Re: [PATCH 0/8] gdb/s390: Add regular and fast tracepoint support.

Pedro Alves
2016-01-25T15:57:04Z

On 01/25/2016 02:28 PM, Marcin KoÅ›cielnicki wrote:
> On 25/01/16 14:56, Pedro Alves wrote:
>> On 01/24/2016 12:12 PM, Marcin KoÅ›cielnicki wrote:
>>
>>> 1. Target independent: tfile format doesn't contain target information
>>> (tdesc). While this affects all platforms with multiple tdescs
>>> (eg. x86_64 is unable to pull AVX registers from tfile for that
>>> reason), it horribly breaks 31-bit s390 with high GPRs - it has
>>> a completely different GPR layout from plain 31-bit s390, so the
>>> collected registers will be garbled. I suppose the proper fix to
>>> that would be to add tdesc information to tfile format.
>>
>> Yes, I think so too.
>>
>>> Unfortunately, I don't see a way to extend it in a backwards-compatible way.
>>
>> The trace file header is just a list of newline-terminated lines.
>> We're free to add more header lines - older gdb's just warn about
>> unknown lines. See tfile_interp_line.
>>
>> Thanks,
>> Pedro Alves
>>
>
> Very well.
>
> I was thinking of just stuffing the XML in the header. We can avoid
> embedded newlines through hex-encoding it (or just stripping them,
> shouldn't hurt XML...), and copy it straight from the target. That
> would fail for targets that don't get tdesc from XML, but I'm not sure
> we should worry about it. An alternative would be to invent some
> serialization format for tdesc in tfile, but why do that when we already
> have a perfectly good one...
>
> Should be quite simple, really. Does that sound OK?

Yes.

Thanks,
Pedro Alves