Bug#712956: marked as done (0ad: seems to use CPU features not available everywhere)

[Vincent Cheng]

On Sat, Sep 7, 2013 at 1:46 AM, Kurt Roeckx <kurt at roeckx.be> wrote:
> On Sat, Sep 07, 2013 at 01:21:59AM -0700, Vincent Cheng wrote:
>> On Sat, Sep 7, 2013 at 1:02 AM, Kurt Roeckx <kurt at roeckx.be> wrote:
>> > reopen 712956
>> > thanks
>> >
>> >>  nvidia-texture-tools (2.0.8-1+dfsg-4) unstable; urgency=low
>> >>  .
>> >>    [ Fabio Pedretti ]
>> >>    * Add armel and armhf build support (Closes: #721972)
>> >>    * Remove -march=athlon64 from CXXFLAGS (Closes: #713966, #712956)
>> >
>> > This is clealy the wrong bug you're closing.  It's assigned to
>> > 0ad.
>> >
>> > 0.0.14-2 is still using -msse -march=i686 on i386
>>
>> See explanation by upstream here [1]. If compiling with -march=i686 is
>> strictly not allowed on Debian i386, I can just simply stop building
>> 0ad for i386, although I'm not sure if that's necessary at all; the
>> package has been sitting in the archive for over a year and I still
>> haven't gotten any complaints about 0ad not running on any Debian
>> user's i386 machine.
>
> I don't know if having i686 is acceptable or not.  But I currently
> see no good reason for it.  [1] is my own comment.  The only reply
> to that is that they still use the legacy functions, and no reply
> as to why they need to keep using it and can't move to the new
> ones.

Err, sorry, should have linked to comment #7 instead in that ticket. [1]

"
We wouldn't run on an actual 486 due to use of several newer CPU
instructions, one of which is the CAS in ia32.cpp. If indeed we have
to compile with -march=i486, which sounds like a last resort, the CAS
could be replaced with GCC-specific assembly, and we'd have a decent
hope of compiling successfully.
"

To me that sounds reasonable enough as to why we should be building
0ad with -march=i686.

>> > It wasn't using -march=athlon64 on amd64 before either as far as I
>> > know but had problem running on at least one of the buildds.
>>
>> The original issue was that nvidia-texture-tools was compiled with
>> -march=athlon64, which caused one of the amd64 buildds to complain
>> about an "Illegal instruction" when trying to run 0ad's test suite
>> when building 0ad. There's a relevant issue filed against upstream
>> nvidia-texture-tools about this as well. [2]
>
> So that was #713966 and that was fixed in 0ad with the 0.0.14-2
> uploaded?

Yes, should be fixed now, but again, since I don't have any hardware
where I can reproduce this locally, I suppose the only way to prove
that this is fixed is to have 0ad 0.0.14-2 be rebuilt on barber.

Regards,
Vincent

[1] http://trac.wildfiregames.com/ticket/1994#comment:7