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

[Vincent Cheng]

On Sat, Sep 7, 2013 at 2:00 AM, Kurt Roeckx <kurt at roeckx.be> wrote:
> On Sat, Sep 07, 2013 at 01:53:26AM -0700, Vincent Cheng wrote:
>> 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.
>> "
>
> CAS being a compare and swap?  Which is the atomic function they want
> to use?

I don't know...

>> To me that sounds reasonable enough as to why we should be building
>> 0ad with -march=i686.
>
> Anyway, I have no idea if g++ supports those new atomic functions
> without -march=i686, but I at least hope so.

This is all beyond my knowledge, so the most I can do is just relay
messages back and forth between you and upstream if you have any
further questions...

>> >> > 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.
>
> I've triggerd that it gets build on barber, you should have a log
> about that in half an hour I guess.

Yep, built successfully [1] on barber, hence I think it's safe to say
that the bug is fixed (or that the original FTBFS issue isn't
reproducible anymore).

Vincent

[1] https://buildd.debian.org/status/fetch.php?pkg=0ad&arch=amd64&ver=0.0.14-2&stamp=1378546204