589 lines
25 KiB
XML
589 lines
25 KiB
XML
<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<appendix id='faq'>
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<title>FAQ</title>
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<qandaset>
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<qandaentry>
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<question>
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<para>
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How does Poky differ from <ulink url='http://www.openembedded.org/'>OpenEmbedded</ulink>?
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</para>
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</question>
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<answer>
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<para>
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Poky is the Yocto Project build system that was derived from <ulink
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url='http://www.openembedded.org/'>OpenEmbedded</ulink>.
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Poky is a stable, smaller subset focused on the mobile environment.
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Development in the Yocto Project using Poky is closely tied to OpenEmbedded with
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features being merged regularly between the two for mutual benefit.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I only have Python 2.4 or 2.5 but BitBake requires Python 2.6 or 2.7.
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Can I still use the Yocto Project?
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</para>
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</question>
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<answer>
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<para>
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You can use a stand-alone tarball to provide Python 2.6.
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You can find pre-built 32 and 64-bit versions of Python 2.6 at the following locations:
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<itemizedlist>
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<listitem><para><ulink url='http://downloads.yoctoproject.org/releases/miscsupport/yocto-1.0-python-nativesdk/python-nativesdk-standalone-i686.tar.bz2'>32-bit tarball</ulink></para></listitem>
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<listitem><para><ulink url='http://downloads.yoctoproject.org/releases/miscsupport/yocto-1.0-python-nativesdk/python-nativesdk-standalone-x86_64.tar.bz2'>64-bit tarball</ulink></para></listitem>
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</itemizedlist>
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</para>
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<para>
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These tarballs are self-contained with all required libraries and should work
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on most Linux systems.
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To use the tarballs extract them into the root
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directory and run the appropriate command:
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<literallayout class='monospaced'>
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$ export PATH=/opt/poky/sysroots/i586-pokysdk-linux/usr/bin/:$PATH
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$ export PATH=/opt/poky/sysroots/x86_64-pokysdk-linux/usr/bin/:$PATH
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</literallayout>
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</para>
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<para>
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Once you run the command, BitBake uses Python 2.6.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How can you claim Poky is stable?
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</para>
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</question>
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<answer>
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<para>
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There are three areas that help with stability;
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<itemizedlist>
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<listitem><para>The Yocto Project team keeps Poky small and focused.
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It contains around 650 packages as compared to over 5000 for full
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OpenEmbedded.</para></listitem>
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<listitem><para>The Yocto Project only supports hardware that the
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team has access to for testing.</para></listitem>
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<listitem><para>The Yocto Project uses an an autobuilder,
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which provides continuous build and integration tests.</para></listitem>
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</itemizedlist>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I get support for my board added to the Yocto Project?
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</para>
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</question>
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<answer>
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<para>
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There are two main ways to get a board supported in the Yocto Project;
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<itemizedlist>
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<listitem><para>Send the Yocto Project team information on the board
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and if the team does not have it yet they will consider adding it.</para></listitem>
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<listitem><para>Send the Yocto Project team the BitBake recipes if you have them.
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</para></listitem>
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</itemizedlist>
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Usually, if the board is not completely exotic, adding support in
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the Yocto Project is fairly straightforward.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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Are there any products using Poky?
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</para>
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</question>
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<answer>
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<para>
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The <ulink url='http://vernier.com/labquest/'>Vernier LabQuest</ulink> is using
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the Yocto Project build system Poky.
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See the <ulink url='http://www.vernier.com/products/interfaces/labq/'>Vernier LabQuest</ulink>
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for more information.
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There are a number of pre-production devices using Poky and the Yocto Project team
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announces them as soon as they are released.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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What does the Yocto Project build system Poky produce as output?
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</para>
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</question>
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<answer>
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<para>
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Because the same set of recipes can be used to create output of various formats, the
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output of a Yocto Project build depends on how it was started.
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Usually, the output is a flashable image ready for the target device.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I add my package to the Yocto Project?
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</para>
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</question>
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<answer>
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<para>
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To add a package, you need to create a BitBake recipe.
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For information on how to add a package, see the
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<link linkend='usingpoky-extend-addpkg'>Adding a Package</link> section
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earlier in this manual.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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Do I have to reflash my entire board with a new Yocto Project image when recompiling
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a package?
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</para>
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</question>
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<answer>
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<para>
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The Yocto Project can build packages in various formats such as
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<filename>ipk</filename> for <filename>ipkg</filename>/<filename>opkg</filename>,
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Debian package (<filename>.deb</filename>), or RPM.
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The packages can then be upgraded using the package tools on the device, much like
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on a desktop distribution such as Ubuntu or Fedora.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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What is GNOME Mobile and what is the difference between GNOME Mobile and GNOME?
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</para>
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</question>
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<answer>
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<para>
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<ulink url='http://www.gnome.org/mobile/'>GNOME Mobile</ulink> is a subset of the GNOME
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platform targeted at mobile and embedded devices.
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The the main difference between GNOME Mobile and standard GNOME is that
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desktop-orientated libraries have been removed, along with deprecated libraries,
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creating a much smaller footprint.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I see the error '<filename>chmod: XXXXX new permissions are r-xrwxrwx, not r-xr-xr-x</filename>'.
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What is wrong?
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</para>
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</question>
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<answer>
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<para>
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You are probably running the build on an NTFS filesystem.
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Use <filename>ext2</filename>, <filename>ext3</filename>, or <filename>ext4</filename> instead.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I make the Yocto Project work in RHEL/CentOS?
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</para>
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</question>
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<answer>
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<para>
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To get the Yocto Project working under RHEL/CentOS 5.1 you need to first
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install some required packages.
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The standard CentOS packages needed are:
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<itemizedlist>
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<listitem><para>"Development tools" (selected during installation)</para></listitem>
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<listitem><para><filename>texi2html</filename></para></listitem>
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<listitem><para><filename>compat-gcc-34</filename></para></listitem>
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</itemizedlist>
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On top of these, you need the following external packages:
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<itemizedlist>
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<listitem><para><filename>python-sqlite2</filename> from
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<ulink url='http://dag.wieers.com/rpm/packages/python-sqlite2/'>DAG repository</ulink>
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</para></listitem>
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<listitem><para><filename>help2man</filename> from
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<ulink url='http://centos.karan.org/el5/extras/testing/i386/RPMS/help2man-1.33.1-2.noarch.rpm'>Karan repository</ulink></para></listitem>
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</itemizedlist>
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</para>
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<para>
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Once these packages are installed, the Yocto Project will be able to build standard
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images.
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However, there might be a problem with the QEMU emulator segfaulting.
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You can either disable the generation of binary locales by setting
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<filename><link linkend='var-ENABLE_BINARY_LOCALE_GENERATION'>ENABLE_BINARY_LOCALE_GENERATION</link>
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</filename> to "0" or by removing the <filename>linux-2.6-execshield.patch</filename>
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from the kernel and rebuilding it since that is the patch that causes the problems with QEMU.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I see lots of 404 responses for files on
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<filename>http://www.yoctoproject.org/sources/*</filename>. Is something wrong?
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</para>
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</question>
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<answer>
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<para>
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Nothing is wrong.
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The Yocto Project checks any configured source mirrors before downloading
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from the upstream sources.
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The Yocto Project does this searching for both source archives and
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pre-checked out versions of SCM managed software.
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These checks help in large installations because it can reduce load on the SCM servers
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themselves.
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The address above is one of the default mirrors configured into the
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Yocto Project.
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Consequently, if an upstream source disappears, the team
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can place sources there so builds continue to work.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I have machine-specific data in a package for one machine only but the package is
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being marked as machine-specific in all cases, how do I prevent this?
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</para>
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</question>
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<answer>
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<para>
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Set <filename><link linkend='var-SRC_URI_OVERRIDES_PACKAGE_ARCH'>SRC_URI_OVERRIDES_PACKAGE_ARCH</link>
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</filename> = "0" in the <filename>.bb</filename> file but make sure the package is
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manually marked as
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machine-specific in the case that needs it.
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The code that handles
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<filename><link linkend='var-SRC_URI_OVERRIDES_PACKAGE_ARCH'>
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SRC_URI_OVERRIDES_PACKAGE_ARCH</link></filename> is in <filename>base.bbclass</filename>.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I'm behind a firewall and need to use a proxy server. How do I do that?
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</para>
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</question>
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<answer>
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<para>
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Most source fetching by the Yocto Project is done by <filename>wget</filename>
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and you therefore need to specify the proxy settings in a
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<filename>.wgetrc</filename> file in your home directory.
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Example settings in that file would be
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<literallayout class='monospaced'>
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http_proxy = http://proxy.yoyodyne.com:18023/
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ftp_proxy = http://proxy.yoyodyne.com:18023/
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</literallayout>
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The Yocto Project also includes a <filename>site.conf.sample</filename>
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file that shows how to configure CVS and Git proxy servers
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if needed.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I'm using Ubuntu Intrepid and am seeing build failures. What’s wrong?
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</para>
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</question>
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<answer>
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<para>
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In Intrepid, Ubuntu turns on by default the normally optional compile-time security features
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and warnings.
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There are more details at
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<ulink url='https://wiki.ubuntu.com/CompilerFlags'>https://wiki.ubuntu.com/CompilerFlags</ulink>.
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You can work around this problem by disabling those options by adding
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the following to the <filename>BUILD_CPPFLAGS</filename> variable in the
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<filename>conf/bitbake.conf</filename> file.
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<literallayout class='monospaced'>
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" -Wno-format-security -U_FORTIFY_SOURCE"
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</literallayout>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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What’s the difference between <filename>foo</filename> and <filename>foo-native</filename>?
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</para>
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</question>
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<answer>
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<para>
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The <filename>*-native</filename> targets are designed to run on the system
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being used for the build.
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These are usually tools that are needed to assist the build in some way such as
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<filename>quilt-native</filename>, which is used to apply patches.
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The non-native version is the one that runs on the target device.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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I'm seeing random build failures. Help?!
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</para>
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</question>
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<answer>
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<para>
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If the same build is failing in totally different and random ways,
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the most likely explanation is that either the hardware you're running the
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build on has some problem, or, if you are running the build under virtualisation,
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the virtualisation probably has bugs.
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The Yocto Project processes a massive amount of data causing lots of network, disk and
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CPU activity and is sensitive to even single bit failures in any of these areas.
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True random failures have always been traced back to hardware or virtualisation issues.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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What do we need to ship for license compliance?
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</para>
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</question>
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<answer>
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<para>
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This is a difficult question and you need to consult your lawyer for the answer
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for your specific case.
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It is worth bearing in mind that for GPL compliance there needs to be enough
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information shipped to allow someone else to rebuild the same end result
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you are shipping.
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This means sharing the source code, any patches applied to it, and also any
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configuration information about how that package was configured and built.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I disable the cursor on my touchscreen device?
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</para>
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</question>
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<answer>
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<para>
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You need to create a form factor file as described in
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<xref linkend='bsp-filelayout-misc-recipes'>"Miscellaneous Recipe Files"</xref>
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and set the <filename>HAVE_TOUCHSCREEN</filename> variable equal to one as follows:
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<literallayout class='monospaced'>
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HAVE_TOUCHSCREEN=1
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</literallayout>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I make sure connected network interfaces are brought up by default?
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</para>
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</question>
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<answer>
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<para>
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The default interfaces file provided by the netbase recipe does not
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automatically bring up network interfaces.
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Therefore, you will need to add a BSP-specific netbase that includes an interfaces
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file.
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See <xref linkend='bsp-filelayout-misc-recipes'>"Miscellaneous Recipe Files"</xref>
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for information on creating these types of miscellaneous recipe files.
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</para>
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<para>
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For example, add the following files to your layer:
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<literallayout class='monospaced'>
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meta-MACHINE/recipes-bsp/netbase/netbase/MACHINE/interfaces
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meta-MACHINE/recipes-bsp/netbase/netbase_4.44.bbappend
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</literallayout>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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How do I create images with more free space?
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</para>
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</question>
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<answer>
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<para>
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Images are created to be 1.2 times the size of the populated root filesystem.
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To modify this ratio so that there is more free space available, you need to
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set the configuration value <filename>IMAGE_OVERHEAD_FACTOR</filename>.
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For example, setting <filename>IMAGE_OVERHEAD_FACTOR</filename> to 1.5 sets
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the image size ratio to one and a half times the size of the populated
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root filesystem.
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<literallayout class='monospaced'>
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IMAGE_OVERHEAD_FACTOR = "1.5"
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</literallayout>
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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<para>
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Why don't you support directories with spaces in the pathnames?
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</para>
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</question>
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<answer>
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<para>
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The Yocto Project team has tried to do this before but too many of the tools
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the Yocto Project depends on such as <filename>autoconf</filename>
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break when they find spaces in pathnames.
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Until that situation changes, the team will not support spaces in pathnames.
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</para>
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</answer>
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</qandaentry>
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<qandaentry>
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<question>
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||
<para>
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How do I use an external toolchain?
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</para>
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</question>
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<answer>
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<para>
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The toolchain configuration is very flexible and customizable.
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It is primarily controlled with the
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<filename><link linkend='var-TCMODE'>TCMODE</link></filename> variable.
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This variable controls which file to include
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(<filename>conf/distro/include/tcmode-*.inc</filename>).
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</para>
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<para>
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The default value of <filename>TCMODE</filename> is "default".
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However, other patterns are accepted.
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In particular, "external-*" refers to external toolchains of which there are some basic examples
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included with the core.
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A user can use their own custom toolchain definition in their own layer
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(or as defined in the <filename>local.conf</filename> file) at the location
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<filename>conf/distro/include/tcmode-*.inc</filename>.
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</para>
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<para>
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In addition to the toolchain configuration, you also need a corresponding toolchain recipe file.
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This recipe file needs to package up any pre-built objects in the toolchain such as
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<filename>libgcc</filename>, <filename>libstdcc++</filename>,
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any locales and <filename>libc</filename>.
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An example is the <filename>external-csl-toolchain_2008q3-72.bb</filename>, which reuses the core
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<filename>libc</filename> packaging class to do most of the work.
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</para>
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||
</answer>
|
||
</qandaentry>
|
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|
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<qandaentry>
|
||
<question>
|
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<para>
|
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How does the Yocto Project obtain source code and will it work behind my
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firewall or proxy server?
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</para>
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||
</question>
|
||
<answer>
|
||
<para>
|
||
The way the Yocto Project obtains source code is highly configurable.
|
||
You can setup the Yocto Project to get source code in most environments if
|
||
HTTP transport is available.
|
||
</para>
|
||
<para>
|
||
When the build system searches for source code, it first tries the local download directory.
|
||
If that location fails, Poky tries PREMIRRORS, the upstream source,
|
||
and then MIRRORS in that order.
|
||
</para>
|
||
<para>
|
||
By default, Poky uses the Yocto Project source PREMIRRORS for SCM-based sources,
|
||
upstreams for normal tarballs, and then falls back to a number of other mirrors
|
||
including the Yocto Project source mirror if those fail.
|
||
</para>
|
||
<para>
|
||
As an example, you could add a specific server for Poky to attempt before any
|
||
others by adding something like the following to the <filename>local.conf</filename>
|
||
configuration file:
|
||
<literallayout class='monospaced'>
|
||
PREMIRRORS_prepend = "\
|
||
git://.*/.* http://www.yoctoproject.org/sources/ \n \
|
||
ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
|
||
http://.*/.* http://www.yoctoproject.org/sources/ \n \
|
||
https://.*/.* http://www.yoctoproject.org/sources/ \n"
|
||
</literallayout>
|
||
</para>
|
||
<para>
|
||
These changes cause Poky to intercept Git, FTP, HTTP, and HTTPS
|
||
requests and direct them to the <filename>http://</filename> sources mirror.
|
||
You can use <filename>file://</filename> URLs to point to local directories
|
||
or network shares as well.
|
||
</para>
|
||
<para>
|
||
Aside from the previous technique, these options also exist:
|
||
<literallayout class='monospaced'>
|
||
BB_NO_NETWORK = "1"
|
||
</literallayout>
|
||
This statement tells BitBake to throw an error instead of trying to access the
|
||
Internet.
|
||
This technique is useful if you want to ensure code builds only from local sources.
|
||
</para>
|
||
<para>
|
||
Here is another technique:
|
||
<literallayout class='monospaced'>
|
||
BB_FETCH_PREMIRRORONLY = "1"
|
||
</literallayout>
|
||
This statement limits Poky to pulling source from the PREMIRRORS only.
|
||
Again, this technique is useful for reproducing builds.
|
||
</para>
|
||
<para>
|
||
Here is another technique:
|
||
<literallayout class='monospaced'>
|
||
BB_GENERATE_MIRROR_TARBALLS = "1"
|
||
</literallayout>
|
||
This statement tells Poky to generate mirror tarballs.
|
||
This technique is useful if you want to create a mirror server.
|
||
If not, however, the technique can simply waste time during the build.
|
||
</para>
|
||
<para>
|
||
Finally, consider an example where you are behind an HTTP-only firewall.
|
||
You could make the following changes to the <filename>local.conf</filename>
|
||
configuration file as long as the PREMIRROR server is up to date:
|
||
<literallayout class='monospaced'>
|
||
PREMIRRORS_prepend = "\
|
||
ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
|
||
http://.*/.* http://www.yoctoproject.org/sources/ \n \
|
||
https://.*/.* http://www.yoctoproject.org/sources/ \n"
|
||
BB_FETCH_PREMIRRORONLY = "1"
|
||
</literallayout>
|
||
These changes would cause Poky to successfully fetch source over HTTP and
|
||
any network accesses to anything other than the PREMIRROR would fail.
|
||
</para>
|
||
<para>
|
||
Poky also honors the standard environment variables
|
||
<filename>http_proxy</filename>, <filename>ftp_proxy</filename>,
|
||
<filename>https_proxy</filename>, and <filename>all_proxy</filename>
|
||
to redirect requests through proxy servers.
|
||
</para>
|
||
</answer>
|
||
</qandaentry>
|
||
</qandaset>
|
||
</appendix>
|
||
<!--
|
||
vim: expandtab tw=80 ts=4
|
||
-->
|
||
|