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authorScott Rifenbark <scott.m.rifenbark@intel.com>2014-08-01 12:06:37 +0300
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-08-02 10:00:26 +0100
commite7dae57a98e4ce3fa86a3dfdfe1f0c21a463d638 (patch)
tree6e9e7b2f0b8e776aea9e4a5ab865ae6981a907d1 /documentation/ref-manual/faq.xml
parent152d30776756d22c07d88bddbb6d112305b99c0e (diff)
downloadpoky-e7dae57a98e4ce3fa86a3dfdfe1f0c21a463d638.tar.gz
ref-manual: Added two new FAQ entries.
One has to do with the weird names the build system creates based on DESTDIR and other variables. The other has to do with -native recipes not buiding correctly. (From yocto-docs rev: 32a444a258e3c7c87fdc015475f54e5b34628246) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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@@ -682,6 +682,112 @@
682 </answer> 682 </answer>
683 </qandaentry> 683 </qandaentry>
684 684
685 <qandaentry>
686 <question>
687 <para>
688 Why do <filename>${bindir}</filename> and <filename>${libdir}</filename> have strange values for <filename>-native</filename> recipes?
689 </para>
690 </question>
691 <answer>
692 <para>
693 Executables and libraries might need to be used from a
694 directory other than the directory into which they were
695 initially installed.
696 Complicating this situation is the fact that sometimes these
697 executables and libraries are compiled with the expectation
698 of being run from that initial installation target directory.
699 If this is the case, moving them causes problems.
700 </para>
701
702 <para>
703 This scenario is a fundamental problem for package maintainers
704 of mainstream Linux distributions as well as for the
705 OpenEmbedded build system.
706 As such, a well-established solution exists.
707 Makefiles, Autotools configuration scripts, and other build
708 systems are expected to respect environment variables such as
709 <filename>bindir</filename>, <filename>libdir</filename>,
710 and <filename>sysconfdir</filename> that indicate where
711 executables, libraries, and data reside when a program is
712 actually run.
713 And, they are also expected to respect a
714 <filename>DESTDIR</filename> environment variable, which is
715 prepended to all the other variables when the build system
716 actually installs the files.
717 It is understood that the program does not actually run from
718 within <filename>DESTDIR</filename>.
719 </para>
720
721 <para>
722 When the OpenEmbedded build system uses a recipe to build a
723 target-architecture program (i.e. one that is intended for
724 inclusion on the image being built), that program eventually
725 runs from the root file system of that image.
726 Thus, the build system provides a value of "/usr/bin" for
727 <filename>bindir</filename>, a value of "/usr/lib" for
728 <filename>libdir</filename>, and so forth.
729 </para>
730
731 <para>
732 Meanwhile, <filename>DESTDIR</filename> is a path within the
733 <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>.
734 However, when the recipe builds a native program (i.e. one
735 that is intended to run on the build machine), that program
736 is never installed directly to the build machine's root
737 file system.
738 Consequently, the build system uses paths within the Build
739 Directory for <filename>DESTDIR</filename>,
740 <filename>bindir</filename> and related variables.
741 To better understand this, consider the following two paths
742 where the first is relatively normal and the second is not:
743 <note>
744 Due to these lengthy examples, the paths are artificially
745 broke across lines for readability.
746 </note>
747 <literallayout class='monospaced'>
748 /home/maxtothemax/poky-bootchart2/build/tmp/work/i586-poky-linux/zlib/
749 1.2.8-r0/sysroot-destdir/usr/bin
750
751 /home/maxtothemax/poky-bootchart2/build/tmp/work/x86_64-linux/
752 zlib-native/1.2.8-r0/sysroot-destdir/home/maxtothemax/poky-bootchart2/
753 build/tmp/sysroots/x86_64-linux/usr/bin
754 </literallayout>
755 The standard <filename>DESTDIR</filename> mechanism leaves no
756 other choice.
757 </para>
758 </answer>
759 </qandaentry>
760
761 <qandaentry>
762 <question>
763 <para>
764 The files provided by my <filename>-native</filename> recipe do
765 not appear to be available to other recipes.
766 Files are missing from the native sysroot, my recipe is
767 installing to the wrong place, or I am getting permissions
768 errors during the do_install task in my recipe! What is wrong?
769 </para>
770 </question>
771 <answer>
772 <para>
773 This situation results when the OpenEmbedded build system does
774 not recognize the environment variables supplied to it by
775 <ulink url='&YOCTO_DOCS_DEV_URL;#bitbake-term'>BitBake</ulink>.
776 The incident that prompted this FAQ entry involved a Makefile
777 that used an environment variable named
778 <filename>BINDIR</filename> instead of the more standard
779 variable <filename>bindir</filename>.
780 The makefile's hardcoded default value of "/usr/bin" worked
781 most of the time, but not for the recipe's
782 <filename>-native</filename> variant.
783 Consequently, permissions errors might be caused by a Makefile
784 that ignores <filename>DESTDIR</filename> or uses a different
785 name for that environment variable.
786 Check the OpenEmbedded build system to see if these kinds of
787 issues exist.
788 </para>
789 </answer>
790 </qandaentry>
685 791
686</qandaset> 792</qandaset>
687</chapter> 793</chapter>