diff options
Diffstat (limited to 'documentation/ref-manual/faq.xml')
| -rw-r--r-- | documentation/ref-manual/faq.xml | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/documentation/ref-manual/faq.xml b/documentation/ref-manual/faq.xml index bc147ce70a..72ff0d6fda 100644 --- a/documentation/ref-manual/faq.xml +++ b/documentation/ref-manual/faq.xml @@ -682,6 +682,112 @@ </answer> </qandaentry> + <qandaentry> + <question> + <para> + Why do <filename>${bindir}</filename> and <filename>${libdir}</filename> have strange values for <filename>-native</filename> recipes? + </para> + </question> + <answer> + <para> + Executables and libraries might need to be used from a + directory other than the directory into which they were + initially installed. + Complicating this situation is the fact that sometimes these + executables and libraries are compiled with the expectation + of being run from that initial installation target directory. + If this is the case, moving them causes problems. + </para> + + <para> + This scenario is a fundamental problem for package maintainers + of mainstream Linux distributions as well as for the + OpenEmbedded build system. + As such, a well-established solution exists. + Makefiles, Autotools configuration scripts, and other build + systems are expected to respect environment variables such as + <filename>bindir</filename>, <filename>libdir</filename>, + and <filename>sysconfdir</filename> that indicate where + executables, libraries, and data reside when a program is + actually run. + And, they are also expected to respect a + <filename>DESTDIR</filename> environment variable, which is + prepended to all the other variables when the build system + actually installs the files. + It is understood that the program does not actually run from + within <filename>DESTDIR</filename>. + </para> + + <para> + When the OpenEmbedded build system uses a recipe to build a + target-architecture program (i.e. one that is intended for + inclusion on the image being built), that program eventually + runs from the root file system of that image. + Thus, the build system provides a value of "/usr/bin" for + <filename>bindir</filename>, a value of "/usr/lib" for + <filename>libdir</filename>, and so forth. + </para> + + <para> + Meanwhile, <filename>DESTDIR</filename> is a path within the + <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>Build Directory</ulink>. + However, when the recipe builds a native program (i.e. one + that is intended to run on the build machine), that program + is never installed directly to the build machine's root + file system. + Consequently, the build system uses paths within the Build + Directory for <filename>DESTDIR</filename>, + <filename>bindir</filename> and related variables. + To better understand this, consider the following two paths + where the first is relatively normal and the second is not: + <note> + Due to these lengthy examples, the paths are artificially + broke across lines for readability. + </note> + <literallayout class='monospaced'> + /home/maxtothemax/poky-bootchart2/build/tmp/work/i586-poky-linux/zlib/ + 1.2.8-r0/sysroot-destdir/usr/bin + + /home/maxtothemax/poky-bootchart2/build/tmp/work/x86_64-linux/ + zlib-native/1.2.8-r0/sysroot-destdir/home/maxtothemax/poky-bootchart2/ + build/tmp/sysroots/x86_64-linux/usr/bin + </literallayout> + The standard <filename>DESTDIR</filename> mechanism leaves no + other choice. + </para> + </answer> + </qandaentry> + + <qandaentry> + <question> + <para> + The files provided by my <filename>-native</filename> recipe do + not appear to be available to other recipes. + Files are missing from the native sysroot, my recipe is + installing to the wrong place, or I am getting permissions + errors during the do_install task in my recipe! What is wrong? + </para> + </question> + <answer> + <para> + This situation results when the OpenEmbedded build system does + not recognize the environment variables supplied to it by + <ulink url='&YOCTO_DOCS_DEV_URL;#bitbake-term'>BitBake</ulink>. + The incident that prompted this FAQ entry involved a Makefile + that used an environment variable named + <filename>BINDIR</filename> instead of the more standard + variable <filename>bindir</filename>. + The makefile's hardcoded default value of "/usr/bin" worked + most of the time, but not for the recipe's + <filename>-native</filename> variant. + Consequently, permissions errors might be caused by a Makefile + that ignores <filename>DESTDIR</filename> or uses a different + name for that environment variable. + Check the OpenEmbedded build system to see if these kinds of + issues exist. + </para> + </answer> + </qandaentry> </qandaset> </chapter> |