Re: [RFC 00/13] MIPS64 support

[Crestez Dan Leonard <cdleonard at gmail dot com>]

On Tue, Sep 2, 2014 at 9:05 PM, Josh Stone <jistone@redhat.com> wrote:
> On 09/01/2014 06:47 AM, Crestez Dan Leonard wrote:
>> I pushed an updated version of the mips patches to github:
>> https://github.com/cdleonard/systemtap/commits/mips . The patches are
>> ordered roughly by hackiness. The first 7 (up to and including
>> b0c93e569acca2db978c7c557ad929fa041b8669) should be mostly
>> uncontroversial and add basic mips support. Maybe we could get those
>> in and then discuss the rest? I would very much like to merge this, I
>> have no desire to maintain these patches separately.
>
> Ok, I'll review from there when I can, hopefully next week sometime.  I
> definitely understand not wanting to carry patches separately.  But even
> when it's merged, please understand that most of us Red Hat folks don't
> work with mips machines, so we'll still have to rely on interested
> parties like yourself to make sure it doesn't regress.

Sounds great. Let me know if you would rather have me post those 7
patches as individual emails to the list. It's a little spammy but
very useful for reviewing.

>> The new release of elfutils 0.160 adds an API which can be used to
>> avoid patch 7 "loc2c: Add Dwarf pointer to location_context". I'll
>> rewrite that part, if it helps to get the patch into upstream. Other
>> than that it's not clear that it's elfutils job to fix the other
>> issues. I chose to restrict my patches to one project.
>
> I think the 0.160 API is a better way to go, especially since the main
> Dwarf may not even be the right container for a given DIE when things
> like .gnu_debugaltlink are considered.  That shouldn't be an issue for
> is_elf_mips64(), but might matter if we ever want loc2c to make other
> queries on the Dwarf structure.
>
> But do guard that with _ELFUTILS_PREREQ please, so we don't force the
> new minimum elfutils on everyone.  Whatever mips-stap documentation you
> write can explain under what circumstances this is really necessary.

I will adjust my patch using the new elfutils API and avoid bumping
elfutils globally. It's not strictly required for minimal mips
support.

--
Regards,
Leonard