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Diffstat (limited to 'yocto-poky/documentation/kernel-dev/kernel-dev-common.xml')
| -rw-r--r-- | yocto-poky/documentation/kernel-dev/kernel-dev-common.xml | 128 |
1 files changed, 125 insertions, 3 deletions
diff --git a/yocto-poky/documentation/kernel-dev/kernel-dev-common.xml b/yocto-poky/documentation/kernel-dev/kernel-dev-common.xml index ab7f80fbe..261471c46 100644 --- a/yocto-poky/documentation/kernel-dev/kernel-dev-common.xml +++ b/yocto-poky/documentation/kernel-dev/kernel-dev-common.xml @@ -270,11 +270,12 @@ edit the recipe that builds your kernel so that it has the following command form: <literallayout class='monospaced'> - KBUILD_DEFCONFIG_<ulink url='&YOCTO_DOCS_REF_URL;#var-KMACHINE'>KMACHINE</ulink> ?= <replaceable>defconfig_file</replaceable> + KBUILD_DEFCONFIG_KMACHINE ?= <replaceable>defconfig_file</replaceable> </literallayout> You need to append the variable with - <filename>KMACHINE</filename> and then supply the path to - your "in-tree" <filename>defconfig</filename> file. + <ulink url='&YOCTO_DOCS_REF_URL;#var-KMACHINE'><filename>KMACHINE</filename></ulink> + and then supply the path to your "in-tree" + <filename>defconfig</filename> file. </para> <para> @@ -1031,6 +1032,127 @@ </para> </section> </section> + + <section id='adding-recipe-space-kernel-features'> + <title>Adding Recipe-Space Kernel Features</title> + + <para> + You can add kernel features in the + <link linkend='recipe-space-metadata'>recipe-space</link> by + using the + <ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_FEATURES'><filename>KERNEL_FEATURES</filename></ulink> + variable and by specifying the feature's <filename>.scc</filename> + file path in the + <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink> + statement. + When you add features using this method, the OpenEmbedded build + system checks to be sure the features are present. + If the features are not present, the build stops. + Kernel features are the last elements processed for configuring + and patching the kernel. + Therefore, adding features in this manner is a way + to enforce specific features are present and enabled + without needing to do a full audit of any other layer's additions + to the <filename>SRC_URI</filename> statement. + </para> + + <para> + You add a kernel feature by providing the feature as part of the + <filename>KERNEL_FEATURES</filename> variable and by providing the + path to the feature's <filename>.scc</filename> file, which is + relative to the root of the kernel Metadata. + The OpenEmbedded build system searches all forms of kernel + Metadata on the <filename>SRC_URI</filename> statement regardless + of whether the Metadata is in the "kernel-cache", system kernel + Metadata, or a recipe-space Metadata. + See the + "<link linkend='kernel-metadata-location'>Kernel Metadata Location</link>" + section for additional information. + </para> + + <para> + When you specify the feature's <filename>.scc</filename> file + on the <filename>SRC_URI</filename> statement, the OpenEmbedded + build system adds the directory of that + <filename>.scc</filename> file along with all its subdirectories + to the kernel feature search path. + Because subdirectories are searched, you can reference a single + <filename>.scc</filename> file in the + <filename>SRC_URI</filename> statement to reference multiple kernel + features. + </para> + + <para> + Consider the following example that adds the "test.scc" feature + to the build. + <orderedlist> + <listitem><para> + Create a <filename>.scc</filename> file and locate it + just as you would any other patch file, + <filename>.cfg</filename> file, or fetcher item + you specify in the <filename>SRC_URI</filename> + statement. + <note><title>Notes</title> + <itemizedlist> + <listitem><para> + You must add the directory of the + <filename>.scc</filename> file to the fetcher's + search path in the same manner as you would + add a <filename>.patch</filename> file. + </para></listitem> + <listitem><para> + You can create additional + <filename>.scc</filename> files beneath the + directory that contains the file you are + adding. + All subdirectories are searched during the + build as potential feature directories. + </para></listitem> + </itemizedlist> + </note> + Continuing with the example, suppose the "test.scc" + feature you are adding has a + <filename>test.scc</filename> file in the following + directory: + <literallayout class='monospaced'> + <replaceable>my_recipe</replaceable> + | + +-linux-yocto + | + +-test.cfg + +-test.scc + </literallayout> + In this example, the <filename>linux-yocto</filename> + directory has both the feature + <filename>test.scc</filename> file and a similarly + named configuration fragment file + <filename>test.cfg</filename>. + </para></listitem> + <listitem><para> + Add the <filename>.scc</filename> file to the + recipe's <filename>SRC_URI</filename> statement: + <literallayout class='monospaced'> + SRC_URI_append = " file://test.scc" + </literallayout> + The leading space before the path is important as the + path is appended to the existing path. + </para></listitem> + <listitem><para> + Specify the feature as a kernel feature: + <literallayout class='monospaced'> + KERNEL_FEATURES_append = " test.scc" + </literallayout> + The OpenEmbedded build system processes the kernel feature + when it builds the kernel. + <note> + If other features are contained below "test.scc", + then their directories are relative to the directory + containing the <filename>test.scc</filename> file. + </note> + </para></listitem> + </orderedlist> + </para> + </section> </chapter> <!-- vim: expandtab tw=80 ts=4 |