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| -rw-r--r-- | documentation/bsp-guide/bsp.xml | 69 |
1 files changed, 40 insertions, 29 deletions
diff --git a/documentation/bsp-guide/bsp.xml b/documentation/bsp-guide/bsp.xml index 94dd5160a..cf9c91f4b 100644 --- a/documentation/bsp-guide/bsp.xml +++ b/documentation/bsp-guide/bsp.xml @@ -319,46 +319,57 @@ meta-<bsp_name>/recipes-kernel/linux/linux-wrs_git.bbappend </programlisting> <para> - These files make up the definition of a kernel to use with this hardware. - In this case, it is a complete self-contained kernel with its own - configuration and patches. - However, kernels can be shared between many machines as well. - Following is an example: - <programlisting> -meta-emenlow/recipes-kernel/linux/linux-bsp_2.6.50.bb - </programlisting> - This example file is the core kernel recipe that details from where to get the kernel - source. - All standard source code locations are supported. - Consequently, the source could be a release tarball, a git repository, or source included in - the directory within the BSP itself. - </para> - <para> - The file then contains information about what patches to apply and how to configure and build them. - Because the file can reuse the main Poky kernel build class, the definitions here can - remain very simple. + This file appends your specific changes to the kernel you are using. </para> <para> - <programlisting> -linux-bsp-2.6.50/*.patch - </programlisting> + For your BSP you typically want to use an existing Poky kernel found in the + Poky repository at <filename class='directory'>meta/recipes-kernel/kernel</filename>. + You can append your specific changes to the kernel by using a + <filename>.bbappend</filename> file, which is located in the + <filename class='directory'>meta-<bsp_name>/recipes-kernel/linux</filename> + directory. </para> <para> - The above example file contains patches you can apply against the base kernel, from wherever - they may have been obtained. + Consider a BSP that uses the <filename>linux-yocto-stable_git.bb</filename> kernel. + You would use the <filename>linux-yocto-stable_git.bbappend</filename> file to add + specific BSP settings to the kernel, thus configuring the kernel for your particular BSP. </para> <para> + Consider an example for the existing "crownbay" BSP. + The <filename>.bbaappend</filename> file used for the "crownbay" BSP is: + <programlisting> +meta-crownbay/recipes-kernel/linux/linux-wrs_git.bbappend + </programlisting> + The file contains the following: <programlisting> -meta-emenlow/recipes-kernel/linux/linux-bsp-2.6.50/defconfig-bsp +FILESEXTRAPATHS := "${THISDIR}/${PN}" +COMPATIBLE_MACHINE_crownbay = "cronwbay" +KMACHINE_crownbay = "crownbay" </programlisting> + This <filename>.bbappend</filename> file adds "crownbay" as a compatible machine, + and additionally sets a Yocto Kernel-specific variable that identifies the name of the + BSP branch to use in the GIT repository to find configuration information. </para> - <para> - Finally, this last example file contains kernel configuration information. + <note><para> + For an established BSP the configuration information is incorporated directly into the + git tree. + For a new BSP, however, the <filename>.bbappend</filename> file needs to + include its own set of configuration options in a file called + <filename>defconfig</filename> located in a directory that matches the recipe name. + <programlisting> +SRC_URI += "file://defconfig" + </programlisting> + Once a BSP is committed, the Yocto kernel maintainer moves this configuration information + into the git tree so that the <filename>.bbappend</filename> file does not need to locate + its own configuration options. + Again, the initial configuration options using the SRC_URI are put into a + directory named + <filename class='directory'>meta-<bsp_name>/recipes/linux/linux-yocto-stable</filename>. </para> <para> - Examples of kernel recipes are available in Poky itself, and thus, make these files optional. - However, it would be unusual not to have a kernel configuration. - </para> + You can find more information about creating a BSP that is based on an existing similar + BSP by reading the "Yocto Project Kernel Architecture and Use Manual." + </para></note> </section> <!-- <section id='bsp-filelayout-packages'> |