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Re: [PATCH] Define HAS_CPUID/HAS_I586/HAS_I686 from -march=


On 08/18/2015 11:52 AM, H.J. Lu wrote:
> On Tue, Aug 18, 2015 at 8:49 AM, Carlos O'Donell <carlos@redhat.com> wrote:
>> On 08/18/2015 09:34 AM, H.J. Lu wrote:
>>> On Mon, Aug 17, 2015 at 10:24 PM, OndÅej BÃlka <neleai@seznam.cz> wrote:
>>>> On Mon, Aug 17, 2015 at 04:10:05PM -0700, H.J. Lu wrote:
>>>>> cpuid, i586 and i686 instructions are available if the processor
>>>>> specified by -march= supports them.  We can use this information
>>>>> to determine whether those instructions can be used safely.
>>>>>
>>>>> OK for master?
>>>>>
>>>> Patch itself looks ok. It fixes theoretical problem that if there would
>>>> be new processor without cpuid it would cause problem.
>>>>
>>>> But could you explain rationale? Here you replaced one like with
>>>> equivalent longer macro and HAS_I586 is never used. Do you plan followup
>>>> patches that use that?
>>>
>>> I will use HAS_I586 and HAS_I686 in multi-arch for i486 and i586
>>> I am working on.
>>
>> Does this include folding i486 up a directory and doing away with the
>> i386 support? Since we need the i486 instructions to implement NPTL.
>>
>> https://sourceware.org/glibc/wiki/Development_Todo/Master#i386
>>
> 
> I will investigate it and it will take a while.
> 

Thanks :-)

Cheers,
Carlos.
 


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