Crash Feature to print dwarf debugging information

Petr Machata pmachata at redhat.com
Thu Mar 12 15:07:56 UTC 2009


Sharyathi Nagesh wrote:
> I looked into libdwfl.h, which is used by systemtap, as I understand 
> this will be useful in debugging running machine and not the case I 
> am looking for so I am considering only libdw.h for the time being.

libdwfl can be useful also for post-mortem debugging. It manages address 
space, i.e. knows which module is mapped to which address, and has a 
couple useful features that are related to that. It understands that 
debuginfo portion of the module can be stored separately from the main 
ELF file, and supports build ID for debuginfo file lookup.  It knows 
about bias (the difference between where the library gets mapped, and 
what's its base address as noted in the ELF file; important e.g. when 
translating symbol table addresses to address space addresses). I think 
it can do some limited REL file relocation (so that you can map kernel 
modules into the address space). So it's basically a library of things 
you would have to implement anyway, I think.

I'm not too familiar with libdwfl myself, so if what I've written above 
seems vague, that's because it is ;)

Anyway, hope that helps.
PM

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