Re: [PATCH 2/4] Add Jeff Mahoney's py-crash patches.

[Doug Evans <dje@google.com>]

On Wed, Feb 3, 2016 at 9:55 AM, Jeff Mahoney <jeffm@suse.com> wrote:
>...
>>> Hi.
>>
>> Hi Doug -
>>
>>> Part of what this patch is doing is exporting bfd to python.
>>> E.g., all the SEC_* constants.
>>
>>> As a rule we absolutely discourage people from using bfd outside
>>> of the the binutils+gdb source tree. Either this rule needs to
>>> change, or I don't think we can allow this patch. I'd be
>>> interested to hear what others in the community think.
>>
>> That's unfortunate.  The Linux kernel uses ELF sections for a
>> number of purposes.  Most notably is the definition of per-cpu
>> variables. Without the ELF section, we can't resolve the addresses
>> for the variables.  So, from our perspective, it's a requirement.
>>
>>> For myself, I would much rather export ELF separately (e.g., a
>>> separate python API one can use independent of any particular
>>> tool, including gdb), and then have gdb provide the necessary
>>> glue to use this API. [I can imagine some compromises being
>>> needed, at least for now; e.g., it'd be cumbersome to read in all
>>> ELF symbols twice. But fixing that is just an optimization.]
>>
>> Ok, that's doable.  As it is, the section code mixes GDB and BFD
>> pretty heavily.  It shouldn't be too difficult to separate the two
>> out and push the section stuff into a new BFD python interface and
>> associate the objfiles with it.
>
> And here's what I've come up with.  Does this constitute enough of a
> separation?  It /should/ cross over into the BFD code in the same way
> that the GDB code does: As soon as we hit a bfd object or a
> bfd_section object, we call into bfd's new python API to generate the
> objects.
>
> https://jeffm.io/git/cgit.cgi/gnu/binutils-gdb/log/?h=gdb/python-bfd
>
> For the fully-integrated kdump work, use the python-bfd-kdump branch
> (or SUSE folks, python-bfd-kdump-buildid will pick up the separate
> debuginfos as we usually expect).

Separation isn't the issue, unfortunately.
The issue is that we cannot export bfd to python, period.

I'm certainly open to others convincing me I'm wrong.
But that is my understanding.
What we can do is export ELF, and that is what I'd like to see.