Re: Re: [PATCH] perf probe: Warn user to rebuild target with debuginfo

[Masami Hiramatsu]

(2014/08/15 10:07), Arnaldo Carvalho de Melo wrote:
> Em Thu, Aug 14, 2014 at 01:07:28PM -0700, Brendan Gregg escreveu:
>> On Thu, Aug 14, 2014 at 11:29 AM, Masami Hiramatsu
>> <masami.hiramatsu.pt@xxxxxxxxxxx> wrote:
>> [...]
>>> The "rebuild with ..." part changes to "rebuild with CONFIG_DEBUG_INFO"
>>> if the target is the kernel or a kernel module.
>  
>> Thanks, definitely an improvement! Should the kernel message also
>> mention kernel debuginfo packages? Depends on the distribution and
>> environment, but I think for some users the solution is to add the
>> package.

I see, and at least fedora/rhel has debuginfo for all packages.
So, not only for the kernel, but also for user applications,
we'll need to do that.

> Yeah, something like what is suggested by gdb and documented here:
> 
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Developer_Guide/intro.debuginfo.html
> 
> --------------------------------------------------------------------
> In some cases (such as loading a core file), GDB does not know the
> name, version, or release of a name-debuginfo-version-release.rpm
> package; it only knows the build-id. In such cases, GDB suggests a
> different command:
> 
> gdb -c ./core
> [...]
> Missing separate debuginfo for the main executable filename
> Try: yum --disablerepo='*' --enablerepo='*debug*' install /usr/lib/debug/.build-id/ef/dd0b5e69b0742fa5e5bad0771df4d1df2459d1
> ---------------------------------------------------------------------

ah, that's nice :)

> 
> This is something I want to have eventually, i.e. to have per distro
> plugins to automatically download packages required for some features,
> like probing and annotation, for instance.

Yeah, however, it depends on the distro. AFAIK, ubuntu provides
debuginfo package only for the kernel. So, at this point, I think
what we can do is just say "please install debuginfo package"
as below.

  $ ./perf probe -x perf -L argv_split
  The /home/fedora/ksrc/linux-3/tools/perf/perf file has no debug information, rebuild with -g.
  Or install appropriate debuginfo package.
    Error: Failed to show lines.

Thank you,

-- 
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Research Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx


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