dwfl_attach_state alternative taking Ebl?

Ulf Hermann ulf.hermann@qt.io
Tue Apr 11 12:28:00 GMT 2017

> /* [...] Architecture of DWFL
>    modules is specified by ELF, ELF must remain valid during DWFL lifetime.
>    Use NULL ELF to detect architecture from DWFL, the function will then detect
>    it from arbitrary Dwfl_Module of DWFL.  [...]  */
> So would that be an alternative for you? How do you create the Dwfl? Do
> you add modules to it (how?) and when do you need to call
> dwfl_attach_state?

This is what we do. We parse perf.data. perf.data may contain 
information about file mappings at any point, and it may take a while 
until the first valid one shows up. So we postpone dwfl_attach_state 
until we have a mapping we can resolve to a local elf file.

The code would be cleaner if we could attach_state before starting to 
parse. And there might be pathological cases where no valid elf file can 
ever be found but we can still unwind by frame pointer.


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