ref-manual: Expanded kernel task descriptions.
Fixes [YOCTO #9376] Expanded many of the brief descriptions for the kernel-related tasks. (From yocto-docs rev: ee9e54aa9f148e5438cd9bdf7e55d7fa43cc3ec5) Signed-off-by: Scott Rifenbark <srifenbark@gmail.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Scott Rifenbark
Richard Purdie
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commit
27a9c9d788
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@ -853,7 +853,10 @@
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<title><filename>do_compile_kernelmodules</filename></title>
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<para>
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Compiles loadable modules for the Linux kernel.
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Runs the step that builds the kernel modules (if needed).
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Building a kernel consists of two steps: 1) the kernel
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(<filename>vmlinux</filename>) is built, and 2) the modules
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are built (i.e. <filename>make modules</filename>).
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</para>
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</section>
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@ -861,9 +864,21 @@
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<title><filename>do_diffconfig</filename></title>
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<para>
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Compares the old and new config files after running the
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<link linkend='ref-tasks-menuconfig'><filename>do_menuconfig</filename></link>
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task for the kernel.
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When invoked by the user, this task creates a file containing the
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differences between the original config as produced by
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<link linkend='ref-tasks-kernel_configme'><filename>do_kernel_configme</filename></link>
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task and the changes made by the user with other methods
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(i.e. using
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(<link linkend='ref-tasks-kernel_menuconfig'><filename>do_kernel_menuconfig</filename></link>).
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Once the file of differences is created, it can be used to create
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a config fragment that only contains the differences.
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You can invoke this task from the command line as follows:
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<literallayout class='monospaced'>
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$ bitbake linux-yocto -c diffconfig
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</literallayout>
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For more information, see the
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"<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'>Generating Configuration Files</ulink>"
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section in the Yocto Project Linux Kernel Development Manual.
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</para>
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</section>
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@ -871,7 +886,12 @@
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<title><filename>do_kernel_checkout</filename></title>
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<para>
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Checks out source/meta branches for a linux-yocto style kernel.
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Converts the newly unpacked kernel source into a form with which
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the OpenEmbedded build system can work.
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Because the kernel source can be fetched in several different ways,
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the <filename>do_kernel_checkout</filename> task makes sure that
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subsequent tasks are given a clean working tree copy of the kernel
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with the correct branches checked out.
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</para>
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</section>
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@ -879,7 +899,21 @@
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<title><filename>do_kernel_configcheck</filename></title>
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<para>
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Validates the kernel configuration for a linux-yocto style kernel.
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Validates the configuration produced by the
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<link linkend='ref-tasks-kernel_menuconfig'><filename>do_kernel_menuconfig</filename></link>
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task.
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The <filename>do_kernel_configcheck</filename> task produces
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warnings when a requested configuration does not appear in the
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final <filename>.config</filename> file or when you override a
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policy configuration in a hardware configuration fragment.
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You can run this task explicitly and view the output by using
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the following command:
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<literallayout class='monospaced'>
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$ bitbake linux-yocto -c kernel_configcheck -f
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</literallayout>
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For more information, see the
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"<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'>Generating Configuration Files</ulink>"
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section in the Yocto Project Linux Kernel Development Manual.
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</para>
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</section>
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@ -887,17 +921,41 @@
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<title><filename>do_kernel_configme</filename></title>
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<para>
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Assembles the kernel configuration for a linux-yocto style kernel.
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After the kernel is patched by the
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<link linkend='ref-tasks-patch'><filename>do_patch</filename></link>
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task, the <filename>do_kernel_configme</filename> task assembles
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and merges all the kernel config fragments into a merged
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configuration that can then be passed to the kernel configuration
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phase proper.
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This is also the time during which user-specified defconfigs
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are applied if present, and where configuration modes such as
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<filename>--allnoconfig</filename> are applied.
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</para>
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</section>
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<section id='ref-tasks-kernel_link_vmlinux'>
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<title><filename>do_kernel_link_vmlinux</filename></title>
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<section id='ref-tasks-kernel_menuconfig'>
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<title><filename>do_kernel_menuconfig</filename></title>
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<para>
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Creates a symbolic link in
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<filename>arch/$arch/boot</filename> for vmlinux kernel
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images.
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Invoked by the user to manipulate the
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<filename>.config</filename> file used to build a linux-yocto
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recipe.
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This task starts the Linux kernel configuration tool, which you
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then use to modify the kernel configuration.
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<note>
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You can also invoke this tool from the command line as
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follows:
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<literallayout class='monospaced'>
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$ bitbake linux-yocto -c menuconfig
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</literallayout>
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</note>
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See the
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"<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#generating-configuration-files'>Generating Configuration Files</ulink>"
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section in the Yocto Project Linux Kernel Development Manual
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for more information on this configuration tool.
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You can also reference the
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"<ulink url='&YOCTO_DOCS_DEV_URL;#using-menuconfig'>Using <filename>menuconfig</filename></ulink>"
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section in the Yocto Project Development Manual.
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</para>
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</section>
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@ -905,8 +963,16 @@
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<title><filename>do_kernel_metadata</filename></title>
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<para>
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Collects kernel metadata for a
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<filename>linux-yocto</filename> style kernel.
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Collects all the features required for a given kernel build,
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whether the features come from
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<link linkend='var-SRC_URI'><filename>SRC_URI</filename></link>
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or from Git repositories.
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After collection, the <filename>do_kernel_metadata</filename> task
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processes the features into a series of config fragments and
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patches, which can then be applied by subsequent tasks such as
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<link linkend='ref-tasks-patch'><filename>do_patch</filename></link>
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and
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<link linkend='ref-tasks-kernel_configme'><filename>do_kernel_configme</filename></link>.
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</para>
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</section>
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@ -925,7 +991,17 @@
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<title><filename>do_savedefconfig</filename></title>
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<para>
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Creates a minimal Linux kernel configuration file.
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When invoked by the user, creates a defconfig file that can be
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used instead of the default defconfig.
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The saved defconfig contains the differences between the default
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defconfig and the changes made by the user using other methods
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(i.e. the
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<link linkend='ref-tasks-kernel_menuconfig'><filename>do_kernel_menuconfig</filename></link>
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task.
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You can invoke the task using the following command:
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<literallayout class='monospaced'>
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$ bitbake linux-yocto -c savedefconfig
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</literallayout>
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</para>
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</section>
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@ -933,7 +1009,14 @@
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<title><filename>do_shared_workdir</filename></title>
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<para>
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Creates the shared working directory for the kernel.
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After the kernel has been compiled but before the kernel modules
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have been compiled, this task copies files required for module
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builds and which are generated from the kernel build into the
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shared work directory.
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With these copies successfully copied, the
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<link linkend='ref-tasks-compile_kernelmodules'><filename>do_compile_kernelmodules</filename></link>
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task can successfully build the kernel modules in the next step
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of the build.
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</para>
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</section>
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@ -941,9 +1024,12 @@
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<title><filename>do_sizecheck</filename></title>
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<para>
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Checks the size of the kernel image against
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<link linkend='var-KERNEL_IMAGE_MAXSIZE'><filename>KERNEL_IMAGE_MAXSIZE</filename></link>
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when set.
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After the kernel has been built, this task checks the size of the
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stripped kernel image against
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<link linkend='var-KERNEL_IMAGE_MAXSIZE'><filename>KERNEL_IMAGE_MAXSIZE</filename></link>.
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If that variable was set and the size of the stripped kernel
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exceeds that size, the kernel build produces a warning to that
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effect.
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</para>
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</section>
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@ -951,15 +1037,13 @@
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<title><filename>do_strip</filename></title>
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<para>
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Strips unneeded sections out of the Linux kernel image.
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</para>
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</section>
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<section id='ref-tasks-uboot_mkimage'>
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<title><filename>do_uboot_mkimage</filename></title>
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<para>
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Creates a uImage file from the kernel for the U-Boot bootloader.
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If
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<filename>KERNEL_IMAGE_STRIP_EXTRA_SECTIONS</filename> is defined,
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this task strips the sections named in that variable from
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<filename>vmlinux</filename>.
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This stripping is typically used to remove nonessential sections
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such as <filename>.comment</filename> sections from a
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size-sensitive configuration.
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</para>
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</section>
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@ -967,10 +1051,14 @@
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<title><filename>do_validate_branches</filename></title>
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<para>
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Ensures that the source, metadata (or both) branches are on the
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locations specified by their
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<link linkend='var-SRCREV'><filename>SRCREV</filename></link>
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values for a linux-yocto style kernel.
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After the kernel is unpacked but before it is patched, this task
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makes sure that the machine and metadata branches as specified
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by the <link linkend='var-SRCREV'><filename>SRCREV</filename></link>
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variables actually exist on the specified branches.
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If these branches do not exist and
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<link linkend='var-AUTOREV'><filename>AUTOREV</filename></link>
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is not being used, the <filename>do_validate_branches</filename>
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task fails during the build.
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</para>
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</section>
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</section>
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