** Description changed: + == Precise SRU Justification == + + Impact: When using systemtap with Ubuntu kernels, the proper debug + modules cannot be automatically discovered. + + == Fix == + + This fix allows for the build system to insert the .gnu_debuglink + sections in the .ko files pointing to the full unstripped .ko in + /usr/lib/debug/.. in the dbgsym ddebs. In addition there are checks to + ensure the debug symbol actually exists before creating the + .gnu_debuglink section. + + == Testcase == + + 1) Install systemtap. + 2) Run "stap -l 'module("serio_raw").function("*")'" + 3) This should show list all the probe points for that module. + + -- + Binary package hint: systemtap Even if the proper debug symbols are installed: # stap -l 'kernel.function("acpi_*")' | sort will succeed and this will fail. # stap -l 'module("ohci1394").function("*")' | sort Now there's no shortage of blogs and wikis on how to work around this but no one has seemingly ever investigated the root cause. If one were to run this through strace you would find the following. open("/usr/lib/debug/.build-id/3b/6eb5a0f22ba2bc92c3c3f1fcb14fe7f31f3807.debug", O_RDONLY) = -1 ENOENT (No such file or directory) open("/lib/modules/2.6.32-25-generic/kernel/drivers/ieee1394/ohci1394.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) open("/lib/modules/2.6.32-25-generic/kernel/drivers/ieee1394/.debug/ohci1394.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) open("/usr/lib/debug/lib/modules/2.6.32-25-generic/kernel/drivers/ieee1394/ohci1394.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) open("/lib/modules/2.6.32-25-generic/kernel/drivers/ieee1394/build/ohci1394.ko.debug", O_RDONLY) = -1 ENOENT (No such file or directory) Note that the path is correct, it's the name of the KO that stap is expecting that is wrong, Kernel debug symbols provided by Ubuntu are unstripped yet maintain the .ko extension, systemtap (actually libelf/elfutils) is expecting the filename to be module.ko.debug. After discussing this on #systemtap on Freenode, the following script was proposed to generate a symlink tree, by build id, in /usr/lib/debug, with the proper extension. This completely solves the issue, and is also of benefit to things like gdb and oprofile. #!/bin/sh for file in `find /usr/lib/debug -name '*.ko' -print` do - buildid=`eu-readelf -n $file| grep Build.ID: | awk '{print $3}'` - dir=`echo $buildid | cut -c1-2` - fn=`echo $buildid | cut -c3-` - mkdir -p /usr/lib/debug/.build-id/$dir - ln -s $file /usr/lib/debug/.build-id/$dir/$fn - ln -s $file /usr/lib/debug/.build-id/$dir/${fn}.debug + buildid=`eu-readelf -n $file| grep Build.ID: | awk '{print $3}'` + dir=`echo $buildid | cut -c1-2` + fn=`echo $buildid | cut -c3-` + mkdir -p /usr/lib/debug/.build-id/$dir + ln -s $file /usr/lib/debug/.build-id/$dir/$fn + ln -s $file /usr/lib/debug/.build-id/$dir/${fn}.debug done If we could integrate this into the ddeb postinstall script, the problem would be solved.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/669641 Title: systemtap fails to discover installed debug modules To manage notifications about this bug go to: https://bugs.launchpad.net/linaro-ubuntu/+bug/669641/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs