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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>
This commit is contained in:
Scott Rifenbark 2012-10-16 12:02:10 -07:00 committed by Richard Purdie
parent 0163821ef7
commit 90b7c0cb5b
1 changed files with 24 additions and 31 deletions
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55
documentation/dev-manual/dev-manual-common-tasks.xml
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@ -1620,6 +1620,9 @@
Furthermore, the <link linkend='build-directory'>Build Directory</link> is Furthermore, the <link linkend='build-directory'>Build Directory</link> is
<filename>build</filename> and is located in <filename>poky</filename> and <filename>build</filename> and is located in <filename>poky</filename> and
the kernel is based on the Linux 3.4 kernel. the kernel is based on the Linux 3.4 kernel.
For general information on how to configure the most efficient build, see the
"<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>" section
in the Yocto Project Quick Start.
</para> </para>
<section id='create-a-layer-for-your-changes'> <section id='create-a-layer-for-your-changes'>
@ -1654,11 +1657,6 @@
section and the section and the
<ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink> variable <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink> variable
for more information about where source is kept during a build. for more information about where source is kept during a build.
For this example, the directory that
holds the temporary source code is here:
<literallayout class='monospaced'>
~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.4.11+git1+5bdc...85f-r4.3/linux
</literallayout>
</para> </para>
<para> <para>
@ -1693,6 +1691,9 @@
<ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink> variables <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink> variables
represent the version and revision for the represent the version and revision for the
<filename>linux-yocto</filename> recipe. <filename>linux-yocto</filename> recipe.
The <filename>PV</filename> variable includes the Git meta and machine
hashes, which make the directory name longer than you might
expect.
</note></para></listitem> </note></para></listitem>
<listitem><para><emphasis>Edit the source file</emphasis>: <listitem><para><emphasis>Edit the source file</emphasis>:
Edit the <filename>init/calibrate.c</filename> file to have the Edit the <filename>init/calibrate.c</filename> file to have the
@ -1717,20 +1718,19 @@
</literallayout></para></listitem> </literallayout></para></listitem>
<listitem><para><emphasis>Stage and commit your changes</emphasis>: <listitem><para><emphasis>Stage and commit your changes</emphasis>:
These Git commands list out the changed file, stage it, and then These Git commands list out the changed file, stage it, and then
commit the files: commit the file:
<literallayout class='monospaced'> <literallayout class='monospaced'>
$ git status $ git status
$ git add init/calibrate.c $ git add init/calibrate.c
$ git commit $ git commit -m "calibrate: Add printk example"
</literallayout></para></listitem> </literallayout></para></listitem>
<listitem><para><emphasis>Generate the patch file</emphasis>: <listitem><para><emphasis>Generate the patch file</emphasis>:
This Git command creates the a patch file named This Git command creates the a patch file named
<filename>0001-calibrate.c.patch</filename> in the current directory. <filename>0001-calibrate: Add printk example.patch</filename>
in the current directory.
<literallayout class='monospaced'> <literallayout class='monospaced'>
$ git format-patch HEAD~1 $ git format-patch HEAD~1
</literallayout> </literallayout>
<note>The name of the patch file is based on your commit summary
line.</note>
</para></listitem> </para></listitem>
</orderedlist> </orderedlist>
</para> </para>
@ -1776,7 +1776,7 @@
<literallayout class='monospaced'> <literallayout class='monospaced'>
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
SRC_URI += "file://0001-calibrate.c.patch" SRC_URI += "file://0001-calibrate: Add printk example.patch"
PRINC := "${@int(PRINC) + 1}" PRINC := "${@int(PRINC) + 1}"
</literallayout> </literallayout>
@ -1784,7 +1784,7 @@
statements enable the OpenEmbedded build system to find the patch file. statements enable the OpenEmbedded build system to find the patch file.
</para></listitem> </para></listitem>
<listitem><para><emphasis>Put the patch file in your layer</emphasis>: <listitem><para><emphasis>Put the patch file in your layer</emphasis>:
Move the <filename>0001-calibrate.c.patch</filename> file to Move the <filename>0001-calibrate: Add printk example.patch</filename> file to
the <filename>meta-mylayer/recipes-kernel/linux/linux-yocto</filename> the <filename>meta-mylayer/recipes-kernel/linux/linux-yocto</filename>
directory.</para></listitem> directory.</para></listitem>
</orderedlist> </orderedlist>
@ -1799,22 +1799,14 @@
Once you set up these build parameters, they do not have to change unless you Once you set up these build parameters, they do not have to change unless you
change the target architecture of the machine you are building: change the target architecture of the machine you are building:
<itemizedlist> <itemizedlist>
<listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> The <listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> Your
<filename>local.conf</filename> file in the build directory defines the build's selected <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
target architecture. definition within the <filename>local.conf</filename> file in the build directory
specifies the target architecture used when building the Linux kernel.
By default, <filename>MACHINE</filename> is set to By default, <filename>MACHINE</filename> is set to
<filename>qemux86</filename>, which specifies a 32-bit <filename>qemux86</filename>, which specifies a 32-bit
<trademark class='registered'>Intel</trademark> Architecture <trademark class='registered'>Intel</trademark> Architecture
target machine suitable for the QEMU emulator. target machine suitable for the QEMU emulator.</para></listitem>
In this example, <filename>MACHINE</filename> is correctly configured.
</para></listitem>
<listitem><para><emphasis>Optimize Build Time:</emphasis> Also in the
<filename>local.conf</filename> file are two variables that can speed your
build time if your host supports multi-core and multi-thread capabilities:
<filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>.
If the host system has multiple cores then you can optimize build time
by setting both these variables to twice the number of
cores.</para></listitem>
<listitem><para><emphasis>Identify Your <filename>meta-mylayer</filename> <listitem><para><emphasis>Identify Your <filename>meta-mylayer</filename>
Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the
<filename>bblayers.conf</filename> file found in the <filename>bblayers.conf</filename> file found in the
@ -1847,22 +1839,23 @@
<listitem><para><emphasis>Be sure your build environment is initialized</emphasis>: <listitem><para><emphasis>Be sure your build environment is initialized</emphasis>:
Your environment should be set up since you previously sourced Your environment should be set up since you previously sourced
the <filename>&OE_INIT_FILE;</filename> script. the <filename>&OE_INIT_FILE;</filename> script.
If it isn't, source the script again from <filename>poky</filename>. If it is not, source the script again from <filename>poky</filename>.
<literallayout class='monospaced'> <literallayout class='monospaced'>
$ cd ~/poky $ cd ~/poky
$ source &OE_INIT_FILE; $ source &OE_INIT_FILE;
</literallayout> </literallayout>
</para></listitem> </para></listitem>
<listitem><para><emphasis>Clean up</emphasis>: <listitem><para><emphasis>Clean up</emphasis>:
Be sure old images are cleaned out by running the Be sure to clean the shared state out by running the
<filename>cleanall</filename> BitBake task as follows from your build directory: <filename>cleansstate</filename> BitBake task as follows from your build directory:
<literallayout class='monospaced'> <literallayout class='monospaced'>
$ bitbake -c cleanall linux-yocto $ bitbake -c cleansstate linux-yocto
</literallayout></para> </literallayout></para>
<para><note>Never remove any files by hand from the <filename>tmp/deploy</filename> <para><note>Never remove any files by hand from the <filename>tmp/deploy</filename>
directory inside the build directory. directory inside the build directory.
Always use the BitBake <filename>cleanall</filename> task to clear Always use the various BitBake clean tasks to clear out previous
out previous builds.</note></para></listitem> build artifacts.
</note></para></listitem>
<listitem><para><emphasis>Build the image</emphasis>: <listitem><para><emphasis>Build the image</emphasis>:
Next, build the kernel image using this command: Next, build the kernel image using this command:
<literallayout class='monospaced'> <literallayout class='monospaced'>