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authorScott Rifenbark <scott.m.rifenbark@intel.com>2012-12-11 12:07:58 -0600
committerRichard Purdie <richard.purdie@linuxfoundation.org>2013-01-07 14:43:25 +0000
commited0a240e1632682ec4c33341f3e24ad71773cdfc (patch)
tree201557f498b77b9f51fad7e12a6009f74aca4c65 /documentation/ref-manual/faq.xml
parentaf19d889ef320f9625aae42eed6688b5cc739793 (diff)
downloadast2050-yocto-poky-ed0a240e1632682ec4c33341f3e24ad71773cdfc.zip
ast2050-yocto-poky-ed0a240e1632682ec4c33341f3e24ad71773cdfc.tar.gz
documentation: Rename of poky-ref-manual folder to ref-manual.
Changing the folder that holds the YP Reference Manual to be "ref-manual". This will help with confustion over the manual's intended purpose. (From yocto-docs rev: 1106442964b5080cb0b6b3bd3af32e9407c0f7c1) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<chapter id='faq'>
+<title>FAQ</title>
+<qandaset>
+ <qandaentry>
+ <question>
+ <para>
+ How does Poky differ from <ulink url='&OE_HOME_URL;'>OpenEmbedded</ulink>?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The term "Poky" refers to the specific reference build system that
+ the Yocto Project provides.
+ Poky is based on <ulink url='&YOCTO_DOCS_DEV_URL;#oe-core'>OE-Core</ulink>
+ and BitBake.
+ Thus, the generic term used here for the build system is
+ the "OpenEmbedded build system."
+ Development in the Yocto Project using Poky is closely tied to OpenEmbedded, with
+ changes always being merged to OE-Core or BitBake first before being pulled back
+ into Poky.
+ This practice benefits both projects immediately.
+ For a fuller description of the term "Poky", see the
+ <ulink url='&YOCTO_DOCS_DEV_URL;#poky'>poky</ulink> term in the Yocto Project
+ Development Manual.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I only have Python 2.4 or 2.5 but BitBake requires Python 2.6 or 2.7.
+ Can I still use the Yocto Project?
+ </para>
+ </question>
+ <answer>
+ <para>
+ You can use a stand-alone tarball to provide Python 2.6.
+ You can find pre-built 32 and 64-bit versions of Python 2.6 at the following locations:
+ <itemizedlist>
+ <listitem><para><ulink url='&YOCTO_PYTHON-i686_DL_URL;'>32-bit tarball</ulink></para></listitem>
+ <listitem><para><ulink url='&YOCTO_PYTHON-x86_64_DL_URL;'>64-bit tarball</ulink></para></listitem>
+ </itemizedlist>
+ </para>
+ <para>
+ These tarballs are self-contained with all required libraries and should work
+ on most Linux systems.
+ To use the tarballs extract them into the root
+ directory and run the appropriate command:
+ <literallayout class='monospaced'>
+ $ export PATH=/opt/poky/sysroots/i586-pokysdk-linux/usr/bin/:$PATH
+ $ export PATH=/opt/poky/sysroots/x86_64-pokysdk-linux/usr/bin/:$PATH
+ </literallayout>
+ </para>
+ <para>
+ Once you run the command, BitBake uses Python 2.6.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How can you claim Poky / OpenEmbedded-Core is stable?
+ </para>
+ </question>
+ <answer>
+ <para>
+ There are three areas that help with stability;
+ <itemizedlist>
+ <listitem><para>The Yocto Project team keeps
+ <ulink url='&YOCTO_DOCS_DEV_URL;#oe-core'>OE-Core</ulink> small
+ and focused, containing around 830 recipes as opposed to the thousands
+ available in other OpenEmbedded community layers.
+ Keeping it small makes it easy to test and maintain.</para></listitem>
+ <listitem><para>The Yocto Project team runs manual and automated tests
+ using a small, fixed set of reference hardware as well as emulated
+ targets.</para></listitem>
+ <listitem><para>The Yocto Project uses an an autobuilder,
+ which provides continuous build and integration tests.</para></listitem>
+ </itemizedlist>
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I get support for my board added to the Yocto Project?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Support for an additional board is added by creating a BSP layer for it.
+ For more information on how to create a BSP layer, see the
+ <ulink url='&YOCTO_DOCS_BSP_URL;'>Yocto Project Board Support Package (BSP) Developer's Guide</ulink>.
+ </para>
+ <para>
+ Usually, if the board is not completely exotic, adding support in
+ the Yocto Project is fairly straightforward.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ Are there any products built using the OpenEmbedded build system?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The software running on the <ulink url='http://vernier.com/labquest/'>Vernier LabQuest</ulink>
+ is built using the OpenEmbedded build system.
+ See the <ulink url='http://www.vernier.com/products/interfaces/labq/'>Vernier LabQuest</ulink>
+ website for more information.
+ There are a number of pre-production devices using the OpenEmbedded build system
+ and the Yocto Project team
+ announces them as soon as they are released.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ What does the OpenEmbedded build system produce as output?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Because the same set of recipes can be used to create output of various formats, the
+ output of an OpenEmbedded build depends on how it was started.
+ Usually, the output is a flashable image ready for the target device.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I add my package to the Yocto Project?
+ </para>
+ </question>
+ <answer>
+ <para>
+ To add a package, you need to create a BitBake recipe.
+ For information on how to add a package, see the section
+ "<ulink url='&YOCTO_DOCS_DEV_URL;#usingpoky-extend-addpkg'>Adding a Package</ulink>"
+ in the Yocto Project Development Manual.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ Do I have to reflash my entire board with a new Yocto Project image when recompiling
+ a package?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The OpenEmbedded build system can build packages in various formats such as
+ <filename>ipk</filename> for <filename>opkg</filename>,
+ Debian package (<filename>.deb</filename>), or RPM.
+ The packages can then be upgraded using the package tools on the device, much like
+ on a desktop distribution such as Ubuntu or Fedora.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ What is GNOME Mobile and what is the difference between GNOME Mobile and GNOME?
+ </para>
+ </question>
+ <answer>
+ <para>
+ GNOME Mobile is a subset of the <ulink url='http://www.gnome.org'>GNOME</ulink>
+ platform targeted at mobile and embedded devices.
+ The the main difference between GNOME Mobile and standard GNOME is that
+ desktop-orientated libraries have been removed, along with deprecated libraries,
+ creating a much smaller footprint.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I see the error '<filename>chmod: XXXXX new permissions are r-xrwxrwx, not r-xr-xr-x</filename>'.
+ What is wrong?
+ </para>
+ </question>
+ <answer>
+ <para>
+ You are probably running the build on an NTFS filesystem.
+ Use <filename>ext2</filename>, <filename>ext3</filename>, or <filename>ext4</filename> instead.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I make the Yocto Project work in RHEL/CentOS?
+ </para>
+ </question>
+ <answer>
+ <para>
+ To get the Yocto Project working under RHEL/CentOS 5.1 you need to first
+ install some required packages.
+ The standard CentOS packages needed are:
+ <itemizedlist>
+ <listitem><para>"Development tools" (selected during installation)</para></listitem>
+ <listitem><para><filename>texi2html</filename></para></listitem>
+ <listitem><para><filename>compat-gcc-34</filename></para></listitem>
+ </itemizedlist>
+ On top of these, you need the following external packages:
+ <itemizedlist>
+ <listitem><para><filename>python-sqlite2</filename> from
+ <ulink url='http://dag.wieers.com/rpm/packages/python-sqlite2/'>DAG repository</ulink>
+ </para></listitem>
+ <listitem><para><filename>help2man</filename> from
+ <ulink url='http://centos.karan.org/el4/extras/stable/x86_64/RPMS/repodata/repoview/help2man-0-1.33.1-2.html'>Karan repository</ulink></para></listitem>
+ </itemizedlist>
+ </para>
+
+ <para>
+ Once these packages are installed, the OpenEmbedded build system will be able
+ to build standard images.
+ However, there might be a problem with the QEMU emulator segfaulting.
+ You can either disable the generation of binary locales by setting
+ <filename><link linkend='var-ENABLE_BINARY_LOCALE_GENERATION'>ENABLE_BINARY_LOCALE_GENERATION</link>
+ </filename> to "0" or by removing the <filename>linux-2.6-execshield.patch</filename>
+ from the kernel and rebuilding it since that is the patch that causes the problems with QEMU.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I see lots of 404 responses for files on
+ <filename>http://www.yoctoproject.org/sources/*</filename>. Is something wrong?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Nothing is wrong.
+ The OpenEmbedded build system checks any configured source mirrors before downloading
+ from the upstream sources.
+ The build system does this searching for both source archives and
+ pre-checked out versions of SCM managed software.
+ These checks help in large installations because it can reduce load on the SCM servers
+ themselves.
+ The address above is one of the default mirrors configured into the
+ build system.
+ Consequently, if an upstream source disappears, the team
+ can place sources there so builds continue to work.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I have machine-specific data in a package for one machine only but the package is
+ being marked as machine-specific in all cases, how do I prevent this?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Set <filename><link linkend='var-SRC_URI_OVERRIDES_PACKAGE_ARCH'>SRC_URI_OVERRIDES_PACKAGE_ARCH</link>
+ </filename> = "0" in the <filename>.bb</filename> file but make sure the package is
+ manually marked as
+ machine-specific in the case that needs it.
+ The code that handles <filename>SRC_URI_OVERRIDES_PACKAGE_ARCH</filename> is in <filename>base.bbclass</filename>.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I'm behind a firewall and need to use a proxy server. How do I do that?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Most source fetching by the OpenEmbedded build system is done by <filename>wget</filename>
+ and you therefore need to specify the proxy settings in a
+ <filename>.wgetrc</filename> file in your home directory.
+ Example settings in that file would be
+ <literallayout class='monospaced'>
+ http_proxy = http://proxy.yoyodyne.com:18023/
+ ftp_proxy = http://proxy.yoyodyne.com:18023/
+ </literallayout>
+ The Yocto Project also includes a <filename>site.conf.sample</filename>
+ file that shows how to configure CVS and Git proxy servers
+ if needed.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ What’s the difference between <filename>foo</filename> and <filename>foo-native</filename>?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The <filename>*-native</filename> targets are designed to run on the system
+ being used for the build.
+ These are usually tools that are needed to assist the build in some way such as
+ <filename>quilt-native</filename>, which is used to apply patches.
+ The non-native version is the one that runs on the target device.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ I'm seeing random build failures. Help?!
+ </para>
+ </question>
+ <answer>
+ <para>
+ If the same build is failing in totally different and random ways,
+ the most likely explanation is that either the hardware you're running the
+ build on has some problem, or, if you are running the build under virtualisation,
+ the virtualisation probably has bugs.
+ The OpenEmbedded build system processes a massive amount of data causing lots of network, disk and
+ CPU activity and is sensitive to even single bit failures in any of these areas.
+ True random failures have always been traced back to hardware or virtualisation issues.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ What do we need to ship for license compliance?
+ </para>
+ </question>
+ <answer>
+ <para>
+ This is a difficult question and you need to consult your lawyer for the answer
+ for your specific case.
+ It is worth bearing in mind that for GPL compliance there needs to be enough
+ information shipped to allow someone else to rebuild the same end result
+ you are shipping.
+ This means sharing the source code, any patches applied to it, and also any
+ configuration information about how that package was configured and built.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I disable the cursor on my touchscreen device?
+ </para>
+ </question>
+ <answer>
+ <para>
+ You need to create a form factor file as described in the
+ "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-misc-recipes'>Miscellaneous Recipe Files</ulink>"
+ section and set the <filename>HAVE_TOUCHSCREEN</filename> variable equal to one as follows:
+ <literallayout class='monospaced'>
+ HAVE_TOUCHSCREEN=1
+ </literallayout>
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I make sure connected network interfaces are brought up by default?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The default interfaces file provided by the netbase recipe does not
+ automatically bring up network interfaces.
+ Therefore, you will need to add a BSP-specific netbase that includes an interfaces
+ file.
+ See the "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-misc-recipes'>Miscellaneous Recipe Files</ulink>"
+ section for information on creating these types of miscellaneous recipe files.
+ </para>
+ <para>
+ For example, add the following files to your layer:
+ <literallayout class='monospaced'>
+ meta-MACHINE/recipes-bsp/netbase/netbase/MACHINE/interfaces
+ meta-MACHINE/recipes-bsp/netbase/netbase_5.0.bbappend
+ </literallayout>
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I create images with more free space?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Images are created to be 1.2 times the size of the populated root filesystem.
+ To modify this ratio so that there is more free space available, you need to
+ set the configuration value <filename>IMAGE_OVERHEAD_FACTOR</filename>.
+ For example, setting <filename>IMAGE_OVERHEAD_FACTOR</filename> to 1.5 sets
+ the image size ratio to one and a half times the size of the populated
+ root filesystem.
+ <literallayout class='monospaced'>
+ IMAGE_OVERHEAD_FACTOR = "1.5"
+ </literallayout>
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ Why don't you support directories with spaces in the pathnames?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The Yocto Project team has tried to do this before but too many of the tools
+ the OpenEmbedded build system depends on such as <filename>autoconf</filename>
+ break when they find spaces in pathnames.
+ Until that situation changes, the team will not support spaces in pathnames.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para>
+ How do I use an external toolchain?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The toolchain configuration is very flexible and customizable.
+ It is primarily controlled with the
+ <filename><link linkend='var-TCMODE'>TCMODE</link></filename> variable.
+ This variable controls which <filename>tcmode-*.inc</filename> file to include
+ from the <filename>meta/conf/distro/include</filename> directory within the
+ <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>source directory</ulink>.
+ </para>
+
+ <para>
+ The default value of <filename>TCMODE</filename> is "default"
+ (i.e. <filename>tcmode-default.inc</filename>).
+ However, other patterns are accepted.
+ In particular, "external-*" refers to external toolchains of which there are some
+ basic examples included in the OpenEmbedded Core (<filename>meta</filename>).
+ You can use your own custom toolchain definition in your own layer
+ (or as defined in the <filename>local.conf</filename> file) at the location
+ <filename>conf/distro/include/tcmode-*.inc</filename>.
+ </para>
+
+ <para>
+ In addition to the toolchain configuration, you also need a corresponding toolchain recipe file.
+ This recipe file needs to package up any pre-built objects in the toolchain such as
+ <filename>libgcc</filename>, <filename>libstdcc++</filename>,
+ any locales, and <filename>libc</filename>.
+ An example is the <filename>external-sourcery-toolchain.bb</filename>, which is located
+ in <filename>meta/recipes-core/meta/</filename> within the source directory.
+ </para>
+ </answer>
+ </qandaentry>
+
+ <qandaentry>
+ <question>
+ <para id='how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server'>
+ How does the OpenEmbedded build system obtain source code and will it work behind my
+ firewall or proxy server?
+ </para>
+ </question>
+ <answer>
+ <para>
+ The way the build system obtains source code is highly configurable.
+ You can setup the build system 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, the OpenEmbedded build system 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>
+ The build system also honors the standard shell 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>
+
+ <qandaentry>
+ <question>
+ <para>
+ Can I get rid of build output so I can start over?
+ </para>
+ </question>
+ <answer>
+ <para>
+ Yes - you can easily do this.
+ When you use BitBake to build an image, all the build output goes into the
+ directory created when you source the <filename>oe-init-build-env</filename>
+ setup file.
+ By default, this <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>build directory</ulink>
+ is named <filename>build</filename> but can be named
+ anything you want.
+ </para>
+
+ <para>
+ Within the build directory is the <filename>tmp</filename> directory.
+ To remove all the build output yet preserve any source code or downloaded files
+ from previous builds, simply remove the <filename>tmp</filename> directory.
+ </para>
+ </answer>
+ </qandaentry>
+
+
+</qandaset>
+</chapter>
+<!--
+vim: expandtab tw=80 ts=4
+-->
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