From: Jakub Jelinek <jakub@redhat.com>
To: Andrew Haley <aph@redhat.com>
Cc: pinskia@gmail.com,
"libffi-discuss@sourceware.org"
<libffi-discuss@sourceware.org>
Subject: Re: Xeon Phi
Date: Tue, 14 Oct 2014 10:08:00 -0000 [thread overview]
Message-ID: <20141014100808.GY10376@tucnak.redhat.com> (raw)
In-Reply-To: <543CEA22.9020302@redhat.com>
On Tue, Oct 14, 2014 at 10:17:22AM +0100, Andrew Haley wrote:
> On 14/10/14 10:16, pinskia@gmail.com wrote:
>
> >
> >> On Oct 14, 2014, at 2:14 AM, Andrew Haley <aph@redhat.com> wrote:
> >>
> >> What's the status of Xeon Phi support? There seem to be some packages on the
> >> Interweb, but I don't see anything in libffi git.
> >
> > Xeon phi is just x86_64 linux.
>
> No it's not. There is a completely different FPU and a different ABI.
I guess it really depends on which Xeon Phi you are talking about.
There is Knights Ferry, which has been a prototype only, then
Knights Corner, which is the one currently shipping, which AFAIK is
a stripped down i586-ish (but 64-bit) ISA (so, no MMX/SSE and later,
no CMOV and various other post-i586 ISA additions) with i387 FPU
and a 512-bit vector unit. This isn't really supported by vanilla GCC,
patches exist AFAIK for the non-vector unit part, but the vector unit isn't
really supported in GCC. Not sure what exact ABI is this one using,
supposedly some x86-64-ish ABI, just with what is passed normally in SSE/SSE2
registers is passed in the zmm? registers of the vector unit?
Then there is going to be Knights Landing, see
http://en.wikipedia.org/wiki/Xeon_Phi
which is likely going to be pretty standard x86-64-ish ABI and ISA
(contemporary Airmont), with AVX512F etc. extensions, fully supported by GCC.
So, for the last one, I don't think any extra support is really needed
(unless libffi has supports for AVX/AVX2 vectors already, then AVX512
support would be needed too).
Jakub
next prev parent reply other threads:[~2014-10-14 10:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-14 9:14 Andrew Haley
2014-10-14 9:16 ` pinskia
2014-10-14 9:17 ` Andrew Haley
2014-10-14 9:52 ` Anthony Green
2014-10-14 10:08 ` Jakub Jelinek [this message]
2014-10-14 10:23 ` Andrew Haley
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