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

On Tue, Aug 18, 2015 at 8:49 AM, Carlos O'Donell <> wrote:
> On 08/18/2015 09:34 AM, H.J. Lu wrote:
>> On Mon, Aug 17, 2015 at 10:24 PM, OndÅej BÃlka <> 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.

I will investigate it and it will take a while.


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