From d1fe084c030d120dc3d1715f00b91022676366df Mon Sep 17 00:00:00 2001 From: Scott Rifenbark Date: Tue, 9 Oct 2012 11:38:35 -0700 Subject: documentation: dev-manual - edits to patching kernel section plus others Removed the temporary text in the new "Patching the Kernel" section that was copied from the old appendix A. Fixed the PRINC variable in the creating a new layer example. (From yocto-docs rev: 3eba77a81d3460866638a2f2d6b7c27d9dd1a2be) Signed-off-by: Scott Rifenbark Signed-off-by: Richard Purdie --- .../dev-manual/dev-manual-common-tasks.xml | 322 +-------------------- 1 file changed, 8 insertions(+), 314 deletions(-) (limited to 'documentation/dev-manual') diff --git a/documentation/dev-manual/dev-manual-common-tasks.xml b/documentation/dev-manual/dev-manual-common-tasks.xml index 48d86fac25..78c1f39e18 100644 --- a/documentation/dev-manual/dev-manual-common-tasks.xml +++ b/documentation/dev-manual/dev-manual-common-tasks.xml @@ -315,7 +315,7 @@ FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" - PRINC = "1" + PRINC := "${@int(PRINC) + 1}" This example adds or overrides files in SRC_URI @@ -1605,7 +1605,7 @@ Patching the Kernel - Kernel modification involves changing or adding configurations to an existing kernel, + Patching the kernel involves changing or adding configurations to an existing kernel, changing or adding recipes to the kernel that are needed to support specific hardware features, or even altering the source code itself. @@ -1618,15 +1618,15 @@ - This example adds some simple QEMU emulator console output at boot time by - adding printk statements to the kernel's + This example creates a simple patch by adding some QEMU emulator console + output at boot time through printk statements in the kernel's calibrate.c source code file. - Booting the modified image causes the added messages to appear on the emulator's - console. + Applying the patch and booting the modified image causes the added + messages to appear on the emulator's console. -
- Finding the Kernel Source Files +
+ Creating the Patch Describe how to find the source files in the build area. @@ -1635,305 +1635,6 @@
-
- Understanding the Files You Need - - - Before you modify the kernel, you need to know what Git repositories and file - structures you need. - Briefly, you need the following: - - A local - Source Directory for the - poky Git repository - Local copies of the - poky-extras - Git repository placed within the Source Directory. - A bare clone of the - Yocto Project Kernel upstream Git - repository to which you want to push your modifications. - - A copy of that bare clone in which you make your source - modifications - - - - - The following figure summarizes these four areas. - Within each rectangular that represents a data structure, a - host development directory pathname appears at the - lower left-hand corner of the box. - These pathnames are the locations used in this example. - The figure also provides key statements and commands used during the kernel - modification process: - - - - - - - - Here is a brief description of the four areas: - - Local Source Directory: - This area contains all the metadata that supports building images - using the OpenEmbedded build system. - In this example, the - Source Directory also - contains the - Build Directory, - which contains the configuration directory - that lets you control the build. - Also in this example, the Source Directory contains local copies of the - poky-extras Git repository. - See the bulleted item - "Yocto Project Release" - for information on how to get these files on your local system. - Local copies of the poky-extras Git Repository: - This area contains the meta-kernel-dev layer, - which is where you make changes that append the kernel build recipes. - You edit .bbappend files to locate your - local kernel source files and to identify the kernel being built. - This Git repository is a gathering place for extensions to the Yocto Project - (or really any) kernel recipes that faciliate the creation and development - of kernel features, BSPs or configurations. - See the bulleted item - "The - poky-extras Git Repository" - for information on how to get these files. - Bare Clone of the Yocto Project kernel: - This bare Git repository tracks the upstream Git repository of the Linux - Yocto kernel source code you are changing. - When you modify the kernel you must work through a bare clone. - All source code changes you make to the kernel must be committed and - pushed to the bare clone using Git commands. - As mentioned, the .bbappend file in the - poky-extras repository points to the bare clone - so that the build process can locate the locally changed source files. - See the bulleted item - "Yocto Project Kernel" - for information on how to set up the bare clone. - - Copy of the Yocto Project Kernel Bare Clone: - This Git repository contains the actual source files that you modify. - Any changes you make to files in this location need to ultimately be pushed - to the bare clone using the git push command. - See the bulleted item - "Yocto Project Kernel" - for information on how to set up the bare clone. - Typically, Git workflows follow a scheme where changes made to a local area - are pulled into a Git repository. - However, because the git pull command does not work - with bare clones, this workflow pushes changes to the - repository even though you could use other more complicated methods to - get changes into the bare clone. - - - -
- -
- Setting Up the Local Source Directory - - - You can set up the - Source Directory - through tarball extraction or by - cloning the poky Git repository. - This example uses poky as the root directory of the - local Source Directory. - See the bulleted item - "Yocto Project Release" - for information on how to get these files. - - - - Once you have Source Directory set up, - you have many development branches from which you can work. - From inside the local repository you can see the branch names and the tag names used - in the upstream Git repository by using either of the following commands: - - $ cd poky - $ git branch -a - $ git tag -l - - This example uses the Yocto Project &DISTRO; Release code named "&DISTRO_NAME;", - which maps to the &DISTRO_NAME; branch in the repository. - The following commands create and checkout the local &DISTRO_NAME; - branch: - - $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; - Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. - Switched to a new branch '&DISTRO_NAME;' - - -
- -
- Setting Up the Local poky-extras Git Repository - - - This example creates a local copy of the poky-extras Git - repository inside the poky Source Directory. - See the bulleted item "The - poky-extras Git Repository" - for information on how to set up a local copy of the - poky-extras repository. - - - - Because this example uses the Yocto Project &DISTRO; Release code - named "&DISTRO_NAME;", which maps to the &DISTRO_NAME; - branch in the repository, you need to be sure you are using that - branch for poky-extras. - The following commands create and checkout the local - branch you are using for the &DISTRO_NAME; - branch: - - $ cd ~/poky/poky-extras - $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME; - Branch &DISTRO_NAME; set up to track remote branch &DISTRO_NAME; from origin. - Switched to a new branch '&DISTRO_NAME;' - - -
- -
- Setting Up the Bare Clone and its Copy - - - This example modifies the linux-yocto-3.4 kernel. - Thus, you need to create a bare clone of that kernel and then make a copy of the - bare clone. - See the bulleted item - "Yocto Project Kernel" - for information on how to do that. - - - - The bare clone exists for the kernel build tools and simply as the receiving end - of git push - commands after you make edits and commits inside the copy of the clone. - The copy (my-linux-yocto-3.4-work in this example) has to have - a local branch created and checked out for your work. - This example uses common-pc-base as the local branch. - The following commands create and checkout the branch: - - $ cd ~/my-linux-yocto-3.4-work - $ git checkout -b standard-common-pc-base origin/standard/common-pc/base - Branch standard-common-pc-base set up to track remote branch - standard/common-pc/base from origin. - Switched to a new branch 'standard-common-pc-base' - - -
- -
- Building and Booting the Default QEMU Kernel Image - - - Before we make changes to the kernel source files, this example first builds the - default image and then boots it inside the QEMU emulator. - - Because a full build can take hours, you should check two variables in the - build directory that is created after you source the - &OE_INIT_FILE; script. - You can find these variables - BB_NUMBER_THREADS and PARALLEL_MAKE - in the build/conf directory in the - local.conf configuration file. - By default, these variables are commented out. - If your host development system supports multi-core and multi-thread capabilities, - you can uncomment these statements and set the variables to significantly shorten - the full build time. - As a guideline, set both BB_NUMBER_THREADS and - PARALLEL_MAKE to twice the number - of cores your machine supports. - - The following two commands source the build environment setup script - and build the default qemux86 image. - If necessary, the script creates the build directory: - - $ cd ~/poky - $ source &OE_INIT_FILE; - You had no conf/local.conf file. This configuration file has therefore been - created for you with some default values. You may wish to edit it to use a - different MACHINE (target hardware) or enable parallel build options to take - advantage of multiple cores for example. See the file for more information as - common configuration options are commented. - - The Yocto Project has extensive documentation about OE including a reference manual - which can be found at: - http://yoctoproject.org/documentation - - For more information about OpenEmbedded see their website: - http://www.openembedded.org/ - - You had no conf/bblayers.conf file. The configuration file has been created for - you with some default values. To add additional metadata layers into your - configuration please add entries to this file. - - The Yocto Project has extensive documentation about OE including a reference manual - which can be found at: - http://yoctoproject.org/documentation - - For more information about OpenEmbedded see their website: - http://www.openembedded.org/ - - - - ### Shell environment set up for builds. ### - - You can now run 'bitbake <target>>' - - Common targets are: - core-image-minimal - core-image-sato - meta-toolchain - meta-toolchain-sdk - adt-installer - meta-ide-support - - You can also run generated qemu images with a command like 'runqemu qemux86' - - - - - The following bitbake command starts the build: - - $ bitbake -k core-image-minimal - - Be sure to check the settings in the local.conf - before starting the build. - - - - After the build completes, you can start the QEMU emulator using the resulting image - qemux86 as follows: - - $ runqemu qemux86 - - - - - As the image boots in the emulator, console message and status output appears - across the terminal window. - Because the output scrolls by quickly, it is difficult to read. - To examine the output, you log into the system using the - login root with no password. - Once you are logged in, issue the following command to scroll through the - console output: - - # dmesg | less - - - - - Take note of the output as you will want to look for your inserted print command output - later in the example. - -
Changing the Source Code and Pushing it to the Bare Clone @@ -2150,13 +1851,6 @@
- - - - - - -
Updating Existing Images -- cgit v1.2.3-54-g00ecf