[PATCH V2 0/2] Split tdesc_(amd64|i386)_mpx into tdesc(amd64|i386)_mpx_* and tdesc(amd64|i386)_avx_mpx_*
Pedro Alves
palves@redhat.com
Thu Apr 14 11:33:00 GMT 2016
On 04/14/2016 11:29 AM, Yao Qi wrote:
> Walfred Tedeschi <walfred.tedeschi@intel.com> writes:
>
>> CPU features can occur in any combination. The current assumption that
>> feature "A" implies in feature "B" does not necessarily hold.
>>
>> This patch series construct an additional combination of the Intel(R)
>> Memory Protection Extensions (MPX) with Intel(R) Advanced Vector
>> Extensions (AVX).
>
> First of all, I am not against your patches. Just think a little more
> after reading them...
>
> This reveals a problem in gdb target description. It doesn't scale very
> well if processors have multiple different features, and features can be
> combined differently. A processor family has three features A, B, and
> C, and each processor implementation may have one, two or three of these
> features. In gdb target description, we need to have many *.xml and *.c
> files, for these combinations like, A, B, C, AB, AC, BC, and ABC.
>
> The root cause is that target description are static and pre-generated.
> If the target description can be generated dynamically according to the
> cpuid or AT_HWCAP, that would be simpler. In this way, we only have to
> define target descriptions for feature A, B, and C, and GDB/GDBserver
> combine them together in the runtime.
I agree. This is not the first time this is suggested. If someone were
to do it, I'd be in favor too.
Thanks,
Pedro Alves
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