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

[H.J. Lu]

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, Ondřej Bílka <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.


-- 
H.J.