Furthermore, the <link linkend='build-directory'>Build Directory</link> is
<filename>build</filename> and is located in <filename>poky</filename> and
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>
<section id='create-a-layer-for-your-changes'>
section and the
<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 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>
<ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink> variables
represent the version and revision for the
<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>
<listitem><para><emphasis>Edit the source file</emphasis>:
Edit the <filename>init/calibrate.c</filename> file to have the
</literallayout></para></listitem>
<listitem><para><emphasis>Stage and commit your changes</emphasis>:
These Git commands list out the changed file, stage it, and then
- commit the files:
+ commit the file:
<literallayout class='monospaced'>
$ git status
$ git add init/calibrate.c
- $ git commit
+ $ git commit -m "calibrate: Add printk example"
</literallayout></para></listitem>
<listitem><para><emphasis>Generate the patch file</emphasis>:
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'>
$ git format-patch HEAD~1
</literallayout>
- <note>The name of the patch file is based on your commit summary
- line.</note>
</para></listitem>
</orderedlist>
</para>
<literallayout class='monospaced'>
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
- SRC_URI += "file://0001-calibrate.c.patch"
+ SRC_URI += "file://0001-calibrate: Add printk example.patch"
PRINC := "${@int(PRINC) + 1}"
</literallayout>
statements enable the OpenEmbedded build system to find the patch file.
</para></listitem>
<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>
directory.</para></listitem>
</orderedlist>
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:
<itemizedlist>
- <listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> The
- <filename>local.conf</filename> file in the build directory defines the build's
- target architecture.
+ <listitem><para><emphasis>Build for the Correct Target Architecture:</emphasis> Your
+ selected <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
+ 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
<filename>qemux86</filename>, which specifies a 32-bit
<trademark class='registered'>Intel</trademark> Architecture
- target machine suitable for the QEMU emulator.
- 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>
+ target machine suitable for the QEMU emulator.</para></listitem>
<listitem><para><emphasis>Identify Your <filename>meta-mylayer</filename>
Layer:</emphasis> The <filename>BBLAYERS</filename> variable in the
<filename>bblayers.conf</filename> file found in the
<listitem><para><emphasis>Be sure your build environment is initialized</emphasis>:
Your environment should be set up since you previously sourced
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'>
$ cd ~/poky
$ source &OE_INIT_FILE;
</literallayout>
</para></listitem>
<listitem><para><emphasis>Clean up</emphasis>:
- Be sure old images are cleaned out by running the
- <filename>cleanall</filename> BitBake task as follows from your build directory:
+ Be sure to clean the shared state out by running the
+ <filename>cleansstate</filename> BitBake task as follows from your build directory:
<literallayout class='monospaced'>
- $ bitbake -c cleanall linux-yocto
+ $ bitbake -c cleansstate linux-yocto
</literallayout></para>
<para><note>Never remove any files by hand from the <filename>tmp/deploy</filename>
directory inside the build directory.
- Always use the BitBake <filename>cleanall</filename> task to clear
- out previous builds.</note></para></listitem>
+ Always use the various BitBake clean tasks to clear out previous
+ build artifacts.
+ </note></para></listitem>
<listitem><para><emphasis>Build the image</emphasis>:
Next, build the kernel image using this command:
<literallayout class='monospaced'>
projects / thirdparty / openembedded / openembedded-core-contrib.git / commitdiff
