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

[Jeff Mahoney <jeffm at suse dot com>]

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On 2/3/16 1:30 PM, Doug Evans wrote:
> 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.

Ok, so looking at this again, I don't need full section information.
I just need a name.   Would it be acceptable to just export the name
of the section via gdb.Symbol and my new gdb.MinSymbol instead?

- -Jeff

- -- 
Jeff Mahoney
SUSE Labs
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