Your Image http www yoctoproject org docs 1 4 2 dev manual dev manual html usingpoky extend addpkg in the Yocto Project Development Manual Do have to reflash my entire board with a new Yocto Project image when recompiling a package The OpenEmbedded build system can build packages in various formats such as IPK for OPKG Debian package deb or RPM You can then upgrade the packages using the package tools on the device much like on a desktop distribution such as Ubuntu or Fedora However package management on the target is entirely optional What is GNOME Mobile and what is the difference between GNOME Mobile and GNOME GNOME Mobile is a subset of the GNOME http www gnome org platform targeted at mobile and embedded devices The the main difference between GNOME Mobile and standard GNOME is that desktop orientated libraries have been removed along with deprecated libraries creating a much smaller footprint 12 101 s
70. cipes kernel linux defines the variables as follows LINUX_VERSION 3 4 24 The LINUX VERSION variable is used to define PV for the recipe PV LINUX_VERSION git SRCPV LINUX VERSION EXTENSION A string extension compiled into the version string of the Linux kernel built with the OpenEmbedded build system You define this variable in the kernel recipe For example the linux yocto kernel recipes all define the variable as follows LINUX VERSION EXTENSION yocto LINUX KERNEL TYPE Defining this variable essentially sets the Linux kernel configuration item CONFIG LOCALVERSION which is visible through the uname command Here is an example that shows the extension assuming it was set as previously shown uname r 3 7 0 rc8 custom LOG DIR Specifies the directory to which the OpenEmbedded build system writes overall log files The default directory is TMPDIR log For the directory containing logs specific to each task see the T variable M MACHINE Specifies the target device for which the image is built You define MACHINE in the local conf file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory By default MACHINE is set to qemux86 which is an x86 based architecture machine to be emulated using QEMU MACHINE qemux86 The variable corresponds to a machine configuration file of the same name through which machine specific configurations
71. cipes rt This directory contains package and image recipes for using and testing the PREEMPT RT kernel 5 3 19 meta recipes sato This directory contains the Sato demo reference UI UX and its associated applications and configuration data 5 3 20 meta recipes support This directory contains recipes used by other recipes but that are not directly included in images i e dependencies of other recipes 5 3 21 meta site This directory contains a list of cached results for various architectures Because certain autoconf test results cannot be determined when cross compiling due to the tests not able to run on a live system the information in this directory is passed to autoconf for the various architectures 5 3 22 meta recipes txt This file is a description of the contents of recipes Chapter 6 BitBake BitBake is a program written in Python that interprets the Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata used by the OpenEmbedded build system At some point developers wonder what actually happens when you enter bitbake core image sato This chapter provides an overview of what happens behind the scenes from BitBake s perspective Note BitBake strives to be a generic task executor that is capable of handling complex dependency relationships As such it has no real knowledge of what the tasks being executed actually do BitBake just considers a list of tasks with de
72. components is only supported for minimal and base images Furthermore if you are going to build an image using non GPLv3 components you must make the following changes in the local conf file before using the BitBake command to build the minimal or base image 1 Comment out the EXTRA_IMAGE FEATURES line 2 Set INCOMPATIBLE LICENSE GPLv3 From within the poky Git repository use the following command to list the supported images ls meta recipes images bb These recipes reside in the meta recipes core images meta recipes extended images meta recipes graphics images meta recipes qt images meta recipes rt images meta recipes sato images and meta skeleton recipes multilib images directories within the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory Although the recipe names are somewhat explanatory here is a list that describes them build appliance image An example virtual machine that contains all the pieces required to run builds using the build system as well as the build system itself You can boot and run the image using either the VMware Player http www vmware com products player overview html or VMware Workstation http www vmware com products workstation overview html For more information on this image see the Build Appliance http www yoctoproject org documentation build appliance page on the Yocto Project website core image base A console only ima
73. cover different parts of the source code The final example is from sysstat which presents a single license Path to additional licenses used during the build By default the OpenEmbedded build system uses COMMON_LICENSE DIR to define the directory that holds common license text used during the build The LICENSE PATH variable allows you to extend that location to other areas that have additional licenses LICENSE PATH path to additional common licenses LINUX_KERNEL_TYPE Defines the kernel type to be used in assembling the configuration The linux yocto recipes define standard tiny and preempt rt kernel types See the Kernel Types http www yoctoproject org docs 1 4 2 kernel dev kernel dev html kernel types section in the Yocto Project Linux Kernel Development Manual for more information on kernel types If you do not specify a LINUX KERNEL TYPE it defaults to standard Together with KMACHINE the LINUX KERNEL TYPE variable defines the search arguments used by the kernel tools to find the appropriate description within the kernel Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata with which to build out the sources and configuration LINUX_VERSION The Linux version from kernel org on which the Linux kernel image being built using the OpenEmbedded build system is based You define this variable in the kernel recipe For example the linux yocto 3 4 bb kernel recipe found in meta re
74. d standard crownbay The KBRANCH statements identify the kernel branch to use when building for the Crown Bay BSP In this case there are two identical statements one for each type of Crown Bay machine KBRANCH DEFAULT Defines the Linux kernel source repository s default branch used to build the Linux kernel The KBRANCH DEFAULT value is the default value for KBRANCH Unless you specify otherwise KBRANCH DEFAULT initializes to master KERNEL EXTRA ARGS Specifies additional make command line arguments the OpenEmbedded build system passes on when compiling the kernel KERNEL_FEATURES Includes additional metadata from the Yocto Project kernel Git repository In the OpenEmbedded build system the default Board Support Packages BSPs Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata is provided through the KMACHINE and KBRANCH variables You can use the KERNEL_FEATURES variable to further add metadata for all BSPs The metadata you add through this variable includes config fragments and features descriptions which usually includes patches as well as config fragments You typically override the KERNEL FEATURES variable for a specific machine In this way you can provide validated but optional sets of kernel configurations and features KERNEL_IMAGETYPE KERNEL_PATH KERNEL_SRC KFEATURE_DESCRIPTION KMACHINE For example the following adds netfilter to all the Yocto Project kernels and
75. d FILES variables The files listed within CONFFILES must be a subset of the files listed within FILES Because the configuration files you provide with CONFFILES are simply being identified so that the PMS will not overwrite them it makes sense that the files must already be included as part of the package through the FILES variable Note When specifying paths as part of the CONFFILES variable it is good practice to use appropriate path variables For example sysconfdir rather than etc or bindir rather than usr bin You can find a list of these variables at the top of the meta conf bitbake conf file in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory A list of files that contains autoconf test results relevant to the current build This variable is used by the Autotools utilities when running configure Specifies the list of packages to be added to the image You should only set this variable in the Local conf configuration file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory This variable replaces POKY EXTRA_INSTALL which is no longer supported The destination directory Specifies to build packages with debugging information This influences the value of the SELECTED OPTIMIZATION variable The options to pass in TARGET_CFLAGS and CFLAGS when compiling a system for debugging This variable def
76. d by the release as reported by the lsb_release tool or as read from etc 1lsb release Separate the list items with explicit newline characters n If SANITY TESTED DISTROS is not empty and the current value of NATIVELSBSTRING does not appear in the list then the build system reports a warning that indicates the current host distribution has not been tested as a build host SDKIMAGE_FEATURES Equivalent to IMAGE_FEATURES However this variable applies to the SDK generated from an image using the following command bitbake c populate sdk imagename SECTION The section in which packages should be categorized Package management utilities can make use of this variable SELECTED_OPTIMIZATION The variable takes the value of FULL_OPTIMIZATION unless DEBUG BUILD 1 In this case the value of DEBUG OPTIMIZATION is used SERIAL_CONSOLE The speed and device for the serial port used to attach the serial console This variable is given to the kernel as the console parameter and after booting occurs getty is started on that port so remote login is possible SIGGEN_EXCLUDERECIPES_ABISAHEt of recipes that are completely stable and will never change The ABI for the recipes in the list are presented by output from the tasks run to build the recipe Use of this variable is one way to remove dependencies from one recipe on another that affect task signatures and thus force rebuilds when the recipe changes Caution If you add an inappropriat
77. d the following files to your layer meta MACHINE recipes bsp netbase netbase MACHINE interfaces meta MACHINE recipes bsp netbase netbase 5 0 bbappend 12 20How do create images with more free space By default the OpenEmbedded build system creates images that are 1 3 times the size of the populated root filesystem To affect the image size you need to set various configurations Image Size The OpenEmbedded build system uses the IMAGE ROOTFS SIZE variable to define the size of the image in Kbytes The build system determines the size by taking into account the initial root filesystem size before any modifications such as requested size for the image and any requested additional free disk space to be added to the image Overhead Use the IMAGE OVERHEAD FACTOR variable to define the multiplier that the build system applies to the initial image size which is 1 3 by default Additional Free Space Use the IMAGE ROOTFS EXTRA SPACE variable to add additional free space to the image The build system adds this space to the image after it determines its IMAGE ROOTFS SIZE 12 21Why don t you support directories with spaces in the pathnames The Yocto Project team has tried to do this before but too many of the tools the OpenEmbedded build system depends on such as autoconf break when they find spaces in pathnames Until that situation changes the team will not support spaces in pathnames 12 22 How do use an external toolchain
78. d use the following in the conf file for the machine MACHINE_EXTRA_RRECOMMENDS kernel module examplewifi MACHINE_FEATURES Specifies the list of hardware features the MACHINE supports For example including the bluetooth feature causes the bluez bluetooth daemon to be built and added to the image It also causes the connman recipe to look at MACHINE_FEATURES and when it finds bluetooth there it enables the bluetooth support in ConnMan For a list of features supported by the Yocto Project as shipped see the Machine section MACHINE FEATURES BACKFILL Features to be added to MACHINE FEATURES if not also present in MACHINE FEATURES BACKFILL CONSIDERED This variable is set in the meta conf bitbake conf file It is not intended to be user configurable It is best to just reference the variable to see which machine features are being backfilled for all machine configurations See the Feature backfilling section for more information MACHINE FEATURES BACKFILL amp mNIGrB amp RiEBm MACHINE FEATURES BACKFILL that should not be backfilled i e added to MACHINE FEATURES during the build See the Feature backfilling section for more information MACHINEOVERRIDES Lists overrides specific to the current machine By default this list includes the value of MACHINE You can extend the list to apply variable overrides for classes of machines For example all QEMU emulated machines e g qamuarm qemux86 and so forth include a co
79. depends dot package depends dot and task depends dot files in the current directory These files show the package and task dependencies and are useful for debugging problems You can use the bitbake g u depexp targetname command to display the results in a more human readable form 2 3 4 General BitBake Problems You can see debug output from BitBake by using the D option The debug output gives more information about what BitBake is doing and the reason behind it Each D option you use increases the logging level The most common usage is DDD The output from bitbake DDD v targetname can reveal why BitBake chose a certain version of a package or why BitBake picked a certain provider This command could also help you in a situation where you think BitBake did something unexpected 2 3 5 Development Host System Issues Sometimes issues on the host development system can cause your build to fail Following are known host specific problems Be sure to always consult the Release Notes http www yoctoproject org download yocto project 142 poky 902 for a look at all release related issues eglibc initial fails to build If your development host system has the unpatched GNU Make 3 82 the do_install task fails for eglibc initial during the build Typically every distribution that ships GNU Make 3 82 as the default already has the patched version However some distributions such as Debian have GNU Make 3 82 as an option which is un
80. dule you want it to be installed But when the driver is built into the kernel you still want the build to succeed This variable sets up a recommends relationship so that in the latter case the build will not fail due to the missing package To accomplish this assuming the package for the module was called kernel module ab123 you would use the following in the machine s conf configuration file MACHINE ESSENTIAL EXTRA RRECOMMENDS kernel module ab123 Some examples of these machine essentials are flash screen keyboard mouse or touchscreen drivers depending on the machine MACHINE EXTRA RDEPENDS A list of machine specific packages to install as part of the image being built that are not essential for the machine to boot However the build process for more fully featured images depends on the packages being present This variable affects all images based on packagegroup base which does not include the core image minimal or core image basic images The variable is similar to the MACHINE EXTRA RRECOMMENDS variable with the exception that the image being built has a build dependency on the variable s list of packages In other words the image will not build if a file in this list is not found An example is a machine that has WiFi capability but is not essential for the machine to boot the image However if you are building a more fully featured image you want to enable the WiFi The package containing the firmware for t
81. e WORKDIR is defined slightly different TMPDIR work MACHINE poky TARGET 0S PN PV PR As an example again assume a Source Directory top level folder named poky and a default Build Directory at poky build In this case the working directory the build system uses to build the acl recipe which is being built for a MIPS based device is the following poky build tmp work mips poky linux acl 2 2 51 r2 Chapter 11 Variable Context While you can use most variables in almost any context such as conf bbclass inc and bb files some variables are often associated with a particular locality or context This chapter describes some common associations 11 1 Configuration The following subsections provide lists of variables whose context is configuration distribution machine and local 11 1 1 Distribution Distro This section lists variables whose configuration context is the distribution or distro DISTRO DISTRO_NAME e DISTRO VERSION MAINTAINER PACKAGE CLASSES e TARGET 0S TARGET FPU e TCMODE TCLIBC 11 1 2 Machine This section lists variables whose configuration context is the machine TARGET ARCH SERIAL CONSOLE PACKAGE EXTRA ARCHS IMAGE FSTYPES MACHINE FEATURES MACHINE EXTRA RDEPENDS MACHINE EXTRA RRECOMMENDS MACHINE ESSENTIAL EXTRA RDEPENDS MACHINE ESSENTIAL EXTRA RRECOMMENDS 11 1 3 Local This section lists variables whose configuration context is the
82. e symlinks are only useful for development purposes Thus the dev package is the correct location for them Some very rare cases do exist for dynamically loaded modules where these symlinks are needed instead in the main package debug files Checks for debug directories in anything but the dbg package The debug files should all be in the dbg package Thus anything packaged elsewhere is incorrect packaging arch Checks the Executable and Linkable Format ELF type bit size and endianness of any binaries to ensure they match the target architecture This test fails if any binaries don t match the type since there would be an incompatibility Sometimes software like bootloaders might need to bypass this check debug deps Checks that dbg packages only depend on other dbg packages and not on any other types of packages which would cause a packaging bug dev deps Checks that dev packages only depend on other dev packages and not on any other types of packages which would be a packaging bug pkgconfig Checks pc files for any TMPDIR WORKDIR paths Any pc file containing these paths is incorrect since pkg config itself adds the correct sysroot prefix when the files are accessed textrel Checks for ELF binaries that contain relocations in their text sections which can result in a performance impact at runtime pkgvarcheck Checks through the variables RDEPENDS RRECOMMENDS RSUGGESTS RCONFLICTS RPROVIDES RREPLACES FILES
83. e variable to this list the software might break at runtime if the interface of the recipe was changed after the other had been built SIGGEN_EXCLUDE_SAFE_RECIPEADERSOf recipe dependencies that should not be used to determine SITEINFO_ENDIANNESS SITEINFO_BITS SOC FAMILY SPECIAL PKGSUFFIX SRC URI signatures of tasks from one recipe when they depend on tasks from another recipe For example SIGGEN EXCLUDE SAFE RECIPE DEPS intone gt mplayer2 In this example intone depends on mplayer2 Use of this variable is one mechanism to remove dependencies that affect task signatures and thus force rebuilds when a recipe changes Caution If you add an inappropriate dependency for a recipe relationship the software might break during runtime if the interface of the second recipe was changed after the first recipe had been built Specifies the endian byte order of the target system The value should be either le for little endian or be for big endian Specifies the number of bits for the target system CPU The value should be either 32 or 64 Groups together machines based upon the same family of SOC System On Chip You typically set this variable in a common inc file that you include in the configuration files of all the machines Note You must include conf machine include soc family inc for this variable to appear in MACHINEOVERRIDES A list of prefixes for PN used by the OpenEmbedded build system to creat
84. e variants of recipes or packages The list specifies the prefixes to strip off during certain circumstances such as the generation of the BPN variable The list of source files local or remote This variable tells the OpenEmbedded build system which bits to pull in for the build and how to pull them in For example if the recipe or append file only needs to fetch a tarball from the Internet the recipe or append file uses a single SRC URI entry On the other hand if the recipe or append file needs to fetch a tarball apply two patches and include a custom file the recipe or append file would include four instances of the variable The following list explains the available URI protocols file Fetches files which are usually files shipped with the Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual htmlz metadata from the local machine The path is relative to the FILESPATH variable Thus the build system searches in order from the following directories which are assumed to be a subdirectories of the directory in which the recipe file bb or append file bbappend resides BPN The base recipe name without any special suffix or version numbers BP BPN PV The base recipe name and version but without any special package name suffix files Files within a directory which is named files and is also alongside the recipe or append file Note If you want the build system t
85. ecipes PACKAGES DYNAMIC does not actually satisfy the dependencies it only states that they should be satisfied For example if a hard runtime dependency RDEPENDS of another package is satisfied at build time through the PACKAGES DYNAMIC variable but a package with the module name is never actually produced then the other package will be broken Thus if you attempt to include that package in an image you will get a dependency failure from the packaging system during do_rootfs Typically if there is a chance that such a situation can occur and the package that is not created is valid without the dependency being satisfied then you should use RRECOMMENDS a soft runtime dependency instead of RDEPENDS For an example of how to use the PACKAGES DYNAMIC variable when you are splitting packages see the Handling Optional Module Packaging http www yoctoproject org docs 1 4 2 dev manual dev manual html handling optional module packaging section in the Yocto Project Development Manual PARALLEL_MAKE Specifies extra options that are passed to the make command during the compile tasks This variable is usually in the form j 4 where the number represents the maximum number of parallel threads make can run If you development host supports multiple cores a good rule of thumb is to set this variable to twice the number of cores on the host PF Specifies the recipe or package name and includes all version and revision numbers i e eglib
86. ecipes based on licensing For example you can broaden the matching capabilities by using license flags string subsets in the whitelist Note When using a string subset be sure to use the part of the expanded string that precedes the appended underscore character e g usethispart_1 3 usethispart_1 4 and so forth For example simply specifying the string commercial in the whitelist matches any expanded LICENSE FLAGS definition that starts with the string commercial such as commercial_foo and commercial_bar which are the strings the build system automatically generates for hypothetical recipes named foo and bar assuming those recipes simply specify the following LICENSE FLAGS commercial Thus you can choose to exhaustively enumerate each license flag in the whitelist and allow only specific recipes into the image or you can use a string subset that causes a broader range of matches to allow a range of recipes into the image This scheme works even if the LICENSE FLAG string already has PN appended For example the build system turns the license flag commercial 1 2 foo into commercial 1 2 foo foo and would match both the general commercial and the specific commercial_1 2 foo strings found in the whitelist as expected Here are some other scenarios You can specify a versioned string in the recipe such as commercial_foo_1 2 in a foo recipe The build system expands this string to commercial_foo_1 2 foo
87. ee the error chmod XXXXX new permissions are r xrwxrwx not r xr xr x What is wrong You are probably running the build on an NTFS filesystem Use ext2 ext3 or ext4 instead 12 11How do make the Yocto Project work in RHEL CentOS To get the Yocto Project working under RHEL CentOS 5 1 you need to first install some required packages The standard CentOS packages needed are Development tools selected during installation texi2html compat gcc 34 On top of these you need the following external packages python sqlite2 from DAG repository http dag wieers com rpm packages python sqlite2 help2man from Karan repository http centos karan org el4 extras stable x86 64 RPMS repodata repoview help2man 0 1 33 1 2 html Once these packages are installed the OpenEmbedded build system will be able to build standard images However there might be a problem with the QEMU emulator segfaulting You can either disable the generation of binary locales by setting ENABLE BINARY LOCALE GENERATION to O or by removing the linux 2 6 execshield patch from the kernel and rebuilding it since that is the patch that causes the problems with QEMU Note For information on distributions that the Yocto Project uses during validation see the Distribution Support https wiki yoctoproject org wiki Distribution Support Wiki page For notes about using the Yocto Project on a RHEL 4 based host see the Building on RHEL4 https
88. eeded to build an image for a headless system sudo yum install gawk make wget tar bzip2 gzip python unzip perl patch diffutils diffstat git cpp gcc gcc c eglibc devel texinfo chrpath ccache Graphical Extras Packages recommended if the host system has graphics support sudo yum install SDL devel xterm Documentation Packages needed if you are going to build out the Yocto Project documentation manuals sudo yum install make docbook style dsssl docbook style xsl docbook dtds docbook utils fop libxslt ADT Installer Extras Packages needed if you are going to be using the Application Development Toolkit ADT Installer http www yoctoproject org docs 1 4 2 adt manual adt manual html using the adt installer sudo yum install autoconf automake libtool glib2 devel 1 3 2 3 OpenSUSE Packages The following list shows the required packages by function given a supported OpenSUSE Linux distribution Essentials Packages needed to build an image for a headless system sudo zypper install python gcc gcc c git chrpath make wget python xml diffstat texinfo python curses patch Graphical Extras Packages recommended if the host system has graphics support sudo zypper install libSDL devel xterm Documentation Packages needed if you are going to build out the Yocto Project documentation manuals sudo zypper install make fop xsltproc ADT Installer Extras Packages needed if you are going to be using t
89. egular expression that resolves to one or more target machines with which a recipe is compatible The regular expression is matched against MACHINEOVERRIDES You can use the variable to stop recipes from being built for machines with which the recipes are not compatible Stopping these builds is particularly useful with kernels The variable also helps to increase parsing speed since the build system skips parsing recipes not compatible with the current machine CONFFILES CONFIG_SITE CORE_IMAGE_EXTRA_INSTALL D D DEBUG BUILD DEBUG_OPTIMIZATION DEFAULT_PREFERENCE Identifies editable or configurable files that are part of a package If the Package Management System PMS is being used to update packages on the target system it is possible that configuration files you have changed after the original installation and that you now want to remain unchanged are overwritten In other words editable files might exist in the package that you do not want reset as part of the package update process You can use the CONFFILES variable to list the files in the package that you wish to prevent the PMS from overwriting during this update process To use the CONFFILES variable provide a package name override that identifies the resulting package Then provide a space separated list of files Here is an example CONFFILES PN sysconfdir filel sysconfdir file2 sysconfdir file3 A relationship exists between the CONFFILES an
90. ehensive guide to the BitBake tool You can find the BitBake User Manual in the bitbake doc manual directory which is found in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory e QEMU http wiki qemu org Index html An open source machine emulator and virtualizer 13 6 Contributions The Yocto Project gladly accepts contributions You can submit changes to the project either by creating and sending pull requests or by submitting patches through email For information on how to do both as well as information on how to find out who is the maintainer for areas of code see the How to Submit a Change http www yoctoproject org docs 1 4 2 dev manual dev manual html how to submit a change section in the Yocto Project Development Manual
91. en it is enabled or disabled You can omit any argument you like but must retain the separating commas The arguments specify the following 1 Extra arguments that should be added to the configure script argument list EXTRA OECONF if the feature is enabled 2 Extra arguments that should be added to EXTRA OECONF if the feature is disabled 3 Additional build dependencies DEPENDS that should be added if the feature is enabled 4 Additional runtime dependencies RDEPENDS that should be added if the feature is enabled Consider the following example taken from the librsvg recipe In this example the feature is croco which has three arguments that determine the feature s behavior PACKAGECONFIG croco PACKAGECONFIG croco with croco without croco Libcroco The with croco and libcroco arguments apply only if the feature is enabled In this case with croco is added to the configure script argument list and Libcroco is added to DEPENDS On the other hand if the feature is disabled say through a bbappend file in another layer then the second argument without croco is added to the configure script rather than with croco PACKAGES The list of packages to be created from the recipe The default value is the following PN dbg PN staticdev PN dev PN doc PN locale PACK PACKAGES DYNAMIC A promise that your recipe satisfies runtime dependencies for optional modules that are found in other r
92. en removed 4 1 2 6 Removed Recipes The following recipes have been removed For most of them it is unlikely that you would have any references to them in your own Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata However you should check your metadata against this list to be sure e libx11 trim Replaced by libx11 which has a negligible size difference with modern Xorg xserver xorg lite Use xserver xorg which has a negligible size difference when DRI and GLX modules are not installed xserver kdrive Effectively unmaintained for many years mesa xlib No longer serves any purpose galago Replaced by telepathy gail Functionality was integrated into GTK 2 13 eggdbus No longer needed gcc intermediate The build has been restructured to avoid the need for this step libgsmd Unmaintained for many years Functionality now provided by ofono instead contacts dates tasks eds tools Largely unmaintained PIM application suite It has been moved to meta gnome in meta openembedded In addition to the previously listed changes the meta demoapps directory has also been removed because the recipes in it were not being maintained and many had become obsolete or broken Additionally these recipes were not parsed in the default configuration Many of these recipes are already provided in an updated and maintained form within the OpenEmbedded community layers such as meta oe and meta gno
93. en rnnt rennen nen nennen 5 2 Using the Yocto Project ais dd A btee begins oS RE Yu cae ie ane ce 6 2 1 RUNNING a B lld eros cene be thks check ne ES eco EE eee tke 6 21 1 Build OVerVvIgeW or A A aad baled Ras 6 2 1 2 Building an Image Using GPL Components sssssse mme 6 2 2 Installing and Using the Result 0 0 0 mme ene nennen rne 6 2 3 Debugging Build Failures i e ot re eset t eg ut ia EA dag Red el apta 7 2 3 1 Task Failures ai 2 2 A reet er te Fe A et ger Pee oe ce eae 7 2 3 2 Running Specific Tasks i ore d e REM Re Eo ER EE eee 7 2 3 3 Dependency Graplis oed erede ier a cach ER QE NER UE Euge 8 2 3 4 General BitBake Problems ssssssssssseseseneee emen mener nnne 8 2 3 5 Development Host System ISSUES sssssssssss meme mener nnn 8 2 3 6 Building with No Dependencies ssssssseee meer 8 2 3 Variables 4c muet ette dan rre dica de Mar ec dw Id 8 2 3 8 Recipe Logging Mechanisms ssssssss meme ener nenne 8 zac Ee dg DC Em 9 2 4 Maintaining Build Output Quality 2 0 menm meme nennen 9 2 4 1 Enabling and Disabling Build History ssssm mee 10 2 4 2 Understanding What the Build History Contains see 11 3 Technical Details sy ns 16 3 1 Yocto Project COMPONENTS mic neha ce oC ea ia eae io ca a eee eee 16 3cl 1 A TO 16 3 1 2 Metadata RECIPES 5 eo teen a ADR RARO CHEER LEER E
94. ere possible f force force run of specified cmd regardless of stamp status C CMD cmd CMD Specify task to execute Note that this only executes the specified task for the providee and the packages it depends on i e compile does not implicitly call stage for the dependencies IOW use only if you know what you are doing Depending on the base bbclass a listtasks tasks is defined and will show available tasks r PREFILE read PREFILE read the specified file before bitbake conf R POSTFILE postread POSTFILE read the specified file after bitbake conf V verbose output more chit chat to the terminal D debug Increase the debug level You can specify this more than once n dry run don t execute just go through the motions S dump signatures don t execute just dump out the signature construction information p parse only quit after parsing the BB files developers only S show versions show current and preferred versions of all packages e environment show the global or per package environment this is what used to be bbread g graphviz emit the dependency trees of the specified packages in the dot syntax I EXTRA_ASSUME PROVIDED ignore deps EXTRA ASSUME PROVIDED Assume these dependencies don t exist and are already provided equivalent to ASSUME PROVIDED Useful to make dependency graphs more appealing l DEBUG DOMAINS log domains DEBUG DOMAINS Show debug logging for the specif
95. ers a build failure and notifies the developer Notification allows the developer to review and address the license text changes Also note that if a mismatch occurs during the build the correct md5 checksum is placed in the build log and can be easily copied to the recipe There is no limit to how many files you can specify using the LIC FILES CHKSUM variable Generally however every project requires a few specifications for license tracking Many projects have a COPYING file that stores the license information for all the source code files This practice allows you to just track the COPYING file as long as it is kept up to date Tip If you specify an empty or invalid md5 parameter BitBake returns an md5 mis match error and displays the correct md5 parameter value during the build The correct parameter is also captured in the build log Tip If the whole file contains only license text you do not need to use the beginline and endline parameters 3 5 2 Enabling Commercially Licensed Recipes By default the OpenEmbedded build system disables components that have commercial or other special licensing requirements Such requirements are defined on a recipe by recipe basis through the LICENSE FLAGS variable definition in the affected recipe For instance the HOME poky meta recipes multimedia gstreamer gst plugins ugly recipe contains the following statement LICENSE_FLAGS commercial Here is a slightly more complicated
96. es might not be included if the distribution itself does not support them One method you can use to determine which recipes are checking to see if a particular feature is contained or not is to grep through the Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual htmlzZ metadata for the feature Here is an example that discovers the recipes whose build is potentially changed based on a given feature cd HOME poky git grep contains MACHINE FEATURES feature 9 1 Distro The items below are features you can use with DISTRO FEATURES Features do not have a one to one correspondence to packages and they can go beyond simply controlling the installation of a package or packages Sometimes a feature can influence how certain recipes are built For example a feature might determine whether a particular configure option is specified within do configure for a particular recipe This list only represents features as shipped with the Yocto Project metadata alsa Include ALSA support OSS compatibility kernel modules installed if available bluetooth Include bluetooth support integrated BT only cramfs Include CramFS support ext2 Include tools for supporting for devices with internal HDD Microdrive for storing files instead of Flash only devices ipsec Include IPSec support ipv6 Include IPv6 support irda Include Irda support keyboard Include keyboard support e g keymaps will be loaded duri
97. eston 2 Launch Weston in the shell weston 3 5 Licenses This section describes the mechanism by which the OpenEmbedded build system tracks changes to licensing text The section also describes how to enable commercially licensed recipes which by default are disabled For information that can help you maintain compliance with various open source licensing during the lifecycle of the product see the Maintaining Open Source License Compliance During Your Project s Lifecycle http www yoctoproject org docs 1 4 2 dev manual dev manual html maintaining open source license compliance during your products lifecycle section in the Yocto Project Development Manual 3 5 1 Tracking License Changes The license of an upstream project might change in the future In order to prevent these changes going unnoticed the LIC FILES CHKSUM variable tracks changes to the license text The checksums are validated at the end of the configure step and if the checksums do not match the build will fail 3 5 1 1 Specifying theLIC FILES CHKSUM Variable The LIC_FILES CHKSUM variable contains checksums of the license text in the source code for the recipe Following is an example of how to specify LIC FILES CHKSUM LIC FILES CHKSUM file COPYING md5 xxxx file licfilel txt beginline 5 endline 29 md5 yyyy file licfile2 txt endline 50 md5 zzzz The build system uses the S variable as the default directory used when searching files listed in
98. f installed packages ordered by size installed packages txt A list of installed packages with full package filenames Here is an example of sdk info txt DISTRO poky DISTRO VERSION 1 3 snapshot 20130327 SDK_NAME poky eglibc i686 arm SDK_VERSION 1 3 snapshot SDKMACHINE SDKIMAGE FEATURES BAD RECOMMENDATIONS SDKSIZE 352712 dev pkgs dbg pkgs Other than SDKSIZE which is the total size of the files in the SDK in Kbytes the name value pairs are variables that might have influenced the content of the SDK This information is often useful when you are trying to determine why a change in the package or file listings has occurred 2 4 2 5 Examining Build History Information You can examine build history output from the command line or from a web interface To see any changes that have occurred assuming you have BUILDHISTORY COMMIT 1 you can simply use any Git command that allows you to view the history of a repository Here is one method git log p You need to realize however that this method does show changes that are not significant e g a package s size changing by a few bytes A command line tool called buildhistory diff does exist though that queries the Git repository and prints just the differences that might be significant in human readable form Here is an example poky poky scripts buildhistory diff HEAD Changes to images qemux86 64 eglibc core image minimal files in image txt etc
99. figuration files some standard classes are included The base bbclass file is always included Other classes that are specified in the configuration using the INHERIT variable are also included Class files are searched for in a classes subdirectory under the paths in BBPATH in the same way as configuration files After classes are included the variable BBFILES is set usually in local conf and defines the list of places to search for bb files By default the BBFILES variable specifies the meta recipes directory within Poky Adding extra content to BBFILES is best achieved through the use of BitBake layers as described in the Understanding and Creating Layers http www yoctoproject org docs 1 4 2 dev manual dev manual html understanding and creating layers section of the Yocto Project Development Manual BitBake parses each bb file in BBFILES and stores the values of various variables In summary for each bb file the configuration plus the base class of variables are set followed by the data in the bb file itself followed by any inherit commands that bb file might contain Because parsing bb files is a time consuming process a cache is kept to speed up subsequent parsing This cache is invalid if the timestamp of the bb file itself changes or if the timestamps of any of the include configuration files or class files on which the bb file depends change 6 2 Preferences and Providers Once all the bb files have been
100. fined in the bblayers conf configuration file in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory Here is an example BBLAYERS home scottrif poky meta home scottrif poky meta yocto home scottrif poky meta yocto bsp home scottrif poky meta mykernel BBLAYERS_NON_REMOVABLE home scottrif poky meta home scottrif poky meta yocto This example enables four layers one of which is a custom user defined layer named meta mykernel Lists core layers that cannot be removed from the bblayers conf file In order for BitBake to build your image your bblayers conf file must include the meta and meta yocto core layers Here is an example that shows these two layers listed in the BBLAYERS_NON_REMOVABLE statement BP BPN BUILDDIR C CFLAGS COMBINED_FEATURES COMPATIBLE_HOST COMPATIBLE_MACHINE BBLAYERS home scottrif poky meta home scottrif poky meta yocto home scottrif poky meta yocto bsp home scottrif poky meta mykernel BBLAYERS NON REMOVABLE home scottrif poky meta home scottrif poky meta yocto The base recipe name and version but without any special recipe name suffix i e native lib64 and so forth BP is comprised of the following BPN PVj The bare name of the recipe This variable is a version of the PN variable but removes common suffixes such as native and cross as well as remove
101. formation about how that package was configured and built You can find more information on licensing in the Licensing http www yoctoproject org docs 1 4 2 dev manual dev manual html licensing and Maintaining Open Source License Compliance During Your Product s Lifecycle http www yoctoproject org docs 1 4 2 dev manual dev manual html maintaining open source license compliance during your products lifecycle sections both of which are in the Yocto Project Development Manual 12 18 How do disable the cursor on my touchscreen device You need to create a form factor file as described in the Miscellaneous Recipe Files http www yoctoproject org docs 1 4 2 bsp guide bsp guide html bsp filelayout misc recipes section in the Yocto Project Board Support Packages BSP Developer s Guide Set the HAVE_TOUCHSCREEN variable equal to one as follows HAVE TOUCHSCREEN 1 12 19 How do make sure connected network interfaces are brought up by default The default interfaces file provided by the netbase recipe does not automatically bring up network interfaces Therefore you will need to add a BSP specific netbase that includes an interfaces file See the Miscellaneous Recipe Files http www yoctoproject org docs 1 4 2 bsp guide bsp guide html bsp filelayout misc recipes section in the Yocto Project Board Support Packages BSP Developer s Guide for information on creating these types of miscellaneous recipe files For example ad
102. g runs any Makefile present installing empty by default and packaging empty by default These classes are often overridden or extended by other classes such as autotools bbclass or package bbclass The class also contains some commonly used functions such as oe runmake 7 2 Autotooled Packages autotools bbclass Autotools autoconf automake and libtool bring standardization This class defines a set of tasks configure compile etc that work for all Autotooled packages It should usually be enough to define a few standard variables and then simply inherit autotools This class can also work with software that emulates Autotools For more information see the Autotooled Package http www yoctoproject org docs 1 4 2 dev manual dev manual html usingpoky extend addpkg autotools section in the Yocto Project Development Manual It s useful to have some idea of how the tasks defined by this class work and what they do behind the scenes do configure Regenerates the configure script using autoreconf and then launches it with a standard set of arguments used during cross compilation You can pass additional parameters to configure through the EXTRA OECONF variable do compile Runs make with arguments that specify the compiler and linker You can pass additional arguments through the EXTRA OEMAKE variable do install Runs make install and passes a destination directory option which takes its value from the standard DES
103. g do taskname pid Looking at the expanded shell functions in the run file and the output in the log files is a useful debugging technique For Python tasks BitBake executes the task internally and logs information to the controlling terminal Future versions of BitBake will write the functions to files similar to the way shell tasks are handled Logging will be handled in a way similar to shell tasks as well Once all the tasks have been completed BitBake exits When running a task BitBake tightly controls the execution environment of the build tasks to make sure unwanted contamination from the build machine cannot influence the build Consequently if you do want something to get passed into the build task s environment you must take a few steps 1 Tell BitBake to load what you want from the environment into the data store You can do so through the BB_ENV_EXTRAWHITE variable For example assume you want to prevent the build system from accessing your HOME ccache directory The following command tells BitBake to load CCACHE DIR from the environment into the data store export BB ENV EXTRAWHITE BB ENV EXTRAWHITE CCACHE DIR 2 Tell BitBake to export what you have loaded into the environment store to the task environment of every running task Loading something from the environment into the data store previous step only makes it available in the datastore To export it to the task environment of every running task use a command simil
104. g the target core image multilib example An example image that includes a Lib32 version of Bash into an otherwise standard sato image The image assumes a lib32 multilib has been enabled in the your configuration Tip From the Yocto Project release 1 1 onwards live and directdisk images have been replaced by a live option in IMAGE FSTYPES that will work with any image to produce an image file that can be copied directly to a CD or USB device and run asis To build a live image simply add live to IMAGE FSTYPES within the local conf file or wherever appropriate and then build the desired image as normal Chapter 9 Reference Features This chapter provides a reference of shipped machine and distro features you can include as part of the image a reference on image types you can build and a reference on feature backfilling Features provide a mechanism for working out which packages should be included in the generated images Distributions can select which features they want to support through the DISTRO_ FEATURES variable which is set in the poky conf distribution configuration file Machine features are set in the MACHINE FEATURES variable which is set in the machine configuration file and specifies the hardware features for a given machine These two variables combine to work out which kernel modules utilities and other packages to include A given distribution can support a selected subset of features so some machine featur
105. ge that fully supports the target device hardware core image minimal A small image just capable of allowing a device to boot core image minimal dev A core image minimal image suitable for development work using the host The image includes headers and libraries you can use in a host development environment core image minimal initramfs A core image minimal image that has the Minimal RAM based Initial Root Filesystem initramfs as part of the kernel which allows the system to find the first init program more efficiently core image minimal mtdutils A core image minimal image that has support for the Minimal MTD Utilities which let the user interact with the MTD subsystem in the kernel to perform operations on flash devices core image basic A console only image with more full featured Linux system functionality installed core image 1sb An image that conforms to the Linux Standard Base LSB specification e core image 1sb dev A core image lsb image that is suitable for development work using the host The image includes headers and libraries you can use in a host development environment core image lsb sdk A core image lsb that includes everything in meta toolchain but also includes development headers and libraries to form a complete standalone SDK This image is suitable for development using the target core image clutter An image with support for the Open GL based toolkit Clutter which enables develop
106. guration information such as u boot and grub 5 3 8 meta recipes connectivity This directory contains libraries and applications related to communication with other devices 5 3 9 meta recipes core This directory contains what is needed to build a basic working Linux image including commonly used dependencies 5 3 10 meta recipes devtools This directory contains tools that are primarily used by the build system The tools however can also be used on targets 5 3 11 meta recipes extended This directory contains non essential applications that add features compared to the alternatives in core You might need this directory for full tool functionality or for Linux Standard Base LSB compliance 5 3 12 meta recipes gnome This directory contains all things related to the GTK application framework 5 3 13 meta recipes graphics This directory contains X and other graphically related system libraries 5 3 14 meta recipes kernel This directory contains the kernel and generic applications and libraries that have strong kernel dependencies 5 3 15 meta recipes lsb4 This directory contains recipes specifically added to support the Linux Standard Base LSB version 4 X 5 3 16 meta recipes multimedia This directory contains codecs and support utilities for audio images and video 5 3 17 meta recipes qt This directory contains all things related to the Qt application framework 5 3 18 meta re
107. h the FILES variable are editable and you know they should not be overwritten during the package update process by the Package Management System PMS you can identify these files so that the PMS will not overwrite them See the CONFFILES variable for information on how to identify these files to the PMS FILESEXTRAPATHS Extends the search path the OpenEmbedded build system uses when looking for files and patches as it processes recipes and append files The directories BitBake uses when it processes recipes are defined by the FILESPATH variable and can be extended using FILESEXTRAPATHS Best practices dictate that you accomplish this by using the variable from within a bbappend file and that you prepend paths as follows FILESEXTRAPATHS prepend THISDIR PN In the above example the build system looks for files in a directory that has the same name as the corresponding append file Note When extending FILESEXTRAPATHS be sure to use the immediate expansion operator Immediate expansion makes sure that BitBake evaluates THISDIR at the time the directive is encountered rather than at some later time when expansion might result in a directory that does not contain the files you need Also include the trailing separating colon character if you are prepending The trailing colon character is necessary because you are directing BitBake to extend the path by prepending directories to the search path Here is another commo
108. hardware sssnmme 34 5 2 The Build Directory build 000 mene emen een nennen nene nnne nnns 34 5 2 1 buxtd pseudodore rai i e hit EL ERA ROME TOUR eget RE EXER ERR Rx 35 5 2 2 build conf local CONF ossis ee eee deese eager eei Dee e eec duas 35 5 2 3 build conf bblayers conf rrenen p a a E nennen rne 35 5 24 build conf sanity 1nfO seed a a da alt 35 5 2 5 bur td d wnloadS eii aaie EEA aa Ti SEENE 35 5 2 6 build sstate cache muii a A cede A A 35 5 2 7 b ud ld tlp A ai EENE 35 5 2 8 build tmp buildstats sssssssssssseee eene hene nnne rene nnns 35 5 2 9 buixtd7 tmp cache io di reto ee sa ter ER PERRA CX ER RR CH ELA er ENA aAA DERE ER YS 35 5 2 10 build tmp deploy n cbr dote d oed eo dede e dg re EU Pak 35 5 2 11 build tmp deploy deb cc ede de ee eh eR RE Peine ds 36 5 2 12 build tmp deploy rpm ssssssssseeem m Hee nnne nennen rne 36 5 2 13 build tmp deploy licenses sss meme mene nennen 36 5 2 14 build tmp deploy images sss mmm ener nnns 36 5 2 15 build tmp deploy ipk irinin iea a aE aaea Ea nennen nnne KAREA 36 5 2 16 build tmp sysroots mrii ai aina a aE hene ai aa EEE ENa 36 52 17 buitd tmp stamps A E uten Ae IE EE LAKER lous ERE AERE 36 5 2 18 b iltd tmp VOG iO tee eee eA NE ede 37 52 19 bur ld tmp pkgdata x ected Ge a ly ERA ia 37 522 202 BULUO EMp WOFK nene dede onte dne hee es d an Penta A Rira ved ets 37
109. he Application Development Toolkit ADT Installer http www yoctoproject org docs 1 4 2 adt manual adt manual html using the adt installer sudo zypper install autoconf automake libtool glib2 devel 1 3 2 4 CentOS Packages The following list shows the required packages by function given a supported CentOS Linux distribution Essentials Packages needed to build an image for a headless system sudo yum y install gawk make wget tar bzip2 gzip python unzip perl patch diffutils diffstat git cpp gcc gcc c glibc devel texinfo chrpath Graphical Extras Packages recommended if the host system has graphics support sudo yum y install SDL devel xterm Documentation Packages needed if you are going to build out the Yocto Project documentation manuals sudo yum y install make docbook style dsssl docbook style xsl docbook dtds docbook utils fop libxslt ADT Installer Extras Packages needed if you are going to be using the Application Development Toolkit ADT Installer http www yoctoproject org docs 1 4 2 adt manual adt manual html using the adt installer sudo yum y install autoconf automake libtool glib2 devel Note Depending on the CentOS version you are using other requirements and dependencies might exist For details you should look at the CentOS sections on the Poky GettingStarted Dependencies https wiki yoctoproject org wiki Poky GettingStarted Dependencies wiki page 1 4 Obtaining the
110. he WiFi hardware is always expected to exist so it is acceptable for the build process to depend upon finding the package In this case assuming the package for the firmware was called wifidriver firmware you would use the following in the conf file for the machine MACHINE EXTRA RDEPENDS wifidriver firmware MACHINE EXTRA RRECOMMENDS A list of machine specific packages to install as part of the image being built that are not essential for booting the machine The image being built has no build dependency on this list of packages This variable affects only images based on packagegroup base which does not include the core image minimal or core image basic images This variable is similar to the MACHINE_EXTRA_RDEPENDS variable with the exception that the image being built does not have a build dependency on the variable s list of packages In other words the image will build if a file in this list is not found An example is a machine that has WiFi capability but is not essential For the machine to boot the image However if you are building a more fully featured image you want to enable WiFi In this case the package containing the WiFi kernel module will not be produced if the WiFi driver is built into the kernel in which case you still want the build to succeed instead of failing as a result of the package not being found To accomplish this assuming the package for the module was called kernel module examplewifi you woul
111. he Yocto Project Linux Kernel Development Manual http www yoctoproject org docs 1 4 2 kernel dev kernel dev html For Board Support Package BSP structure information see the Yocto Project Board Support Package BSP Developer s Guide http www yoctoproject org docs 1 4 2 bsp guide bsp guide html You can also find lots of Yocto Project information on the Yocto Project website http www yoctoproject org 1 2 Documentation Overview This reference manual consists of the following Using the Yocto Project Provides an overview of the components that make up the Yocto Project followed by information about debugging images created in the Yocto Project Technical Details Describes fundamental Yocto Project components as well as an explanation behind how the Yocto Project uses shared state sstate cache to speed build time Directory Structure Describes the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory created either by unpacking a released Yocto Project tarball on your host development system or by cloning the upstream Poky http www yoctoproject org docs 1 4 2 dev manual dev manual html poky Git repository BitBake Provides an overview of the BitBake tool and its role within the Yocto Project Classes Describes the classes used in the Yocto Project Images Describes the standard images that the Yocto Project supports Features Describes mechanisms for creating dist
112. he following classes are provided archive original sources bbclass archive patched sources bbclass archive configured sources bbclass archiver bbclass For more details on the source archiver see the Maintaining Open Source License Compliance During Your Product s Lifecycle http www yoctoproject org docs 1 4 2 dev manual dev manual html maintaining open source license compliance during your products lifecycle section in the Yocto Project Development Manual 7 9 Perl Modules cpan bbclass Recipes for Perl modules are simple These recipes usually only need to point to the source s archive and then inherit the proper bbclass file Building is split into two methods depending on which method the module authors used Modules that use old Makefile PL based build system require cpan bbclass in their recipes e Modules that use Build PL based build system require using cpan_build bbclass in their recipes 7 10 Python Extensions distutils bbclass Recipes for Python extensions are simple These recipes usually only need to point to the source s archive and then inherit the proper bbclass file Building is split into two methods depending on which method the module authors used Extensions that use an Autotools based build system require Autotools and distutils based bbclasse files in their recipes Extensions that use distutils based build systems require distutils bbclass in their recipes 7 11 Developer She
113. he kernel branch that is validated patched and configured during a build The KBRANCH variable is optional You can use it to trigger checks to ensure the exact kernel branch you want is being used by the build process Values for this variable are set in the kernel s recipe file and the kernel s append file For example if you are using the Yocto Project kernel that is based on the Linux 3 4 kernel the kernel recipe file is the meta recipes kernel linux linux yocto_3 4 bb file Following is the default value for KBRANCH and the default override for the architectures the Yocto Project supports KBRANCH DEFAULT standard base KBRANCH KBRANCH DEFAULT This branch exists in the Linux yocto 3 4 kernel Git repository http git yoctoproject org cgit cgi linux yocto 3 4 refs heads This variable is also used from the kernel s append file to identify the kernel branch specific to a particular machine or target hardware The kernel s append file is located in the BSP layer for a given machine For example the kernel append file for the Crown Bay BSP is in the meta intel Git repository and is named meta crownbay recipes kernel linux linux yocto 3 4 bbappend Here are the related statements from the append file COMPATIBLE MACHINE crownbay crownbay KMACHINE crownbay crownbay KBRANCH crownbay standard crownbay COMPATIBLE MACHINE crownbay noemgd crownbay noemgd KMACHINE_crownbay noemgd crownbay KBRANCH crownbay noemg
114. he multiplier does not produce an image with all the theoretical free disk space See IMAGE ROOTFS SIZE for information on how the build system determines the overall image size The default 3096 free disk space typically gives the image enough room to boot and allows for basic post installs while still leaving a small amount of free disk space If 3096 free space is inadequate you can increase the default value For example the following setting gives you 5096 free space added to the image IMAGE OVERHEAD FACTOR 1 5 Alternatively you can ensure a specific amount of free disk space is added to the image by using IMAGE ROOTFS EXTRA SPACE the variable Defines additional free disk space created in the image in Kbytes By default this variable is set to 0 This free disk space is added to the image after the build system determines the image size as described in IMAGE ROOTFS SIZE This variable is particularly useful when you want to ensure that a specific amount of free disk space is available on a device after an image is installed and running For example to be sure 5 Gbytes of free disk space is available set the variable as follows IMAGE ROOTFS EXTRA SPACE 5242880 IMAGE_ROOTFS_SIZE Defines the size in Kbytes for the generated image The OpenEmbedded build system determines the final size for the generated image using an algorithm that takes into account the initial disk space used for the generated image a re
115. he output package contents re create the packages and construct the root filesystem This change is unlikely to cause any problems unless you have missing declared dependencies Scanning Directory Names When scanning for files in SRC URI the build system now uses FILESOVERRIDES instead of OVERRIDES for the directory names In general the values previously in OVERRIDES are now in FILESOVERRIDES as well However if you relied upon an additional value you previously added to OVERRIDES you might now need to add it to FILESOVERRIDES unless you are already adding it through the MACHINEOVERRIDES or DISTROOVERRIDES variables as appropriate For more related changes see the Variables section 4 2 3 Proxies and Fetching Source A new oe git proxy script has been added to replace previous methods of handling proxies and fetching source from Git See the meta yocto conf site conf sample file for information on how to use this script 4 2 4 Custom Interfaces File netbase change If you have created your own custom etc network interfaces file by creating an append file for the netbase recipe you now need to create an append file for the init ifupdown recipe instead which you can find in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory at meta recipes core init ifupdown For information on how to use append files see the Using bbappend Files http www yoctoproject org docs 1 4 2 dev
116. http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory Or the target can be the name of a recipe for a specific piece of software such as BusyBox For more details about the images the OpenEmbedded build system supports see the Images chapter Note Building an image without GNU General Public License Version 3 GPLv3 components is only supported for minimal and base images See the Images chapter for more information 2 1 2 Building an Image Using GPL Components When building an image using GPL components you need to maintain your original settings and not switch back and forth applying different versions of the GNU General Public License If you rebuild using different versions of GPL dependency errors might occur due to some components not being rebuilt 2 2 Installing and Using the Result Once an image has been built it often needs to be installed The images and kernels built by the OpenEmbedded build system are placed in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory in tmp deploy images For information on how to run pre built images such as qemux86 and qemuarm see the Using Pre Built Binaries and QEMU http www yoctoproject org docs 1 4 2 yocto project qs yocto project qs html using pre built section in the Yocto Project Quick Start For information about how to install these images see the documentation for your particular boa
117. http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory consists of several components Understanding them and knowing where they are located is key to using the Yocto Project well This chapter describes the Source Directory and gives information about the various files and directories For information on how to establish a local Source Directory on your development system see the Getting Set Up http www yoctoproject org docs 1 4 2 dev manual dev manual html getting setup section in the Yocto Project Development Manual Note The OpenEmbedded build system does not support file or directory names that contain spaces Be sure that the Source Directory you use does not contain these types of names 5 1 Top Level Core Components This section describes the top level components of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory 5 1 1 bitbake This directory includes a copy of BitBake for ease of use The copy usually matches the current stable BitBake release from the BitBake project BitBake a Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata interpreter reads the Yocto Project metadata and runs the tasks defined by that data Failures are usually from the metadata and not from BitBake itself Consequently most users do not need to worry about BitBake When you run the bitbake command the wrapper script in sc
118. ied logging domains P profile profile the command and print a report u UI ui UI userinterface to use t SERVERTYPE servertype SERVERTYPE Choose which server to use none process or xmlrpc revisions changed Set the exit code depending on whether upstream floating revisions have changed or not 6 7 Fetchers BitBake also contains a set of fetcher modules that allow retrieval of source code from various types of sources For example BitBake can get source code from a disk with the metadata from websites from remote shell accounts or from Source Code Management SCM systems like cvs subversion git Fetchers are usually triggered by entries in SRC_URI You can find information about the options and formats of entries for specific fetchers in the BitBake manual located in the bitbake doc manual directory of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory One useful feature for certain Source Code Manager SCM fetchers is the ability to auto update when the upstream SCM changes version Since this ability requires certain functionality from the SCM not all systems support it Currently Subversion Bazaar and to a limited extent Git support the ability to auto update This feature works using the SRCREV variable See the Using an External SCM http www yoctoproject org docs 1 4 2 dev manual dev manual html platdev appdev srcrev section in the Yocto Project Devel
119. ingpoky extend customimage imagefeatures section in the Yocto Project Development Manual Formats of root filesystem images that you want to have created Specifies the packages to install into an image The IMAGE_INSTALL variable is a mechanism for an image recipe and you should use it with care to avoid ordering issues Image recipes set IMAGE_INSTALL to specify the packages to install into an image through image bbclass Additionally helper classes exist such as core image bbclass that can take IMAGE FEATURES lists and turn these into auto generated entries in IMAGE_INSTALL in addition to its default contents Using IMAGE INSTALL with the operator from the conf local conf file or from within an image recipe is not recommended as it can cause ordering issues Since core image bbclass sets IMAGE_INSTALL to a default value using the operator using a operation against IMAGE_INSTALL will result in unexpected behavior when used in conf local conf Furthermore the same operation from with an image recipe may or may not succeed depending on the specific situation In both these cases the behavior is contrary to how most users expect the operator to work When you use this variable it is best to use it as follows IMAGE_LINGUAS IMAGE_OVERHEAD_FACTOR IMAGE_ROOTFS_EXTRA_SPACE IMAGE INSTALL append package name Be sure to include the space between the quotation character and the start of the package name
120. ironment Running this script with the source command in a shell makes changes to PATH and sets other core BitBake variables based on the current working directory You need to run this script before running BitBake commands The script uses other scripts within the scripts directory to do the bulk of the work By default running this script without a Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory argument creates the build directory If you provide a Build Directory argument when you source the script you direct OpenEmbedded build system to create a Build Directory of your choice For example the following command creates a Build Directory named mybuilds that is outside of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory source oe init build env mybuilds Note The OpenEmbedded build system does not support file or directory names that contain spaces If you attempt to run the oe init build env script from a Source Directory that contains spaces in either the filenames or directory names the script returns an error indicating no such file or directory Be sure to use a Source Directory free of names containing spaces 5 1 11 LICENSE README and README hardware These files are standard top level files 5 2 The Build Directory build The OpenEmbedded build system creates the Build Directory http www yoctoproject org
121. is preferred over a per recipe basis To help explain consider having the IPK packaging backend enabled and then switching to DEB In this case do_ install and do_package output are still valid However with a per recipe approach the build would not include the deb files Consequently you would have to invalidate the whole build and rerun it Rerunning everything is not the best situation Also in this case the core must be taught much about specific tasks This methodology does not scale well and does not allow users to easily add new tasks in layers or as external recipes without touching the packaged staging core 3 2 2 Checksums Signatures The shared state code uses a checksum which is a unique signature of a task s inputs to determine if a task needs to be run again Because it is a change in a task s inputs that triggers a rerun the process needs to detect all the inputs to a given task For shell tasks this turns out to be fairly easy because the build process generates a run shell script for each task and it is possible to create a checksum that gives you a good idea of when the task s data changes To complicate the problem there are things that should not be included in the checksum First there is the actual specific build path of a given task the WORKDIR It does not matter if the working directory changes because it should not affect the output for target packages Also the build process has the objective of making nat
122. itors disk space and available inodes during the build and allows you to control the build based on these parameters Disk space monitoring is disabled by default To enable monitoring add the BB DISKMON DIRS variable to your conf local conf file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory Use the following form BB_DISKMON DIRS lt action gt lt dir gt lt threshold gt where lt action gt is ABORT Immediately abort the build when a threshold is broken STOPTASKS Stop the build after the currently executing tasks have finished when a threshold is broken WARN Issue a warning but continue the build when a threshold is broken Subsequent warnings are issued as defined by the BB DISKMON WARNINTERVAL variable which must be defined in the conf local conf file dir is Any directory you choose You can specify one or more directories to monitor by separating the groupings with a space If two directories are on the same device only the first directory is monitored threshold is Either the minimum available disk space the minimum number of free inodes or both You must specify at least one To omit one or the other simply omit the value Specify the threshold using G M K for Gbytes Mbytes and Kbytes respectively If you do not specify G M or K Kbytes is assumed by default Do not use GB MB or KB Here are some examples
123. ive or cross packages relocatable The checksum therefore needs to exclude WORKDIR The simplistic approach for excluding the working directory is to set WORKDIR to some fixed value and create the checksum for the run script Another problem results from the run scripts containing functions that might or might not get called The incremental build solution contains code that figures out dependencies between shell functions This code is used to prune the run scripts down to the minimum set thereby alleviating this problem and making the run scripts much more readable as a bonus So far we have solutions for shell scripts What about Python tasks The same approach applies even though these tasks are more difficult The process needs to figure out what variables a Python function accesses and what functions it calls Again the incremental build solution contains code that first figures out the variable and function dependencies and then creates a checksum for the data used as the input to the task Like the WORKDIR case situations exist where dependencies should be ignored For these cases you can instruct the build process to ignore a dependency by using a line like the following PACKAGE ARCHS vardepsexclude MACHINE This example ensures that the PACKAGE ARCHS variable does not depend on the value of MACHINE even if it does reference it Equally there are cases where we need to add dependencies BitBake is not able to find You
124. l modules package installs all packages with modules and various other kernel packages such as kernel vmlinux Various other classes are used by the kernel and module classes internally including kernel arch bbclass module strip bbclass module base bbclass and linux kernel base bbclass 7 15 Creating Images image bbclass and rootfs bbclass These classes add support for creating images in several formats First the root filesystem is created from packages using one of the rootfs bbclass files depending on the package format used and then the image is created The IMAGE FSTYPES variable controls the types of images to generate The IMAGE INSTALL variable controls the list of packages to install into the image 7 16 Host System Sanity Checks sanity bbclass This class checks to see if prerequisite software is present on the host system so that users can be notified of potential problems that might affect their build The class also performs basic user configuration checks from the local conf configuration file to prevent common mistakes that cause build failures Distribution policy usually determines whether to include this class 7 17 Generated Output Quality Assurance Checks insane bbclass This class adds a step to the package generation process that sanity checks the packages generated by the OpenEmbedded build system A range of checks are performed that check the build s output for common problems that show up d
125. ld also enable all the other packages with LICENSE FLAGS containing commercial which you may or may not want LICENSE FLAGS WHITELIST commercial Specifying audio and video plug ins as part of the COMMERCIAL AUDIO PLUGINS and COMMERCIAL VIDEO PLUGINS statements or commercial Qt components as part of the COMMERCIAL QT statement along with the enabling LICENSE FLAGS WHITELIST includes the plug ins or components into built images thus adding support for media formats or components Chapter 4 Migrating to a Newer Yocto Project Release This chapter provides information you can use to migrate work to a newer Yocto Project release You can find the same information in the release notes for a given release 4 1 Moving to the Yocto Project 1 3 Release This section provides migration information for moving to the Yocto Project 1 3 Release from the prior release 4 1 1 Local Configuration Differences include changes for SSTATE_MIRRORS and bblayers conf 4 1 1 1 SSTATE_MIRRORS The shared state cache sstate cache as pointed to by SSTATE DIR by default now has two character subdirectories to prevent issues rising from too many files in the same directory Also native sstate cache packages will go into a subdirectory named using the distro ID string If you copy the newly structured sstate cache to a mirror location either local or remote and then point to it in SSTATE_MIRRORS you need to append PATH to the end of the mirror URL
126. ll devshell bbclass This class adds the devshell task Distribution policy dictates whether to include this class See the Using a Development Shell http www yoctoproject org docs 1 4 2 dev manual dev manual html platdev appdev devshell section in the Yocto Project Development Manual for more information about using devshell 7 12 Package Groups packagegroup bbclass This class sets default values appropriate for package group recipes e g PACKAGES PACKAGE ARCH ALLOW EMPTY and so forth It is highly recommended that all package group recipes inherit this class For information on how to use this class see the Customizing Images Using Custom Package Groups http www yoctoproject org docs 1 4 2 dev manual dev manual html usingpoky extend customimage customtasks section in the Yocto Project Development Manual Previously this class was named task bbclass 7 13 Packaging package bbclass The packaging classes add support for generating packages from a build s output The core generic functionality is in package bbclass The code specific to particular package types is contained in various sub classes such as package deb bbclass package ipk bbclass and package rpm bbclass Most users will want one or more of these classes You can control the list of resulting package formats by using the PACKAGE CLASSES variable defined in the local conf configuration file which is located in the conf folder of the Source Directory ht
127. lopers who wish to disable the new features need to be able to selectively prevent the backfilling from occurring They can do this by adding the undesired feature or features to the DISTRO FEATURES BACKFILL CONSIDERED or MACHINE FEATURES BACKFILL CONSIDERED variables for distro features and machine features respectively Here are two examples to help illustrate feature backfilling The pulseaudio distro feature option Previously PulseAudio support was enabled within the Qt and GStreamer frameworks Because of this the feature is backfilled and thus enabled for all distros through the DISTRO FEATURES BACKFILL variable in the meta conf bitbake conf file However your distro needs to disable the feature You can disable the feature without affecting other existing distro configurations that need PulseAudio support by adding pulseaudio to DISTRO FEATURES BACKFILL CONSIDERED in your distro s conf file Adding the feature to this variable when it also exists in the DISTRO FEATURES BACKFILL variable prevents the build system from adding the feature to your configuration s DISTRO_FEATURES effectively disabling the feature for that particular distro The rtc machine feature option Previously real time clock RTC support was enabled for all target devices Because of this the feature is backfilled and thus enabled for all machines through the MACHINE FEATURES BACKFILL variable in the meta conf bitbake conf file However your target device d
128. manual dev manual html using bbappend files in the Yocto Project Development Manual 4 2 5 Remote Debugging Support for remote debugging with the Eclipse IDE is now separated into an image feature eclipse debug that corresponds to the packagegroup core eclipse debug package group Previously the debugging feature was included through the tools debug image feature which corresponds to the packagegroup core tools debug package group 4 2 6 Variables The following variables have changed SANITY TESTED DISTROS This variable now uses a distribution ID which is composed of the host distributor ID followed by the release Previously SANITY TESTED DISTROS was composed of the description field For example Ubuntu 12 10 becomes Ubuntu 12 10 You do not need to worry about this change if you are not specifically setting this variable or if you are specifically setting it to SRC URI The PN PF P and FILE DIRNAME directories have been dropped from the default value of the FILESPATH variable which is used as the search path for finding files referred to in SRC URI If you have a recipe that relied upon these directories which would be unusual then you will need to add the appropriate paths within the recipe or alternatively rearrange the files The most common locations are still covered by BP BPN and files which all remain in the default value of FILESPATH 4 2 7 Target Package Management with RPM If r
129. me For the remainder you can now find them in the meta extras repository which is in the Yocto Project Source Repositories http www yoctoproject org docs 1 4 2 dev manual dev manual html source repositories 4 2 Moving to the Yocto Project 1 4 Release This section provides migration information for moving to the Yocto Project 1 4 Release from the prior release 4 2 1 BitBake Differences include the following Comment Continuation If a comment ends with a line continuation character then the next line must also be a comment Any instance where this is not the case now triggers a warning You must either remove the continuation character or be sure the next line is a comment Package Name Overrides The runtime package specific variables RDEPENDS RRECOMMENDS RSUGGESTS RPROVIDES RCONFLICTS RREPLACES FILES ALLOW EMPTY and the pre post install and uninstall script functions pkg preinst pkg postinst pkg prerm and pkg postrm should always have a package name override For example use RDEPENDS PNj for the main package instead of RDEPENDS BitBake uses more strict checks when it parses recipes 4 2 2 Build Behavior Differences include the following Shared State Code The shared state code has been optimized to avoid running unnecessary tasks For example bitbake c rootfs some image from shared state no longer populates the target sysroot since that is not necessary Instead the system just needs to extract t
130. ment of rich and animated graphical user interfaces core image gtk directfb An image that uses gtk over directfb instead of X11 In order to build this image requires specific distro configuration that enables gtk over directfb core image x11 A very basic X11 image with a terminal qt4e demo image An image that launches into the demo application for the embedded not based on X11 version of Qt core image rt A core image minimal image plus a real time test suite and tools appropriate for real time use core image rt sdk A core image rt image that includes everything in meta toolchain The image also includes development headers and libraries to form a complete stand alone SDK and is suitable for development using the target core image sato An image with Sato support a mobile environment and visual style that works well with mobile devices The image supports X11 with a Sato theme and applications such as a terminal editor file manager media player and so forth core image sato dev A core image sato image suitable for development using the host The image includes libraries needed to build applications on the device itself testing and profiling tools and debug symbols This image was formerly core image sdk core image sato sdk A core image sato image that includes everything in meta toolchain The image also includes development headers and libraries to form a complete standalone SDK and is suitable for development usin
131. mizations fomit frame pointer frename registers O2 H HOMEPAGE HOST_SYS IMAGE_FEATURES IMAGE_FSTYPES IMAGE_INSTALL Website where more information about the software the recipe is building can be found Specifies the system including the architecture and the operating system for with the build is occurring in the context of the current recipe The OpenEmbedded build system automatically sets this variable You do not need to set the variable yourself Here are two examples Given a native recipe on a 32 bit x86 machine running Linux the value is i686 linux Given a recipe being built for a little endian MIPS target running Linux the value might be mipsel linux The primary list of features to include in an image Typically you configure this variable in an image recipe Although you can use this variable from your local conf file which is found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory best practices dictate that you do not Note To enable extra features from outside the image recipe use the EXTRA IMAGE FEATURES variable For a list of image features that ships with the Yocto Project see the Images section For example that shows how to customize your image by using this variable see the Customizing Images Using Custom IMAGE FEATURES and EXTRA IMAGE FEATURES http www yoctoproject org docs 1 4 2 dev manual dev manual html us
132. ml source directory TMPDIR TOPDIR tmp This variable is the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory BitBake automatically sets this variable The OpenEmbedded build system uses the Build Directory when building images W WORKDIR The pathname of the working directory in which the OpenEmbedded build system builds a recipe This directory is located within the TMPDIR directory structure and changes as different packages are built The actual WORKDIR directory depends on several things The temporary directory TMPDIR The package architecture PACKAGE ARCH The target machine MACHINE The target operating system TARGET 0S The recipe name PN The recipe version PV The recipe revision PR For packages that are not dependent on a particular machine WORKDIR is defined as follows TMPDIR work PACKAGE ARCH poky TARGET 0S PN PV PR As an example assume a Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory top level folder name poky and a default Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory at poky build In this case the working directory the build system uses to build the v86d package is the following poky build tmp work qemux86 poky linux v86d 01 9 r0 For packages that are dependent on a particular machin
133. mmon file named meta conf machine include qemu inc that prepends MACHINEOVERRIDES with the following variable override MACHINEOVERRIDES qemuall Applying an override like qemuall affects all QEMU emulated machines elsewhere Here is an example from the connman conf recipe SRC URI append gemuall file wired config file wired setup MAINTAINER The email address of the distribution maintainer MIRRORS Specifies additional paths from which the OpenEmbedded build system gets source code When the build system searches for source MLPREFIX MODULE_TARBALL_DEPLOY MULTIMACH_TARGET_SYS N NATIVELSBSTRING O OE_TERMINAL code it first tries the local download directory If that location fails the build system tries locations defined by PREMIRRORS the upstream source and then locations specified by MIRRORS in that order Assuming your distribution DISTRO is poky the default value for MIRRORS is defined in the conf distro poky conf file in the meta yocto Git repository Specifies a prefix has been added to PN to create a special version of a recipe or package such as a Multilib version The variable is used in places where the prefix needs to be added to or removed from a the name e g the BPN variable MLPREFIX gets set when a prefix has been added to PN Controls creation of the modules tgz file Set this variable to 0 to disable creation of this file which contains all of the kernel modules
134. n an error occurs the target that failed and those that depend on it cannot be remade However when you use this option other dependencies can still be processed 3 1 2 Metadata Recipes The bb files are usually referred to as recipes In general a recipe contains information about a single piece of software The information includes the location from which to download the source patches if any are needed which special configuration options to apply how to compile the source files and how to package the compiled output The term package can also be used to describe recipes However since the same word is used for the packaged output from the OpenEmbedded build system i e ipk or deb files this document avoids using the term package when referring to recipes 3 1 3 Classes Class files bbclass contain information that is useful to share between Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata files An example is the Autotools class which contains common settings for any application that Autotools uses The Classes chapter provides details about common classes and how to use them 3 1 4 Configuration The configuration files conf define various configuration variables that govern the OpenEmbedded build process These files fall into several areas that define machine configuration options distribution configuration options compiler tuning options general common configur
135. n mailing list about OpenEmbedded Core the core metadata http lists linuxtogo org cgi bin mailman listinfo openembedded devel Discussion mailing list about OpenEmbedded http lists linuxtogo org cgi bin mailman listinfo bitbake devel Discussion mailing list about the BitBake http www yoctoproject org docs 1 4 2 dev manual dev manual html bitbake term build tool http lists yoctoproject org listinfo poky Discussion mailing list about Poky http www yoctoproject org docs 1 4 2 dev manual dev manual html poky http lists yoctoproject org listinfo yocto announce Mailing list to receive official Yocto Project release and milestone announcements 13 4 Internet Relay Chat IRC Two IRC channels on freenode are available for the Yocto Project and Poky discussions yocto poky 13 5 Links Here is a list of resources you will find helpful The Yocto Project website http www yoctoproject org The home site for the Yocto Project Intel Corporation http www intel com The company who acquired OpenedHand in 2008 and began development on the Yocto Project OpenEmbedded http www openembedded org The upstream generic embedded distribution used as the basis for the build system in the Yocto Project Poky derives from and contributes back to the OpenEmbedded project BitBake http developer berlios de projects bitbake The tool used to process metadata BitBake User Manual A compr
136. n this list is not found As an example suppose the machine for which you are building requires example init to be run during boot to initialize the hardware In this case you would use the following in the machine s conf configuration file MACHINE ESSENTIAL EXTRA RDEPENDS example init MACHINE ESSENTIAL EXTRA RRECOMMENDS A list of recommended machine specific packages to install as part of the image being built The build process does not depend on these packages being present However because this is a machine essential variable the list of packages are essential for the machine to boot The impact ofthis variable affects images based on packagegroup core boot including the core image minimal image This variable is similar to the MACHINE ESSENTIAL EXTRA RDEPENDS variable with the exception that the image being built does not have a build dependency on the variable s list of packages In other words the image will still build if a package in this list is not found Typically this variable is used to handle essential kernel modules whose functionality may be selected to be built into the kernel rather than as a module in which case a package will not be produced Consider an example where you have a custom kernel where a specific touchscreen driver is required for the machine to be usable However the driver can be built as a module or into the kernel depending on the kernel configuration If the driver is built as a mo
137. n use FILESEXTRAPATHS prepend THISDIR files In this example the build system extends the FILESPATH variable to include a directory named files that is in the same directory as the corresponding append file Here is a final example that specifically adds three paths FILESEXTRAPATHS prepend path 1 path 2 path 3 By prepending paths in bbappend files you allow multiple append files that reside in different layers but are used for the same recipe to correctly extend the path Note Be sure to use the immediate expansion operator and include the trailing separating colon character FILESPATH The default set of directories the OpenEmbedded build system uses when searching for patches and files During the build process BitBake searches each directory in FILESPATH in the specified order when looking for files and patches specified by each file URI in a recipe The default value for the FILESPATH variable is defined in the base bbclass class found in meta classes in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory FILESPATH base set filespath FILE DIRNAME BP FILE DIRNAME BPN FILE DIRNAME files d Note Do not hand edit the FILESPATH variable Be aware that the default FILESPATH directories do not map to directories in custom layers where append files bbappend are used If you want the build system to find pa
138. ng boot nfs Include NFS client support for mounting NFS exports on device pci Include PCI bus support pcmcia Include PCMCIA CompactFlash support ppp Include PPP dialup support smbfs Include SMB networks client support for mounting Samba Microsoft Windows shares on device systemd Include support for this init manager which is a full replacement of for init with parallel starting of services reduced shell overhead and other features This init manager is used by many distributions usbgadget Include USB Gadget Device support for USB networking serial storage usbhost Include USB Host support allows to connect external keyboard mouse storage network etc wayland Include the Wayland display server protocol and the library that supports it wifi Include WiFi support integrated only 9 2 Machine The items below are features you can use with MACHINE FEATURES Features do not have a one to one correspondence to packages and they can go beyond simply controlling the installation of a package or packages Sometimes a feature can influence how certain recipes are built For example a feature might determine whether a particular configure option is specified within do configure for a particular recipe This feature list only represents features as shipped with the Yocto Project metadata acpi Hardware has ACPI x86 x86 64 only alsa Hardware has ALSA audio drivers apm Hardware uses APM or A
139. nside the include files that the recipes share and then expand the INC PR variable within the recipes to help define the recipe revision The following provides an example that shows how to use the INC PR variable given a common include file that defines the variable Once the variable is defined in the include file you can use the variable to set the PR values in each recipe You will notice that when you set a recipe s PR you can provide more granular revisioning by appending values to the INC PR variable recipes graphics xorg font xorg font common inc INC PR r2 recipes graphics xorg font encodings 1 0 4 bb PR INC_PR 1 recipes graphics xorg font font util 1 3 0 bb PR INC_PR 0 recipes graphics xorg font font alias 1 0 3 bb PR INC_PR 3 INHIBIT_PACKAGE_STRIP INHERIT INITSCRIPT_PACKAGES INITSCRIPT_NAME INITSCRIPT_PARAMS INSANE_SKIP KARCH The first line of the example establishes the baseline revision to be used for all recipes that use the include file The remaining lines in the example are from individual recipes and show how the PR value is set If set to 1 causes the build to not strip binaries in resulting packages Causes the named class to be inherited at this point during parsing The variable is only valid in configuration files A list of the packages that contain initscripts If multiple packages are specified you need to append the package name to the other INITSCRIPT as an ove
140. nsists of a set of tasks The standard BitBake behavior in most cases is fetch unpack patch configure compile install package package write and build The default task is build and any tasks on which it depends build first Some tasks exist such as devshell that are not part of the default build chain If you wish to run a task that is not part of the default build chain you can use the c option in BitBake Here is an example bitbake matchbox desktop c devshell If you wish to rerun a task use the f force option For example the following sequence forces recompilation after changing files in the working directory bitbake matchbox desktop make some changes to the source code in the working directory bitbake matchbox desktop c compile f bitbake matchbox desktop This sequence first builds and then recompiles matchbox desktop The last command reruns all tasks basically the packaging tasks after the compile BitBake recognizes that the compile task was rerun and therefore understands that the other tasks also need to be run again You can view a list of tasks in a given package by running the listtasks task as follows bitbake matchbox desktop c listtasks The results are in the file WORKDIR temp log do listtasks 2 3 3 Dependency Graphs Sometimes it can be hard to see why BitBake wants to build some other packages before a given package you have specified The bitbake g targetname command creates the
141. ntains any end result output from the OpenEmbedded build process 5 2 11 build tmp deploy deb This directory receives any deb packages produced by the build process The packages are sorted into feeds for different architecture types 5 2 12 build tmp deploy rpm This directory receives any rpm packages produced by the build process The packages are sorted into feeds for different architecture types 5 2 13 build tmp deploy licenses This directory receives package licensing information For example the directory contains sub directories for bash busybox and eglibc among others that in turn contain appropriate COPYING license files with other licensing information For information on licensing see the Maintaining Open Source License Compliance During Your Product s Lifecycle http www yoctoproject org docs 1 4 2 dev manual dev manual html maintaining open source license compliance during your products lifecycle section 5 2 14 build tmp deploy images This directory receives complete filesystem images If you want to flash the resulting image from a build onto a device look here for the image Be careful when deleting files in this directory You can safely delete old images from this directory e g core image hob image etc However the kernel zImage uImage etc bootloader and other supplementary files might be deployed here prior to building an image Because these files are not directly produced
142. nual html metadata change that changes the task hash automatically causing the task to be run again This removes the need to bump PR values and changes to Metadata automatically ripple across the build It is also worth noting that the end result of these signature generators is to make some dependency and hash information available to the build This information includes BB BASEHASH task lt taskname gt the base hashes for each task in the recipe BB BASEHASH filename taskname the base hashes for each dependent task BBHASHDEPS filename taskname The task dependencies for each task BB TASKHASH the hash of the currently running task 3 2 3 Shared State Checksums and dependencies as discussed in the previous section solve half the problem The other part of the problem is being able to use checksum information during the build and being able to reuse or rebuild specific components The shared state class sstate bbclass is a relatively generic implementation of how to capture a snapshot of a given task The idea is that the build process does not care about the source of a task s output Output could be freshly built or it could be downloaded and unpacked from somewhere the build process does not need to worry about its source There are two types of output one is just about creating a directory in WORKDIR A good example is the output of either do installor do package The other type of output occurs when a set of data
143. o pick up files specified through a SRC URI statement from your append file you need to be sure to extend the FILESPATH variable by also using the FILESEXTRAPATHS variable from within your append file bzr Fetches files from a Bazaar revision control repository git Fetches files from a Git revision control repository osc Fetches files from an OSC OpenSUSE Build service revision control repository repo Fetches files from a repo Git repository svk Fetches files from an SVK revision control repository http Fetches files from the Internet using http https Fetches files from the Internet using https ftp Fetches files from the Internet using ftp cvs Fetches files from a CVS revision control repository hg Fetches files from a Mercurial hg revision control repository p4 Fetches files from a Perforce p4 revision control repository ssh Fetches files from a secure shell svn Fetches files from a Subversion svn revision control repository Standard and recipe specific options for SRC_URI exist Here are standard options apply Whether to apply the patch or not The default action is to apply the patch striplevel Which striplevel to use when applying the patch The default level is 1 Here are options specific to recipes building code from a revision control system e mindate Apply the patch only if SRCDATE is equal to or greate
144. ocs 1 4 2 dev manual dev manual html creating a read only root filesystem section in the Yocto Project Development Manual for more information splash Enables showing a splash screen during boot By default this screen is provided by psplash which does allow customization If you prefer to use an alternative splash screen package you can do so by setting the SPLASH variable to a different package name or names within the image recipe or at the distro configuration level ssh server dropbear Installs the Dropbear minimal SSH server ssh server openssh Installs the OpenSSH SSH server which is more full featured than Dropbear Note that if both the OpenSSH SSH server and the Dropbear minimal SSH server are present in IMAGE FEATURES then OpenSSH will take precedence and Dropbear will not be installed staticdev pkgs Installs static development packages i e static libraries containing a files for all packages installed in a given image tools debug Installs debugging tools such as strace and gdb For information on GDB see the Debugging With the GNU Project Debugger GDB Remotely http www yoctoproject org docs 1 4 2 dev manual dev manual html platdev gdb remotedebug section in the Yocto Project Development Manual For information on tracing and profiling see the Yocto Project Profiling and Tracing Manual http www yoctoproject org docs 1 4 2 profile manual profile manual html tools profile Installs profiling tool
145. oes not have this capability You can disable RTC support for your device without affecting other machines that need RTC support by adding the feature to your machine s MACHINE FEATURES BACKFILL CONSIDERED list in the machine s conf file Adding the feature to this variable when it also exists in the MACHINE FEATURES BACKFILL variable prevents the build system from adding the feature to your configuration s MACHINE FEATURES effectively disabling RTC support for that particular machine Chapter 10 Variables Glossary This chapter lists common variables used in the OpenEmbedded build system and gives an overview of their function and contents Glossary ABCDEFHIKLMOPRSTW A ALLOW_EMPTY AUTHOR AUTOREV BAD_RECOMMENDATIONS Specifies if an output package should still be produced if it is empty By default BitBake does not produce empty packages This default behavior can cause issues when there is an RDEPENDS or some other runtime hard requirement on the existence of the package Like all package controlling variables you must always use them in conjunction with a package name override Here is an example ALLOW EMPTY PN 1 The email address used to contact the original author or authors in order to send patches and forward bugs When SRCREV is set to the value of this variable it specifies to use the latest source revision in the repository Here is an example SRCREV AUTOREV The Build Directory http
146. oid unnecessarily rebuilding tasks As with all schemes this one has some drawbacks It is possible that you could make implicit changes that are not factored into the checksum calculation but do affect a task s output A good example is perhaps when a tool changes its output Assume that the output of rpmdeps needed to change The result of the change should be that all the package package write rpm and package _deploy rpm shared state cache items would become invalid But because this is a change that is external to the code and therefore implicit the associated shared state cache items do not become invalidated In this case the build process uses the cached items rather than running the task again Obviously these types of implicit changes can cause problems To avoid these problems during the build you need to understand the effects of any change you make Note that any changes you make directly to a function automatically are factored into the checksum calculation and thus will invalidate the associated area of sstate cache You need to be aware of any implicit changes that are not obvious changes to the code and could affect the output of a given task Once you are aware of such changes you can take steps to invalidate the cache and force the tasks to run The steps to take are as simple as changing function s comments in the source code For example to invalidate package shared state files change the comment statements of do_package or
147. oky extend customimage imagefeatures section in the Yocto Project Development Manual A list of recipes to build that do not provide packages for installing into the root filesystem Sometimes a recipe is required to build the final image but is not needed in the root filesystem You can use the EXTRA_IMAGEDEPENDS variable to list these recipes and thus specify the dependencies A typical example is a required bootloader in a machine configuration Note To add packages to the root filesystem see the various RDEPENDS and RRECOMMENDS variables Additional cmake options Additional configure script options Additional GNU make options The list of directories or files that are placed in packages To use the FILES variable provide a package name override that identifies the resulting package Then provide a space separated list of files or paths that identifies the files you want included as part of the resulting package Here is an example FILES PN bindir mydirl bindir mydir2 myfile Note When specifying paths as part of the FILES variable it is good practice to use appropriate path variables For example sysconfdir rather than etc or bindir rather than usr bin You can find a list of these variables at the top of the meta conf bitbake conf file in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory If some of the files you provide wit
148. opment Manual for more information Chapter 7 Classes Class files are used to abstract common functionality and share it amongst multiple bb files Any Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata usually found in a bb file can also be placed in a class file Class files are identified by the extension bbclass and are usually placed in a classes directory beneath the meta directory found in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory Class files can also be pointed to by BUILDDIR e g build in the same way as conf files in the conf directory Class files are searched for in BBPATH using the same method by which conf files are searched In most cases inheriting the class is enough to enable its features although for some classes you might need to set variables or override some of the default behavior This chapter discusses only the most useful and important classes Other classes do exist within the meta classes directory in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory You can reference the bbclass files directly for more information 7 1 The base Class base bbclass The base class is special in that every bb file inherits it automatically This class contains definitions for standard basic tasks such as fetching unpacking configuring empty by default compilin
149. other machines If a mirror uses the same structure as SSTATE_DIR you need to add PATH at the end as shown in the examples below The build system substitutes the correct path within the directory structure SSTATE MIRRORS file http someserver tld share sstate PATH An file file some local dir sstate PATH STAGING_KERNEL_DIR The directory with kernel headers that are required to build out of tree modules STAMP Specifies the base path used to create recipe stamp files The path to an actual stamp file is constructed by evaluating this string and then appending additional information Currently the default assignment for STAMP as set in the meta conf bitbake conf file is STAMP STAMPS DIR MULTIMACH TARGET SYS PN EXTENDPE See STAMPS DIR MULTIMACH TARGET SYS PN EXTENDPE PV and PR for related variable information STAMPS_DIR Specifies the base directory in which the OpenEmbedded build system places stamps The default directory is TMPDIR stamps SUMMARY The short 72 characters or less summary of the binary package for packaging systems such as opkg rpm or dpkg By default SUMMARY is used to define the DESCRIPTION variable if DESCRIPTION is not set in the recipe SYSROOT_PREPROCESS FUNCSA list of functions to execute after files are staged into the sysroot These functions are usually used to apply additional processing on the staged files or to stage additional files T This vari
150. ovals Behind the scenes the shared state code works by looking in SSTATE DIR and SSTATE MIRRORS for shared state files Here is an example SSTATE MIRRORS file http someserver tld share sstate PATH An file file some local dir sstate PATH Note The shared state directory SSTATE DIR is organized into two character subdirectories where the subdirectory names are based on the first two characters of the hash If the shared state directory structure for a mirror has the same structure as SSTATE DIR you must specify PATH as part of the URI to enable the build system to map to the appropriate subdirectory The shared state package validity can be detected just by looking at the filename since the filename contains the task checksum or signature as described earlier in this section If a valid shared state package is found the build process downloads it and uses it to accelerate the task The build processes use the setscene tasks for the task acceleration phase BitBake goes through this phase before the main execution code and tries to accelerate any tasks for which it can find shared state packages If a shared state package for a task is available the shared state package is used This means the task and any tasks on which it is dependent are not executed As a real world example the aim is when building an IPKbased image only the do package write ipk tasks would have their shared state packages fetched and e
151. owing example uses a complete regular expression to tell BitBake to ignore all recipe and recipe append files in the meta ti recipes misc directory BBMASK meta ti recipes misc If you want to mask out multiple directories or recipes use the vertical bar to separate the regular expression fragments This next example masks out multiple directories and individual recipes BBMASK meta ti recipes misc meta ti recipes ti packagegroup BBMASK meta oe recipes support BBMASK openldap BBMASK opencv BBMASK lzma Notice how the vertical bar is used to append the fragments Note When specifying a directory name use the trailing slash character to ensure you match just that directory name BB NUMBER THREADS The maximum number of tasks BitBake should run in parallel at any one time If your host development system supports multiple cores a good rule of thumb is to set this variable to twice the number of cores BBFILE_COLLECTIONS BBFILE_PATTERN BBFILE_PRIORITY BBFILES BBPATH BBINCLUDELOGS BBLAYERS BBLAYERS_NON_REMOVABLE Lists the names of configured layers These names are used to find the other BBFILE variables Typically each layer will append its name to this variable in its conf layer conf file Variable that expands to match files from BBFILES in a particular layer This variable is used in the conf layer conf file and must be suffixed with the name of the specific la
152. parsed BitBake starts to build the target core image sato in the previous section s example and looks for providers of that target Once a provider is selected BitBake resolves all the dependencies for the target In the case of core image sato it would lead to packagegroup core x11 sato which in turn leads to recipes like matchbox terminal pcmanfm and gthumb These recipes in turn depend on eglibc and the toolchain Sometimes a target might have multiple providers A common example is virtual kernel which is provided by each kernel package Each machine often selects the best kernel provider by using a line similar to the following in the machine configuration file PREFERRED PROVIDER virtual kernel linux yocto The default PREFERRED PROVIDER is the provider with the same name as the target Understanding how providers are chosen is made complicated by the fact that multiple versions might exist BitBake defaults to the highest version of a provider Version comparisons are made using the same method as Debian You can use the PREFERRED_VERSION variable to specify a particular version usually in the distro configuration You can influence the order by using the DEFAULT PREFERENCE variable By default files have a preference of 0 Setting the DEFAULT_PREFERENCE to 1 makes the package unlikely to be used unless it is explicitly referenced Setting the DEFAULT_PREFERENCE to 1 makes it likely the package is used PREFERRED_VERSION
153. patched You will see this error on these types of distributions Switch to GNU Make 3 81 or patch your make to solve the problem 2 3 6 Building with No Dependencies If you really want to build a specific bb file you can use the command form bitbake b somepath somefile bb gt This command form does not check for dependencies so you should use it only when you know its dependencies already exist You can also specify fragments of the filename In this case BitBake checks for a unique match 2 3 7 Variables You can use the e BitBake option to display the resulting environment for a configuration when you do not specify a package or for a specific package when you do specify the package If you want to show the environment resulting from parsing a single recipe use the b recipename form 2 3 8 Recipe Logging Mechanisms Best practices exist while writing recipes that both log build progress and act on build conditions such as warnings and errors Both Python and Bash language bindings exist for the logging mechanism e Python For Python functions BitBake supports several loglevels bb fatal bb error bb warn bb note bb plain and bb debug Bash For Bash functions the same set of loglevels exist and are accessed with a similar syntax bbfatal bberror bbwarn bbnote bbplain and bbdebug For guidance on how logging is handled in both Python and Bash recipes see the Logging bbclass file in the meta classes folder of
154. pendencies and handles metadata that consists of variables in a certain format that get passed to the tasks 6 1 Parsing BitBake parses configuration files classes and bb files The first thing BitBake does is look for the bitbake conf file This file resides in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory within the meta conf directory BitBake finds it by examining its BBPATH environment variable and looking for the meta conf directory The bitbake conf file lists other configuration files to include from a conf directory below the directories listed in BBPATH In general the most important configuration file from a user s perspective is local conf which contains a user s customized settings for the OpenEmbedded build environment Other notable configuration files are the distribution configuration file set by the DISTRO variable and the machine configuration file set by the MACHINE variable The DISTRO and MACHINE BitBake environment variables are both usually set in the local conf file Valid distribution configuration files are available in the meta conf distro directory and valid machine configuration files in the meta conf machine directory Within the meta conf machine include directory are various tune inc configuration files that provide common tuning settings specific to and shared between particular architectures and machines After the parsing of the con
155. ptional dependency on another library which is auto detected If that library has already been built when the software is building the software will link to the built library and that library will be pulled into your image along with the new software even if you did not want the library The buildhistory class exists to help you maintain the quality of your build output You can use the class to highlight unexpected and possibly unwanted changes in the build output When you enable build history it records information about the contents of each package and image and then commits that information to a local Git repository where you can examine the information The remainder of this section describes the following How you can enable and disable build history How to understand what the build history contains How to limit the information used for build history How to examine the build history from both a command line and web interface 2 4 1 Enabling and Disabling Build History Build history is disabled by default To enable it add the following statements to the end of your conf local conf file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory INHERIT buildhistory BUILDHISTORY COMMIT 1 Enabling build history as previously described causes the build process to collect build output information and commit it to a local Git http www yoctoproject org docs 1 4 2
156. quested size for the image and requested additional free disk space to be added to the image Programatically the build system determines the final size of the generated image as follows if image du overhead lt rootfs size internal rootfs size rootfs size xspace else internal rootfs size image du overhead xspace where Returned value of the du command on the image image du overhead IMAGE OVERHEAD FACTOR rootfs size IMAGE ROOTFS SIZE internal rootfs size Initial root filesystem size before any modifications xspace IMAGE ROOTFS EXTRA SPACE See the IMAGE OVERHEAD FACTOR and IMAGE ROOTFS EXTRA SPACE variables for related information INC PR Helps define the recipe revision for recipes that share a common include file You can think of this variable as part of the recipe revision as set from within an include file Suppose for example you have a set of recipes that are used across several projects And within each of those recipes the revision its PR value is set accordingly In this case when the revision of those recipes changes the burden is on you to find all those recipes and be sure that they get changed to reflect the updated version of the recipe In this scenario it can get complicated when recipes that are used in many places and provide common functionality are upgraded to a new revision A more efficient way of dealing with this situation is to set the INC PR variable i
157. r than mindate maxdate Apply the patch only if SRCDATE is not later than mindate minrev Apply the patch only if SRCREV is equal to or greater than minrev maxrev Apply the patch only if SRCREV is not later than maxrev rev Apply the patch only if SRCREV is equal to rev notrev Apply the patch only if SRCREV is not equal to rev Here are some additional options worth mentioning unpack Controls whether or not to unpack the file if it is an archive The default action is to unpack the file subdir Places the file or extracts its contents into the specified subdirectory of WORKDIR This option is useful for unusual tarballs or other archives that do not have their files already in a subdirectory within the archive name Specifies a name to be used for association with SRC URI checksums when you have more than one file specified in SRC_URI downloadfilename Specifies the filename used when storing the downloaded file SRC URI OVERRIDES PACKAGE ARCH SRCDATE SRCPV SRCREV SSTATE DIR SSTATE MIRRORS By default the OpenEmbedded build system automatically detects whether SRC URI contains files that are machine specific If so the build system automatically changes PACKAGE ARCH Setting this variable to O disables this behavior The date of the source code used to build the package This variable applies only if the source was fetched from a Source Code Manager SCM Returns the
158. rd or machine 2 3 Debugging Build Failures The exact method for debugging build failures depends on the nature of the problem and on the system s area from which the bug originates Standard debugging practices such as comparison against the last known working version with examination of the changes and the re application of steps to identify the one causing the problem are valid for the Yocto Project just as they are for any other system Even though it is impossible to detail every possible potential failure this section provides some general tips to aid in debugging For discussions on debugging see the Debugging With the GNU Project Debugger GDB Remotely http www yoctoproject org docs 1 4 2 dev manual dev manual html platdev gdb remotedebug and Working within Eclipse http www yoctoproject org docs 1 4 2 dev manual dev manual html adt eclipse sections in the Yocto Project Development Manual 2 3 1 Task Failures The log file for shell tasks is available in WORKDIR temp log do taskname pid For example the compile task for the QEMU minimal image for the x86 machine qemux86 might be tmp work qemux86 poky linux core image minimal 1 0 r0 temp log do compile 20830 To see what BitBake runs to generate that log look at the corresponding run do taskname pid file located in the same directory Presently the output from Python tasks is sent directly to the console 2 3 2 Running Specific Tasks Any given package co
159. re making your decision on package manager however you should consider some further things about using RPM RPM starts to provide more abilities than IPK due to the fact that it processes more metadata For example this information includes individual file types file checksum generation and evaluation on install sparse file support conflict detection and resolution for Multilib systems ACID style upgrade and repackaging abilities for rollbacks For smaller systems the extra space used for the Berkley Database and the amount of metadata when using RPM can affect your ability to perform on device upgrades You can find additional information on the effects of the package class at these two Yocto Project mailing list links https lists yoctoproject org pipermail poky 2011 May 006362 html http lists yoctoproject org pipermail poky 2011 May 006362 html https lists yoctoproject org pipermail poky 2011 May 006363 html http lists yoctoproject org pipermail poky 2011 May 006363 html 7 14 Building Kernels kernel bbclass This class handles building Linux kernels The class contains code to build all kernel trees All needed headers are staged into the STAGING KERNEL DIR directory to allow out of tree module builds using module bbclass This means that each built kernel module is packaged separately and inter module dependencies are created by parsing the modinfo output If all modules are required then installing the kerne
160. recipes as opposed to the thousands available in other OpenEmbedded community layers Keeping it small makes it easy to test and maintain The Yocto Project team runs manual and automated tests using a small fixed set of reference hardware as well as emulated targets The Yocto Project uses an an autobuilder which provides continuous build and integration tests How do get support for my board added to the Yocto Project Support for an additional board is added by creating a Board Support Package BSP layer for it For more information on how to create a BSP layer see the Understanding and Creating Layers http www yoctoproject org docs 1 4 2 dev manual dev manual html understanding and creating layers section in the Yocto Project Development Manual and the Yocto Project Board Support Package BSP Developer s Guide http www yoctoproject org docs 1 4 2 bsp guide bsp guide html Usually if the board is not completely exotic adding support in the Yocto Project is fairly straightforward Are there any products built using the OpenEmbedded build system The software running on the Vernier LabQuest http vernier com labquest is built using the OpenEmbedded build system See the Vernier LabQuest http www vernier com products 12 6 12 7 12 8 12 9 interfaces labq website for more information There are a number of pre production devices using the OpenEmbedded build system and the Yocto Project team announ
161. ribution machine and image features during the build process using the OpenEmbedded build system Variables Glossary Presents most variables used by the OpenEmbedded build system which uses BitBake Entries describe the function of the variable and how to apply them Variable Context Provides variable locality or context FAQ Provides answers for commonly asked questions in the Yocto Project development environment Contributing to the Yocto Project Provides guidance on how you can contribute back to the Yocto Project 1 3 System Requirements For general Yocto Project system requirements see the What You Need and How You Get It http www yoctoproject org docs 1 4 2 yocto project qs yocto project qs html yp resources section in the Yocto Project Quick Start The remainder of this section provides details on system requirements not covered in the Yocto Project Quick Start 1 3 1 Supported Linux Distributions Currently the Yocto Project is supported on the following distributions Ubuntu 10 04 Ubuntu 11 10 Ubuntu 12 04 LTS Ubuntu 12 10 Fedora release 16 Verne Fedora release 17 Beefy Miracle Fedora release 18 Spherical Cow CentOS release 5 6 Final CentOS release 5 7 Final CentOS release 5 8 Final CentOS release 6 3 Final CentOS release 6 4 Final Debian GNU Linux 6 0 squeeze Debian GNU Linux 7 0 openSUSE 11 4 openSUSE 12 1 openSUSE 12 2 openSUSE 12 3 Note
162. ripts is executed to run the main BitBake executable which resides in the bitbake bin directory Sourcing the oe init build env script places the scripts and bitbake bin directories in that order into the shell s PATH environment variable For more information on BitBake see the BitBake documentation included in the bitbake doc manual directory of the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory 5 1 2 build This directory contains user configuration files and the output generated by the OpenEmbedded build system in its standard configuration where the source tree is combined with the output The Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory is created initially when you source the OpenEmbedded build environment setup script oe init build env It is also possible to place output and configuration files in a directory separate from the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory by providing a directory name when you source the setup script For information on separating output from your local Source Directory files see the oe init build env section 5 1 3 documentation This directory holds the source for the Yocto Project documentation as well as templates and tools that allow you to generate PDF and HTML versions of the manuals Each manual is contained in a su
163. rride This variable is used in recipes when using update rc d bbclass The variable is optional and defaults to the PN variable The filename of the initscript as installed to etcdir init d This variable is used in recipes when using update rc d bbclass The variable is Mandatory Specifies the options to pass to update rc d Here is an example INITSCRIPT PARAMS start 99 5 2 stop 20016 In this example the script has a runlevel of 99 starts the script in initlevels 2 and 5 and stops the script in levels 0 1 and 6 The variable is mandatory and is used in recipes when using update rc d bbclass Specifies the QA checks to skip for a specific package within a recipe For example to skip the check for symbolic link so files in the main package of a recipe add the following to the recipe The package name override must be used which in this example is PN INSANE SKIP PN dev so See the Generated Output Quality Assurance Checks insane bbclass section for a list of the valid QA checks you can specify using this variable Defines the kernel architecture used when assembling the configuration Architectures supported for this release are powerpc arm 1386 mips powerpc x86_64 You define the KARCH variable in the BSP Descriptions http www yoctoproject org docs 1 4 2 kernel dev kernel dev html bsp descriptions KBRANCH A regular expression used by the build process to explicitly identify t
164. rs BitBake tries to find The file uses the BBLAYERS_NON_REMOVABLE variable to list layers that must not be removed 5 2 4 build conf sanity_info This file indicates the state of the sanity checks and is created during the build 5 2 5 build downloads This directory contains downloaded upstream source tarballs You can reuse the directory for multiple builds or move the directory to another location You can control the location of this directory through the DL_DIR variable 5 2 6 build sstate cache This directory contains the shared state cache You can reuse the directory for multiple builds or move the directory to another location You can control the location of this directory through the SSTATE_DIR variable 5 2 7 build tmp This directory receives all the OpenEmbedded build system s output BitBake creates this directory if it does not exist As a last resort to clean up a build and start it from scratch other than the downloads you can remove everything in the tmp directory or get rid of the directory completely If you do you should also completely remove the build sstate cache directory 5 2 8 build tmp buildstats This directory stores the build statistics 5 2 9 build tmp cache When BitBake parses the metadata it creates a cache file of the result that can be used when subsequently running commands BitBake stores these results here on a per machine basis 5 2 10 build tmp deploy This directory co
165. rtrail cedartrail KBRANCH cedartrail yocto standard cedartrail KERNEL FEATURES append cedartrail bsp cedartrail cedartrail p KERNEL_FEATURES_append_cedartrail cfg efi ext scc COMPATIBLE MACHINE cedartrail nopvr cedartrail KMACHINE cedartrail nopvr cedartrail KBRANCH cedartrail nopvr yocto standard cedartrail KERNEL FEATURES append cedartrail nopvr cfg smp scc The KMACHINE statements in the kernel s append file make sure that the OpenEmbedded build system and the Yocto Linux kernel understand the same machine names This append file uses two KMACHINE statements The first is not really necessary but does ensure that the machine known to the OpenEmbedded build system as cedartrail maps to the machine in the kernel also known as cedartrail KMACHINE cedartrail cedartrail The second statement is a good example of why the KMACHINE variable is needed In this example the OpenEmbedded build system uses the cedartrail nopvr machine name to refer to the Cedar Trail BSP that does not support the proprietary PowerVR driver The kernel however uses the machine name cedartrail Thus the append file must map the cedartrail nopvr machine name to the kernel s cedartrail name KMACHINE cedartrail nopvr cedartrail BSPs that ship with the Yocto Project release provide all mappings between the Yocto Project kernel machine names and the OpenEmbedded machine names Be sure to use the KMACHINE if you create a
166. ry packages core2 poky linux busybox latest PV PR 1 19 3 r3 DEPENDS virtual i586 poky linux gcc virtual i586 poky linux compilerlibs virtual libc update rc d native PACKAGES busybox httpd busybox udhcpd busybox udhcpc busybox syslog busybox mdev busybox dbg busybox busybox doc busybox dev busybox staticdev busybox locale Finally for those recipes fetched from a version control system e g Git a file exists that lists source revisions that are specified in the recipe and lists the actual revisions used during the build Listed and actual revisions might differ when SRCREV is set to AUTOREV Here is an example assuming buildhistory packages emenlow poky linux linux yocto latest srcrev SRCREV machine b5c37fe6e24eec194bb29d22fdd55d73bcc709bf SRCREV machine b5c37fe6e24eec194bb29d22fdd55d73bcc709bf SRCREV emgd caea08c988e0f41103bbe18eafca20348f95da02 SRCREV emgd caea08c988e0f41103bbe18eafca20348f95da02 SRCREV meta c2ed0f16fdec628242a682897d5d86df4547cf24 SRCREV meta c2ed0f16fdec628242a682897d5d86df4547cf24 You can use the buildhistory collect srcrevs command to collect the stored SRCREV values from build history and report them in a format suitable for use in global configuration e g local conf or a distro include file to override floating AUTOREV values to a fixed set of revisions Here is some example output from this command emenlow poky linux SRCREV machine pn linux yocto
167. s 39 5 3 21 metaZSTt67 x eine eines dex e edie GPa e erede eee 39 5 3 22 meta re ctpes EXE caido uei dee UH ie ti E Eu 39 6 BIEBak 5 a A pes pecan E bo certe e ERU DE Dr URP U De 40 Oi A i e ape i ie e tees ee ede eee oet pode tees Dp d o ed a eodera 40 6 2 Preferences and Providers ssssssssssrsssrsrssrtttttretttttttt srt Su mene ene hn rennen nennen nnns 40 6 3 Depende 41 6 4 The TASK LISS catre ada 41 6 5 Running a Task eas ter e qo ee QUEE RDUM Hoi ENDO I QR ERE Lo pesi HAC cud 42 6 62 BitBake Command Line iia A A a E ein 42 a rd PEE 43 CASOS MC EC EccL 44 7 1 The base Class base bbclass sssssssssssssememm meme nenne rnnt rennes 44 7 2 Autotooled Packages autotools bbclass ssssssseee eee 44 7 3 Alternatives update alternatives bbclass 00 cece eect eee mme 44 7 4 Initscripts update rc d bbclass oo mme rne 45 7 5 Binary Configuration Scripts binconfig bbclass ssssseee e 45 7 6 Debian Renaming debian bbclass ssssssssmemm eene rennen 45 7 7 Pkg config pkgconfig bbclass 0 el mee nennen rennen nennen 45 7 8 Archiving Sources archive bbclass ssssssssssn meme mener 45 7 9 Perl Modules cpan bbclass 00 menm nnne rne nnne nnns 45 7 10 Python Extensions distutils bbclass sssssse mme 46 7 11 Developer Shell devshell bbclass oo nee ee reer mee eere 46 7 12 Package Groups packagegroup bbclass
168. s common prefixes such as multilib s lib64 and lib32 The exact list of suffixes removed is specified by the SPECIAL PKGSUFFIX variable The exact list of prefixes removed is specified by the MLPREFIX variable Prefixes are removed for multilib and nativesdk cases Points to the location of the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory You can define this directory indirectly through the oe init build env script by passing in a Build Directory path when you run the script If you run the script and do not provide a Build Directory path the BUILDDIR defaults to build in the current directory Flags passed to the C compiler for the target system This variable evaluates to the same as TARGET CFLAGS A set of features common between MACHINE FEATURES and DISTRO FEATURES See the glossary descriptions for these variables for more information A regular expression that resolves to one or more hosts when the recipe is native or one or more targets when the recipe is non native with which a recipe is compatible The regular expression is matched against HOST SYS You can use the variable to stop recipes from being built for classes of systems with which the recipes are not compatible Stopping these builds is particularly useful with kernels The variable also helps to increase parsing speed since the build system skips parsing recipes not compatible with the current system A r
169. s such as oprofile exmap and LTTng For general information on user space tools see the User Space Tools http www yoctoproject org docs 1 4 2 adt manual adt manual html user space tools section in the Yocto Project Application Developer s Guide tools sdk Installs a full SDK that runs on the device tools testapps Installs device testing tools e g touchscreen debugging X11 Installs the X server x11 base Installs the X server with a minimal environment e x11 sato Installs the OpenedHand Sato environment 9 4 Feature Backfilling Sometimes it is necessary in the OpenEmbedded build system to extend MACHINE FEATURES or DISTRO_FEATURES to control functionality that was previously enabled and not able to be disabled For these cases we need to add an additional feature item to appear in one of these variables but we do not want to force developers who have existing values of the variables in their configuration to add the new feature in order to retain the same overall level of functionality Thus the OpenEmbedded build system has a mechanism to automatically backfill these added features into existing distro or machine configurations You can see the list of features for which this is done by finding the DISTRO FEATURES BACKFILL and MACHINE FEATURES BACKFILL variables in the meta conf bitbake conf file Because such features are backfilled by default into all configurations as described in the previous paragraph deve
170. specified by DEPENDS Note A recipe s own PN is implicitly already in its PROVIDES list PV The version of the recipe The version is normally extracted from the recipe filename For example if the recipe is named expat 2 0 1 bb then the default value of PV will be 2 0 1 PV is generally not overridden within a recipe unless it is building an unstable i e development version from a source code repository e g Git or Subversion PE the epoch of the recipe The default value is 0 The field is used to make upgrades possible when the versioning scheme changes in some backwards incompatible way PREFERRED PROVIDER If multiple recipes provide an item this variable determines which recipe should be given preference You should always suffix the variable with the name of the provided item and you should set it to the PN of the recipe to which you want to give precedence Here is an example PREFERRED PROVIDER virtual xserver xserver xf86 PREFERRED_VERSION If there are multiple versions of recipes available this variable determines which recipe should be given preference You must always suffix the variable with the PN you want to select and you should set to the PV accordingly for precedence You can use the character as a wildcard to match any number of characters which can be useful when specifying versions that contain long revision number that could potentially change Here are two examples PREFERRED VERSION py
171. t build env setup script By default this Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory is named build but can be named anything you want Within the Build Directory is the tmp directory To remove all the build output yet preserve any Source code or downloaded files from previous builds simply remove the tmp directory Chapter 13 Contributing to the Yocto Project 13 1 Introduction The Yocto Project team is happy for people to experiment with the Yocto Project A number of places exist to find help if you run into difficulties or find bugs To find out how to download source code see the Yocto Project Release http www yoctoproject org docs 1 4 2 dev manual dev manual html local yp release section in the Yocto Project Development Manual 13 2 Tracking Bugs If you find problems with the Yocto Project you should report them using the Bugzilla application at http bugzilla yoctoproject org 13 3 Mailing lists A number of mailing lists maintained by the Yocto Project exist as well as related OpenEmbedded mailing lists for discussion patch submission and announcements To subscribe to one of the following mailing lists click on the appropriate URL in the following list and follow the instructions http lists yoctoproject org listinfo yocto General Yocto Project discussion mailing list http lists linuxtogo org cgi bin mailman listinfo openembedded core Discussio
172. tches or files that reside with your append files you need to extend the FILESPATH variable by using the FILESEXTRAPATHS variable FILESYSTEM PERMS TABLES X Allows you to define your own file permissions settings table as part of your configuration for the packaging process For example suppose you need a consistent set of custom permissions for a set of groups and users across an entire work project It is best to do this in the packages themselves but this is not always possible By default the OpenEmbedded build system uses the fs perms txt which is located in the meta files folder in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory If you create your own file permissions setting table you should place it in your layer or the distros layer You define the FILESYSTEM PERMS TABLES variable in the conf local conf file which is found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory to point to your custom fs perms txt You can specify more than a single file permissions setting table The paths you specify to these files must be defined within the BBPATH variable For guidance on how to create your own file permissions settings table file examine the existing fs perms txt FULL OPTIMIZATION The options to pass in TARGET CFLAGS and CFLAGS when compiling an optimized system This variable defaults to fexpensive opti
173. text file containing name value pairs with information about the image See the following listing example for more information installed package names txt A list of installed packages by name only installed package sizes txt A list of installed packages ordered by size installed packages txt A list of installed packages with full package filenames Note Installed package information is able to be gathered and produced even if package management is disabled for the final image Here is an example of image info txt DISTRO poky DISTRO VERSION 1 1 snapshot 20120207 USER_CLASSES image mklibs image prelink IMAGE CLASSES image types IMAGE FEATURES debug tweaks x11 base apps x11 core Y package management ssh server dropbear package management IMAGE LINGUAS en us en gb IMAGE INSTALL task core boot task base extended BAD RECOMMENDATIONS ROOTFS POSTPROCESS COMMAND buildhistory get image installed rootfs update timestamp IMAGE POSTPROCESS COMMAND buildhistory get imageinfo IMAGESIZE 171816 Other than IMAGESIZE which is the total size of the files in the image in Kbytes the name value pairs are variables that may have influenced the content of the image This information is often useful when you are trying to determine why a change in the package or file listings has occurred 2 4 2 3 Using Build History to Gather Image Information Only As you can see build history produces image information
174. the XPrint server was removed from Xorg in 2008 libxtrap xtrapproto Removed because their functionality was broken upstream linux yocto 3 0 kernel Removed with linux yocto 3 8 kernel being added The linux yocto 3 2 and linux yocto 3 4 kernels remain as part of the release lsbsetup Removed with functionality now provided by lsbtest matchbox stroke Removed because it was never more than a proof of concept matchbox wm 2 matchbox theme sato 2 Removed because they are not maintained However matchbox wm and matchbox theme sato are still provided mesa dri Renamed to mesa mesa xlib Removed because it was no longer useful mutter Removed because nothing ever uses it and the recipe is very old orinoco conf Removed because it has become obsolete update modules Removed because it is no longer used The kernel module postinstall and postrm scripts can now do the same task without the use of this script web Removed because it is not maintained Superseded by web webkit xf86bigfontproto Removed because upstream it has been disabled by default since 2007 Nothing uses xf86bigfontproto xf86rushproto Removed because its dependency in xserver was spurious and it was removed in 2005 zypper libzypp sat solver Removed and been functionally replaced with Smart python smartpm when RPM packaging is used and package management is enabled on the target Chapter 5 Source Directory Structure The Source Directory
175. the comments of one of the functions it calls The change is purely cosmetic but it causes the checksum to be recalculated and forces the task to be run again Note For an example of a commit that makes a cosmetic change to invalidate a shared state see this commit http git yoctoproject org cgit cgi poky commit meta classes package bbclass id 737f8bbb4f27b4837047cb9b4fbfe01dfde36d541 3 3 X32 x32 is a processor specific Application Binary Interface psABI for x86_64 An ABI defines the calling conventions between functions in a processing environment The interface determines what registers are used and what the sizes are for various C data types Some processing environments prefer using 32 bit applications even when running on Intel 64 bit platforms Consider the i386 psABI which is a very old 32 bit ABI for Intel 64 bit platforms The i386 psABI does not provide efficient use and access of the Intel 64 bit processor resources leaving the system underutilized Now consider the x86_64 psABI This ABI is newer and uses 64 bits for data sizes and program pointers The extra bits increase the footprint size of the programs libraries and also increases the memory and file system size requirements Executing under the x32 psABI enables user programs to utilize CPU and system resources more efficiently while keeping the memory footprint of the applications low Extra bits are used for registers but not for addressing mechanisms 3 3 1 S
176. thon 2 6 6 PREFERRED VERSION linux yocto 3 0 git R RCONFLICTS The list of packages that conflict with another package Note that the package will not be installed if the conflicting packages are not first removed Like all package controlling variables you must always use them in conjunction with a package name override Here is an example RCONFLICTS PN another conflicting package name RDEPENDS Lists a package s run time dependencies i e other packages that must be installed in order for the built package to run correctly If a package in this list cannot be found during the build you will get a build error The names of the packages you list within RDEPENDS must be the names of other packages they cannot be recipe names Although package names and recipe names usually match the important point here is that you are providing package names within the RDEPENDS variable For an example of the default list of packages created from a recipe see the PACKAGES variable Because the RDEPENDS variable applies to packages being built you should always use the variable in a form with an attached package name For example suppose you are building a development package that depends on the perl package In this case you would use the following RDEPENDS statement RDEPENDS PN dev perl In the example the development package depends on the perl package Thus the RDEPENDS variable has the PN dev package name
177. tion However to skip one or more checks in recipes you should use INSANE SKIP For example to skip the check for symbolic link so files in the main package of a recipe add the following to the recipe You need to realize that the package name override in this example PN must be used INSANE SKIP PN dev so Please keep in mind that the QA checks exist in order to detect real or potential problems in the packaged output So exercise caution when disabling these checks 7 18 Removing Work Files During the Build rm work bbclass The OpenEmbedded build system can use a substantial amount of disk space during the build process A portion of this space is the work files under the TMPDIR work directory for each recipe Once the build system generates the packages for a recipe the work files for that recipe are no longer needed However by default the build system preserves these files for inspection and possible debugging purposes If you would rather have these files deleted to save disk space as the build progresses you can enable rm work by adding the following to your local conf file which is found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory INHERIT rm work If you are modifying and building source code out of the work directory for a recipe enabling rm work will potentially result in your changes to the source being lost To exclude some recipes from ha
178. to build different variants of a recipe you can use the BBCLASSEXTEND variable When you do the B variable must support the recipe s ability to build variants in different working directories Most Autotools based recipes support separating these directories The OpenEmbedded build system defaults to using separate directories for gcc and some kernel recipes Alternatively you can make sure that separate recipes exist that each use the BBCLASSEXTEND variable to build each variant The separate recipes can inherit a single target recipe For information on how to use this class see the Building Software from an External Source http www yoctoproject org docs 1 4 2 dev manual dev manual html building software from an external source section in the Yocto Project Development Manual 7 22 Other Classes Thus far this chapter has discussed only the most useful and important classes However other classes exist within the meta classes directory in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory You can examine the bbclass files directly for more information Chapter 8 Images The OpenEmbedded build process supports several types of images to satisfy different needs When you issue the bitbake command you provide a top level recipe that essentially begins the build for the type of image you want Note Building an image without GNU General Public License Version 3 GPLv3
179. tp www yoctoproject org docs 1 4 2 dev manual dev manual html source directory When defining the variable you can specify one or more package types Since images are generated from packages a packaging class is needed to enable image generation The first class listed in this variable is used for image generation If you take the optional step to set up a repository package feed on the development host that can be used by Smart you can install packages from the feed while you are running the image on the target i e runtime installation of packages For information on how to set up this repository see the Setting Up Runtime Package Management http www yoctoproject org docs 1 4 2 dev manual dev manual html setting up runtime package management in the Yocto Project Development Manual The package class you choose can affect build time performance and has space ramifications In general building a package with IPK takes about thirty percent less time as compared to using RPM to build the same or similar package This comparison takes into account a complete build of the package with all dependencies previously built The reason for this discrepancy is because the RPM package manager creates and processes more Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata than the IPK package manager Consequently you might consider setting PACKAGE CLASSES to package_ipk if you are building smaller systems Befo
180. tring as the first portion of its license For example the following whitelist string will also match both of the packages previously mentioned as well as any other packages that have licenses starting with commercial or license LICENSE FLAGS WHITELIST commercial license 3 5 2 1 License Flag Matching License flag matching allows you to control what recipes the OpenEmbedded build system includes in the build Fundamentally the build system attempts to match LICENSE FLAG strings found in recipes against LICENSE FLAGS WHITELIST strings found in the whitelist A match causes the build system to include a recipe in the build while failure to find a match causes the build system to exclude a recipe In general license flag matching is simple However understanding some concepts will help you correctly and effectively use matching Before a flag defined by a particular recipe is tested against the contents of the whitelist the expanded string _ PN is appended to the flag This expansion makes each LICENSE FLAGS value recipe specific After expansion the string is then matched against the whitelist Thus specifying LICENSE FLAGS commercial in recipe foo for example results in the string commercial foo And to create a match that string must appear in the whitelist Judicious use of the LICENSE FLAGS strings and the contents of the LICENSE FLAGS WHITELIST variable allows you a lot of flexibility for including or excluding r
181. u to extend a recipe so that it builds variants ofthe software Common variants for recipes exist such as natives like quilt native which is a copy of Quilt built to run on the build system crosses such as gcc cross which is a compiler built to run on the build machine but produces binaries that run on the target MACHINE nativesdk which targets the SDK machine instead of MACHINE and mulitlibs in the form multilib lt multilib name gt To build a different variant of the recipe with a minimal amount of code it usually is as simple as adding the following to your recipe BBCLASSEXTEND native nativesdk BBCLASSEXTEND multilib lt multilib_name gt BBMASK Prevents BitBake from processing recipes and recipe append files Use the BBMASK variable from within the conf local conf file found in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory You can use the BBMASK variable to hide these bb and bbappend files BitBake ignores any recipe or recipe append files that match the expression It is as if BitBake does not see them at all Consequently matching files are not parsed or otherwise used by BitBake The value you provide is passed to Python s regular expression compiler The expression is compared against the full paths to the files For complete syntax information see Python s documentation at http docs python org release 2 3 lib re syntax html The foll
182. ul if you want to ensure code builds only from local sources Here is another technique BB FETCH PREMIRRORONLY 1 This statement limits the build system to pulling source from the PREMIRRORS only Again this technique is useful for reproducing builds Here is another technique BB GENERATE MIRROR TARBALLS 1 This statement tells the build system to generate mirror tarballs This technique is useful if you want to create a mirror server If not however the technique can simply waste time during the build Finally consider an example where you are behind an HTTP only firewall You could make the following changes to the local conf configuration file as long as the PREMIRRORS server is current PREMIRRORS prepend N ftp http www yoctoproject org sources An http http www yoctoproject org sources An https http ww yoctoproject org sources Xn BB FETCH PREMIRRORONLY 1 These changes would cause the build system to successfully fetch source over HTTP and any network accesses to anything other than the PREMIRRORS would fail The build system also honors the standard shell environment variables http_proxy ftp proxy https proxy and all proxy to redirect requests through proxy servers 12 24Can get rid of build output so can start over Yes you can easily do this When you use BitBake to build an image all the build output goes into the directory created when you source the oe ini
183. untime package management is enabled and the RPM backend is selected Smart is now installed for package download dependency resolution and upgrades instead of Zypper For more information on how to use Smart run the following command on the target smart help 4 2 8 Recipes Moved The following recipes were moved from their previous locations because they are no longer used by anything in the OpenEmbedded Core clutter box2d Now resides in the meta oe layer evolution data server Now resides in the meta gnome layer gthumb Now resides in the meta gnome layer gtkhtml2 Now resides in the meta oe layer gupnp Now resides in the meta multimedia layer gypsy Now resides in the meta oe layer libcanberra Now resides in the meta gnome layer libgdata Now resides in the meta gnome layer libmusicbrainz Now resides in the meta multimedia layer metacity Now resides in the meta gnome layer polkit Now resides in the meta oe layer zeroconf Now resides in the meta networking layer 4 2 9 Removals and Renames The following list shows what has been removed or renamed evieext Removed because it has been removed from xserver since 2008 Gtk DirectFB Removed support because upstream Gtk no longer supports it as of version 2 18 libxfontcache xfontcacheproto Removed because they were removed from the Xorg server in 2008 libxp libxprintapputil libxprintutil printproto Removed because
184. upport While the x32 psABI specifications are not fully finalized this Yocto Project release supports current development specifications of x32 psABI As of this release of the Yocto Project x32 psABI support exists as follows You can create packages and images in x32 psABI format on x86 64 architecture targets You can successfully build many recipes with the x32 toolchain You can create and boot core image minimal and core image sato images 3 3 2 Stabilizing and Completing x32 As of this Yocto Project release the x32 psABI kernel and library interfaces specifications are not finalized Future Plans for the x32 psABI in the Yocto Project include the following Enhance and fix the few remaining recipes so they work with and support x32 toolchains Enhance RPM Package Manager RPM support for x32 binaries Support larger images 3 3 3 Using x32 Right Now Follow these steps to use the x32 spABI Enable the x32 psABI tuning file for x86 64 machines by editing the conf local conf like this MACHINE qemux86 64 DEFAULTTUNE x86 64 x32 baselib d getVar BASE LIB tune d getVar DEFAULTTUNE True or INVALID True or lib MACHINE atom pc DEFAULTTUNE core2 64 x32 As usual use BitBake to build an image that supports the x32 psABI Here is an example bitbake core image sato As usual run your image using QEMU runqemu qemux86 64 core image sato 3 4 Wayland
185. uring runtime Distribution policy usually dictates whether to include this class You can configure the sanity checks so that specific test failures either raise a warning or an error message Typically failures for new tests generate a warning Subsequent failures for the same test would then generate an error message once the metadata is in a known and good condition You use the WARN QA variable to specify tests for which you want to generate a warning message on failure You use the ERROR_QA variable to specify tests for which you want to generate an error message on failure The following list shows the tests you can list with the WARN_QA and ERROR_QA variables ldflags Ensures that the binaries were linked with the LDFLAGS options provided by the build system If this test fails check that the LDFLAGS variable is being passed to the linker command useless rpaths Checks for dynamic library load paths rpaths in the binaries that by default on a standard system are searched by the linker e g Lib and usr lib While these paths will not cause any breakage they do waste space and are unnecessary rpaths Checks for rpaths in the binaries that contain build system paths such as TMPDIR If this test fails bad rpath options are being passed to the linker commands and your binaries have potential security issues dev so Checks that the so symbolic links are in the dev package and not in any of the other packages In general thes
186. used There are other directories generated within WORKDIR The most important directory is WORKDIR temp which has log files for each task log do pid and contains the scripts BitBake runs for each task run do pid The WORKDIR image directory is where make install places its output that is then split into sub packages within WORKDIR packages split 5 3 The Metadata meta As mentioned previously Metadata http www yoctoproject org docs 1 4 2 dev manual dev manual html metadata is the core of the Yocto Project Metadata has several important subdivisions 5 3 1 meta classes This directory contains the bbclass files Class files are used to abstract common code so it can be reused by multiple packages Every package inherits the base bbclass file Examples of other important classes are autotools bbclass which in theory allows any Autotool enabled package to work with the Yocto Project with minimal effort Another example is kernel bbclass that contains common code and functions for working with the Linux kernel Functions like image generation or packaging also have their specific class files such as image bbclass rootfs bbclass and package bbclass For reference information on classes see the Classes chapter 5 3 2 meta conf This directory contains the core set of configuration files that start from bitbake conf and from which all other configuration files are included See the include statements at the end
187. version string of the current package This string is used to help define the value of PV The SRCPV variable is defined in the meta conf bitbake conf configuration file in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory as follows SRCPV bb fetch2 get_srcrev d Recipes that need to define PV do so with the help of the SRCPV For example the ofono recipe ofono git bb located in meta recipes connectivity in the Source Directory defines PV as follows PV 1 5 0 git SRCPV The revision of the source code used to build the package This variable applies to Subversion Git Mercurial and Bazaar only Note that if you wish to build a fixed revision and you wish to avoid performing a query on the remote repository every time BitBake parses your recipe you should specify a SRCREV that is a full revision identifier and not just a tag The directory for the shared state cache Configures the OpenEmbedded build system to search other mirror locations for prebuilt cache data objects before building out the data This variable works like fetcher MIRRORS and PREMIRRORS and points to the cache locations to check for the shared objects You can specify a filesystem directory or a remote URL such as HTTP or FTP The locations you specify need to contain the shared state cache sstate cache results from previous builds The sstate cache you point to can also be from builds on
188. ving their work directories deleted by rm work you can add the names of the recipe or recipes you are working on to the RM WORK EXCLUDE variable which can also be set in your local conf file Here is an example RM WORK EXCLUDE busybox eglibc 7 19 Autotools Configuration Data Cache siteinfo bbclass Autotools can require tests that must execute on the target hardware Since this is not possible in general when cross compiling site information is used to provide cached test results so these tests can be skipped over but still make the correct values available The meta site directory contains test results sorted into different categories such as architecture endianness and the libc used Site information provides a list of files containing data relevant to the current build in the CONFIG_SITE variable that Autotools automatically picks up The class also provides variables like SITEINFO ENDIANNESS and SITEINFO BITS that can be used elsewhere in the metadata Because this class is included from base bbclass it is always active 7 20 Adding Users useradd bbclass If you have packages that install files that are owned by custom users or groups you can use this class to specify those packages and associate the users and groups with those packages The meta skeleton recipes skeleton useradd useradd example bb recipe in the Source Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html source directory provides a
189. way the build system obtains source code is highly configurable You can setup the build system to get source code in most environments if HTTP transport is available When the build system searches for source code it first tries the local download directory If that location fails Poky tries PREMIRRORS the upstream source and then MIRRORS in that order Assuming your distribution is poky the OpenEmbedded build system uses the Yocto Project source PREMIRRORS by default for SCM based sources upstreams for normal tarballs and then falls back to a number of other mirrors including the Yocto Project source mirror if those fail As an example you could add a specific server for the build system to attempt before any others by adding something like the following to the Local conf configuration file PREMIRRORS prepend git http www yoctoproject org sources An ftp http www yoctoproject org sources An http http www yoctoproject org sources An https http www yoctoproject org sources Xn These changes cause the build system to intercept Git FTP HTTP and HTTPS requests and direct them to the http sources mirror You can use file URLs to point to local directories or network shares as well Aside from the previous technique these options also exist BB NO NETWORK 1 This statement tells BitBake to issue an error instead of trying to access the Internet This technique is usef
190. widget abi 2 A list of packages that extends the usability of a package being built The package being built does not depend on this list of packages in order to successfully build but needs them for the extended usability To specify runtime dependencies for packages see the RDEPENDS variable The OpenEmbedded build process automatically installs the list of packages as part of the built package However you can remove them later if you want If during the build a package from the list cannot be found the build process continues without an error Because the RRECOMMENDS variable applies to packages being built you should always attach an override to the variable to specify the particular package whose usability is being extended For example suppose you are building a development package that is extended to support wireless functionality In this case you would use the following RRECOMMENDS PN dev lt wireless package name gt In the example the package name PN dev must appear as it would in the PACKAGES namespace before any renaming of the output package by classes like debian bbclass A list of packages replaced by a package The package manager uses this variable to determine which package should be installed to replace other package s during an upgrade In order to also have the other package s removed at the same time you must add the name of the other package to the RCONFLICTS variable As with all pack
191. www yoctoproject org docs 1 4 2 dev manual dev manual html build directory The OpenEmbedded build system places generated objects into the Build Directory during a recipe s build process By default this directory is the same as the S directory B WORKDIR BPN PV You can separate the S directory and the directory pointed to by the B variable Most Autotools based recipes support separating these directories The build system defaults to using separate directories for gcc and some kernel recipes A list of packages not to install despite being recommended by a recipe Support for this variable exists only when using the IPK packaging backend BB_DANGLINGAPPENDS_WARNODkf nes how BitBake handles situations where an append file bbappend has no corresponding recipe file bb This condition often occurs when layers get out of sync e g oe core bumps a recipe version and the old recipe no longer exists and the other layer has not been updated to the new version of the recipe yet The default fatal behavior is safest because it is the sane reaction given something is out of sync It is important to realize when your changes are no longer being applied BB_DISKMON_DIRS You can change the default behavior by setting this variable to 1 in the local conf file in the Build Directory http www yoctoproject org docs 1 4 2 dev manual dev manual html build directory as follows BB DANGLINGAPPENDS WARNONLY 1 Mon
192. xtracted Since the sysroot is not used it would never get extracted This is another reason why a task based approach is preferred over a recipe based approach which would have to install the output from every task 3 2 4 Tips and Tricks The code in the build system that supports incremental builds is not simple code This section presents some tips and tricks that help you work around issues related to shared state code 3 2 4 1 Debugging When things go wrong debugging needs to be straightforward Because of this the Yocto Project team included strong debugging tools Whenever a shared state package is written out so is a corresponding siginfo file This practice results in a pickled Python database of all the metadata that went into creating the hash for a given shared state package If you run BitBake with the dump signatures or S option BitBake dumps out siginfo files in the stamp directory for every task it would have executed instead of building the specified target package There is a bitbake diffsigs command that can process siginfo files If you specify one of these files BitBake dumps out the dependency information in the file If you specify two files BitBake compares the two files and dumps out the differences between the two This more easily helps answer the question of What changed between X and Y 3 2 4 2 Invalidating Shared State The shared state code uses checksums and shared state cache to av
193. yer e g BBFILE PATTERN emenlow Assigns the priority for recipe files in each layer This variable is useful in situations where the same recipe appears in more than one layer Setting this variable allows you to prioritize a layer against other layers that contain the same recipe effectively letting you control the precedence for the multiple layers The precedence established through this variable stands regardless of a recipe s version PV variable For example a layer that has a recipe with a higher PV value but for which the BBFILE PRIORITY is set to have a lower precedence still has a lower precedence A larger value for the BBFILE PRIORITY variable results in a higher precedence For example the value 6 has a higher precedence than the value 5 If not specified the BBFILE PRIORITY variable is set based on layer dependencies see the LAYERDEPENDS variable for more information The default priority if unspecified for a layer with no dependencies is the lowest defined priority 1 or 1 if no priorities are defined Tip You can use the command bitbake layers show layers to list all configured layers along with their priorities List of recipe files used by BitBake to build software Used by BitBake to locate bbclass and configuration files This variable is analogous to the PATH variable Variable that controls how BitBake displays logs on build failure Lists the layers to enable during the build This variable is de
194. yocto Yocto Project mee Reference Manual Richard Purdie Linux Foundation richard purdieglinuxfoundation org by Richard Purdie Copyright O 2010 2013 Linux Foundation Permission is granted to copy distribute and or modify this document under the terms of the Creative Commons Attribution Share Alike 2 0 UK England amp Wales http creativecommons org licenses by sa 2 0 uk as published by Creative Commons Note Due to production processes there could be differences between the Yocto Project documentation bundled in the release tarball and the Yocto Project Reference Manual http www yoctoproject org docs 1 4 2 ref manual ref manual html on the Yocto Project http www yoctoproject org website For the latest version of this manual see the manual on the website Table of Contents 1 Intr dUctiOD turo A O Ue Ie ES 1 1 1 IntrodUctlOl inh Ec ett e eh Ar ege Eo ceret etta 1 1 2 Documentation Overview ssssessssssseeeeneene NE men nen nne tese tenete nne nennen 1 1 3 System Requirements oca toL ace dies es EDU ee E bte Pe cedar eot tps 1 1 3 1 Supported Linux Distributions sssssssssnme enne hene 1 1 3 2 Required Packages for the Host Development System oocccoccnnccnnccnncconinaninaninnnos 2 1 4 Obtaining the Yocto Project occoncconcconccocncocnnornnnrnnnnnnnnrnnncnnncnnnnnernnrrnnnrnnnrnrnnnrrenrrnnrinnnes 4 1 5 Development Checkouts 00 00 ccc cence eee ee eee reer area nenn

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