documentation: dev-manual - Edits to "Patching the Kernel" section.
Edits according to Darren Hart's feedback. Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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Scott Rifenbark
Richard Purdie
parent
0163821ef7
commit
90b7c0cb5b
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@ -1620,6 +1620,9 @@
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Furthermore, the <link linkend='build-directory'>Build Directory</link> is
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<filename>build</filename> and is located in <filename>poky</filename> and
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the kernel is based on the Linux 3.4 kernel.
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For general information on how to configure the most efficient build, see the
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"<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>" section
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in the Yocto Project Quick Start.
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</para>
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<section id='create-a-layer-for-your-changes'>
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@ -1654,11 +1657,6 @@
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section and the
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<ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink> variable
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for more information about where source is kept during a build.
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For this example, the directory that
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holds the temporary source code is here:
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<literallayout class='monospaced'>
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~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.4.11+git1+5bdc...85f-r4.3/linux
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</literallayout>
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</para>
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<para>
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@ -1693,6 +1691,9 @@
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<ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink> variables
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represent the version and revision for the
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<filename>linux-yocto</filename> recipe.
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The <filename>PV</filename> variable includes the Git meta and machine
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hashes, which make the directory name longer than you might
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expect.
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</note></para></listitem>
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<listitem><para><emphasis>Edit the source file</emphasis>:
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Edit the <filename>init/calibrate.c</filename> file to have the
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@ -1717,20 +1718,19 @@
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</literallayout></para></listitem>
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<listitem><para><emphasis>Stage and commit your changes</emphasis>:
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These Git commands list out the changed file, stage it, and then
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commit the files:
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commit the file:
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<literallayout class='monospaced'>
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$ git status
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$ git add init/calibrate.c
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$ git commit
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$ git commit -m "calibrate: Add printk example"
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</literallayout></para></listitem>
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<listitem><para><emphasis>Generate the patch file</emphasis>:
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This Git command creates the a patch file named
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<filename>0001-calibrate.c.patch</filename> in the current directory.
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<filename>0001-calibrate: Add printk example.patch</filename>
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in the current directory.
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<literallayout class='monospaced'>
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$ git format-patch HEAD~1
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</literallayout>
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<note>The name of the patch file is based on your commit summary
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line.</note>
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</para></listitem>
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</orderedlist>
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</para>
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@ -1776,7 +1776,7 @@
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<literallayout class='monospaced'>
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FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
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SRC_URI += "file://0001-calibrate.c.patch"
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SRC_URI += "file://0001-calibrate: Add printk example.patch"
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PRINC := "${@int(PRINC) + 1}"
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</literallayout>
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@ -1784,7 +1784,7 @@
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statements enable the OpenEmbedded build system to find the patch file.
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</para></listitem>
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<listitem><para><emphasis>Put the patch file in your layer</emphasis>:
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Move the <filename>0001-calibrate.c.patch</filename> file to
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Move the <filename>0001-calibrate: Add printk example.patch</filename> file to
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the <filename>meta-mylayer/recipes-kernel/linux/linux-yocto</filename>
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directory.</para></listitem>
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</orderedlist>
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@ -1799,22 +1799,14 @@
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Once you set up these build parameters, they do not have to change unless you
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change the target architecture of the machine you are building:
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<itemizedlist>
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<listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> The
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<filename>local.conf</filename> file in the build directory defines the build's
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target architecture.
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<listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> Your
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selected <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
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definition within the <filename>local.conf</filename> file in the build directory
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specifies the target architecture used when building the Linux kernel.
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By default, <filename>MACHINE</filename> is set to
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<filename>qemux86</filename>, which specifies a 32-bit
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<trademark class='registered'>Intel</trademark> Architecture
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target machine suitable for the QEMU emulator.
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In this example, <filename>MACHINE</filename> is correctly configured.
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</para></listitem>
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<listitem><para><emphasis>Optimize Build Time:</emphasis> Also in the
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<filename>local.conf</filename> file are two variables that can speed your
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build time if your host supports multi-core and multi-thread capabilities:
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<filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>.
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If the host system has multiple cores then you can optimize build time
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by setting both these variables to twice the number of
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cores.</para></listitem>
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target machine suitable for the QEMU emulator.</para></listitem>
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<listitem><para><emphasis>Identify Your <filename>meta-mylayer</filename>
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Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the
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<filename>bblayers.conf</filename> file found in the
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@ -1847,22 +1839,23 @@
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<listitem><para><emphasis>Be sure your build environment is initialized</emphasis>:
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Your environment should be set up since you previously sourced
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the <filename>&OE_INIT_FILE;</filename> script.
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If it isn't, source the script again from <filename>poky</filename>.
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If it is not, source the script again from <filename>poky</filename>.
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<literallayout class='monospaced'>
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$ cd ~/poky
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$ source &OE_INIT_FILE;
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</literallayout>
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</para></listitem>
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<listitem><para><emphasis>Clean up</emphasis>:
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Be sure old images are cleaned out by running the
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<filename>cleanall</filename> BitBake task as follows from your build directory:
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Be sure to clean the shared state out by running the
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<filename>cleansstate</filename> BitBake task as follows from your build directory:
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<literallayout class='monospaced'>
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$ bitbake -c cleanall linux-yocto
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$ bitbake -c cleansstate linux-yocto
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</literallayout></para>
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<para><note>Never remove any files by hand from the <filename>tmp/deploy</filename>
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directory inside the build directory.
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Always use the BitBake <filename>cleanall</filename> task to clear
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out previous builds.</note></para></listitem>
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Always use the various BitBake clean tasks to clear out previous
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build artifacts.
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</note></para></listitem>
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<listitem><para><emphasis>Build the image</emphasis>:
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Next, build the kernel image using this command:
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<literallayout class='monospaced'>
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