Re: [RFC] elfutils: Checks for debuginfo file without .debug extension as well

[Mark Wielaard <mjw at redhat dot com>]

Hi Ravi,

On Tue, 2016-02-16 at 21:51 +0530, Ravi Bangoria wrote:
> Elfutils, looking for kernel debuginfo file, tries to find it at
> various places. If elfutils finds /boot/vmlinu*x* file, it checks
> for debufginfo section. If debuginfo is not present, it saves it as
> 'main elf' and continue looking for debuginfo file having .debug
> extension i.e. vmlinux-RELEASE.debug.
> 
> 'Ubuntu on powerpc' installs kernel as /boot/vmlinux and installs
> debuginfo without any extension as /usr/lib/debug/boot/vmlinux-RELEASE
> and hence, elfutils is not able to find the debuginfo file.
> 
> Here is the lunchpad bug for the same:
>   https://bugs.launchpad.net/ubuntu/+source/systemtap/+bug/1537125
> 
> This patch adds functionality to search for file without any extension
> followed by searching file having .debug extension.

Thanks for the analysis. I do have a question though.

The reason we are looking for the vmlinux-3.13.0-76-generic.debug
filename instead of the plain vmlinux-3.13.0-76-generic filename seems
to be because /boot/vmlinux contains a .gnu_debuginfo link with the name
of the debug file. But that name doesn't match?

What does eu-readelf --strings=.gnu_debuglink /boot/vmlinux* say?

Would it make sense to not put in the "correct" (without .debug suffix)
debugfile name in .gnu_debuglink or completely leaving .gnu_debuginfo
out (or is nothing found then?)

Thanks,

Mark