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Re: [PATCH,i386] cpuid function for prefetchw
On Mon, Aug 13, 2012 at 5:59 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Mon, Aug 13, 2012 at 2:10 PM, Jakub Jelinek <jakub@redhat.com> wrote:
>
>>> > To get the prefetchw cpuid flag, cpuid
>>> > function 0x80000001 needs to be called.
>>> > Previous to patch, function 0x7 is called.
>>> >
>>> > Bootstrapping and "make -k check" passes without failures.
>>> > Ok for trunk?
>>>
>>> IMHO you move it to a wrong spot, ecx bits of CPUID 0x80000001 are tested
>>> earlier.
>>>
>>> So I think you want this instead (bootstrap/regtest in progress):
>>>
>>> 2012-08-13 Ganesh Gopalasubramanian <Ganesh.Gopalasubramanian@amd.com>
>>> Jakub Jelinek <jakub@redhat.com>
>>>
>>> PR driver/54210
>>> * config/i386/driver-i386.c (host_detect_local_cpu): Test bit_PRFCHW
>>> bit of CPUID 0x80000001 %ecx instead of CPUID 7 %ecx.
>>> * config/i386/cpuid.h (bits_PRFCHW): Move definition to CPUID
>>> 0x80000001 %ecx flags.
>>
>> Now bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> OK, but I didn't find PRFCHW in the cpuid documentation to confirm the change.
>
> Thanks,
> Uros.
It is in Intel AVX spec:
http://software.intel.com/en-us/avx/
--
H.J.