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Diffstat (limited to 'poky/documentation/kernel-dev/advanced.rst')
| -rw-r--r-- | poky/documentation/kernel-dev/advanced.rst | 87 |
1 files changed, 29 insertions, 58 deletions
diff --git a/poky/documentation/kernel-dev/advanced.rst b/poky/documentation/kernel-dev/advanced.rst index fb6dfca85..b0d03851b 100644 --- a/poky/documentation/kernel-dev/advanced.rst +++ b/poky/documentation/kernel-dev/advanced.rst @@ -67,8 +67,7 @@ to indicate the branch. .. note:: You can use the ``KBRANCH`` value to define an alternate branch typically - with a machine override as shown here from the ``meta-yocto-bsp`` layer: - :: + with a machine override as shown here from the ``meta-yocto-bsp`` layer:: KBRANCH_edgerouter = "standard/edgerouter" @@ -106,15 +105,13 @@ You can use the variable to include features (configuration fragments, patches, or both) that are not already included by the ``KMACHINE`` and ``LINUX_KERNEL_TYPE`` variable combination. For example, to include a -feature specified as "features/netfilter/netfilter.scc", specify: -:: +feature specified as "features/netfilter/netfilter.scc", specify:: KERNEL_FEATURES += "features/netfilter/netfilter.scc" To include a feature called "cfg/sound.scc" just for the ``qemux86`` machine, -specify: -:: +specify:: KERNEL_FEATURES_append_qemux86 = " cfg/sound.scc" @@ -157,8 +154,7 @@ types to form the final description of what will be assembled and built. While the kernel Metadata syntax does not enforce any logical separation of configuration fragments, patches, features or kernel types, best practices dictate a logical separation of these types of Metadata. The -following Metadata file hierarchy is recommended: -:: +following Metadata file hierarchy is recommended:: base/ bsp/ @@ -222,8 +218,7 @@ used with the ``linux-yocto-4.12`` kernel as defined outside of the recipe space (i.e. ``yocto-kernel-cache``). This Metadata consists of two files: ``smp.scc`` and ``smp.cfg``. You can find these files in the ``cfg`` directory of the ``yocto-4.12`` branch in the -``yocto-kernel-cache`` Git repository: -:: +``yocto-kernel-cache`` Git repository:: cfg/smp.scc: define KFEATURE_DESCRIPTION "Enable SMP for 32 bit builds" @@ -265,8 +260,7 @@ non-hardware fragment. As described in the ":ref:`kernel-dev/common:validating configuration`" section, you can -use the following BitBake command to audit your configuration: -:: +use the following BitBake command to audit your configuration:: $ bitbake linux-yocto -c kernel_configcheck -f @@ -287,8 +281,7 @@ in the ``patches/build`` directory of the ``yocto-4.12`` branch in the ``yocto-kernel-cache`` Git repository. The following listings show the ``build.scc`` file and part of the -``modpost-mask-trivial-warnings.patch`` file: -:: +``modpost-mask-trivial-warnings.patch`` file:: patches/build/build.scc: patch arm-serialize-build-targets.patch @@ -334,8 +327,7 @@ Features Features are complex kernel Metadata types that consist of configuration fragments, patches, and possibly other feature description files. As an -example, consider the following generic listing: -:: +example, consider the following generic listing:: features/myfeature.scc define KFEATURE_DESCRIPTION "Enable myfeature" @@ -371,15 +363,13 @@ the ``linux-yocto_4.12.bb`` kernel recipe found in ``poky/meta/recipes-kernel/linux``, a :ref:`require <bitbake:bitbake-user-manual/bitbake-user-manual-metadata:\`\`require\`\` directive>` directive includes the ``poky/meta/recipes-kernel/linux/linux-yocto.inc`` file, -which has the following statement that defines the default kernel type: -:: +which has the following statement that defines the default kernel type:: LINUX_KERNEL_TYPE ??= "standard" Another example would be the real-time kernel (i.e. ``linux-yocto-rt_4.12.bb``). This kernel recipe directly sets the kernel -type as follows: -:: +type as follows:: LINUX_KERNEL_TYPE = "preempt-rt" @@ -412,8 +402,7 @@ for Linux Yocto kernels: For any given kernel type, the Metadata is defined by the ``.scc`` (e.g. ``standard.scc``). Here is a partial listing for the ``standard.scc`` file, which is found in the ``ktypes/standard`` directory of the -``yocto-kernel-cache`` Git repository: -:: +``yocto-kernel-cache`` Git repository:: # Include this kernel type fragment to get the standard features and # configuration values. @@ -482,15 +471,13 @@ Description Overview For simplicity, consider the following root BSP layer description files for the BeagleBone board. These files employ both a structure and naming convention for consistency. The naming convention for the file is as -follows: -:: +follows:: bsp_root_name-kernel_type.scc Here are some example root layer BSP filenames for the BeagleBone Board BSP, which is supported by the -Yocto Project: -:: +Yocto Project:: beaglebone-standard.scc beaglebone-preempt-rt.scc @@ -498,8 +485,7 @@ Yocto Project: Each file uses the root name (i.e "beaglebone") BSP name followed by the kernel type. -Examine the ``beaglebone-standard.scc`` file: -:: +Examine the ``beaglebone-standard.scc`` file:: define KMACHINE beaglebone define KTYPE standard @@ -533,8 +519,7 @@ description file match. To separate your kernel policy from your hardware configuration, you include a kernel type (``ktype``), such as "standard". In the previous -example, this is done using the following: -:: +example, this is done using the following:: include ktypes/standard/standard.scc @@ -544,13 +529,11 @@ policy. See the ":ref:`kernel-dev/advanced:kernel types`" section for more information. To aggregate common configurations and features specific to the kernel -for `mybsp`, use the following: -:: +for `mybsp`, use the following:: include mybsp.scc -You can see that in the BeagleBone example with the following: -:: +You can see that in the BeagleBone example with the following:: include beaglebone.scc @@ -558,15 +541,13 @@ For information on how to break a complete ``.config`` file into the various configuration fragments, see the ":ref:`kernel-dev/common:creating configuration fragments`" section. Finally, if you have any configurations specific to the hardware that -are not in a ``*.scc`` file, you can include them as follows: -:: +are not in a ``*.scc`` file, you can include them as follows:: kconf hardware mybsp-extra.cfg The BeagleBone example does not include these types of configurations. However, the Malta 32-bit board does -("mti-malta32"). Here is the ``mti-malta32-le-standard.scc`` file: -:: +("mti-malta32"). Here is the ``mti-malta32-le-standard.scc`` file:: define KMACHINE mti-malta32-le define KMACHINE qemumipsel @@ -623,8 +604,7 @@ found on the machine. This ``minnow.scc`` description file is then included in each of the three "minnow" description files for the supported kernel types (i.e. "standard", "preempt-rt", and "tiny"). Consider the "minnow" description for the "standard" kernel type (i.e. -``minnow-standard.scc``): -:: +``minnow-standard.scc``):: define KMACHINE minnow define KTYPE standard @@ -656,8 +636,7 @@ that defines all enabled hardware for the BSP that is common to all kernel types. Using this command significantly reduces duplication. Now consider the "minnow" description for the "tiny" kernel type (i.e. -``minnow-tiny.scc``): -:: +``minnow-tiny.scc``):: define KMACHINE minnow define KTYPE tiny @@ -720,8 +699,7 @@ See the ":ref:`kernel-dev/common:modifying an existing recipe`" section for more information. Here is an example that shows a trivial tree of kernel Metadata stored -in recipe-space within a BSP layer: -:: +in recipe-space within a BSP layer:: meta-my_bsp_layer/ `-- recipes-kernel @@ -744,8 +722,7 @@ value when changing the content of files not explicitly listed in the If the BSP description is in recipe space, you cannot simply list the ``*.scc`` in the ``SRC_URI`` statement. You need to use the following -form from your kernel append file: -:: +form from your kernel append file:: SRC_URI_append_myplatform = " \ file://myplatform;type=kmeta;destsuffix=myplatform \ @@ -759,8 +736,7 @@ reside in a separate repository. The OpenEmbedded build system adds the Metadata to the build as a "type=kmeta" repository through the :term:`SRC_URI` variable. As an example, consider the following ``SRC_URI`` statement from the -``linux-yocto_4.12.bb`` kernel recipe: -:: +``linux-yocto_4.12.bb`` kernel recipe:: SRC_URI = "git://git.yoctoproject.org/linux-yocto-4.12.git;name=machine;branch=${KBRANCH}; \ git://git.yoctoproject.org/yocto-kernel-cache;type=kmeta;name=meta;branch=yocto-4.12;destsuffix=${KMETA}" @@ -844,14 +820,12 @@ patches into a feature. Once you have a new branch, you can set up your kernel Metadata to use the branch a couple different ways. In the recipe, you can specify the -new branch as the ``KBRANCH`` to use for the board as follows: -:: +new branch as the ``KBRANCH`` to use for the board as follows:: KBRANCH = "mynewbranch" Another method is to use the ``branch`` command in the BSP -description: -:: +description:: mybsp.scc: define KMACHINE mybsp @@ -865,15 +839,13 @@ description: If you find yourself with numerous branches, you might consider using a hierarchical branching system similar to what the Yocto Linux Kernel Git -repositories use: -:: +repositories use:: common/kernel_type/machine If you had two kernel types, "standard" and "small" for instance, three machines, and common as ``mydir``, the branches in your Git repository -might look like this: -:: +might look like this:: mydir/base mydir/standard/base @@ -905,8 +877,7 @@ that have to be regularly updated. The Yocto Project Linux kernel tools provide for this with the ``git merge`` command. To merge a feature branch into a BSP, insert the ``git merge`` command -after any ``branch`` commands: -:: +after any ``branch`` commands:: mybsp.scc: define KMACHINE mybsp |