Re: perf-probe : error "Rebuild with -g, or install an appropriate debuginfo package"

[HOUSSEN Franck <fghoussen@gmail.com>]

Installing dwarf was the solution. Now, compiling with either -g or
-ggdb, I can probe the function.

Thanks !

Franck

2016-12-01 6:26 GMT+01:00 Masami Hiramatsu <mhiramat@kernel.org>:
> On Wed, 30 Nov 2016 14:49:09 +0100
> HOUSSEN Franck <fghoussen@gmail.com> wrote:
>
>> I compiled myApp.cpp (that contains a function named myFunction) with:
>> ~>mpic++ -O2 -ggdb -fno-omit-frame-pointer -o myApp myApp.cpp
>>
>> When I try to probe a function from the myApp binary, I get:
>> ~> sudo perf probe --exe ./myApp --add "myFunction:2"
>> The /home/path/to/myApp file has no debug information.
>> Rebuild with -g, or install an appropriate debuginfo package.
>>   Error: Failed to add events.
>
> Could you run `eu-readelf -S myApp` ?
> Could you also try to build your app with '-g' instead of '-ggdb'?
> I guess mpic++ might generate some extened debuginfo or just ignored
> the option.
>
>>
>> ... -g has been set a t compile time and libelf (and libelf-dev) seems
>> to be installed:
>
> No, libelf is not related to this issue.
>
> [...]
>> PS : When I do that
>> ~>sudo perf probe --exe ./myApp --add "myFunction"
>> Added new event:
>>   probe_myApp:myFunction (on myFunction in /home/path/to/myApp)
>>
>> It works !?... I need to place the tracepoint at the second line below
>> the entry of myFunction => replacing "myFunction" with "myFunction:2"
>> does not work ! Why ?...
>
> Without line number, perf probe tries to find symbols from symtab in
> the binary. DWARF (a.k.a. debuginfo) has much more information, like
> line-to-addr, local variable assignment etc.
>
> Thanks,
>
>
> --
> Masami Hiramatsu <mhiramat@kernel.org>



-- 
Bonne journée,

Franck HOUSSEN