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Re: [PATCH 1/3] Enable Intel WAITPKG instructions.
>>> On 15.04.18 at 15:33, <hjl.tools@gmail.com> wrote:
> On Sun, Apr 15, 2018 at 6:27 AM, Jan Beulich <jbeulich@suse.com> wrote:
>>>>> "H.J. Lu" <hjl.tools@gmail.com> 04/15/18 3:01 PM >>>
>>>On Sun, Apr 15, 2018 at 5:16 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>>> They should be treated similar to pinsrw. That is both r32/r64 are allowed and
>>>> REX.W is skipped. As for suffix, we shouldn't add them since these are new
>>>> instructions.
>>>
>>>Here is the path.
>>
>> I can live with there not being suffixes, but I don't think "tpause rcx"
> should
>> be encoded without REX.W (and hence decode as "tpause ecx").
>>
>
> They are no difference from other instructions where only the lower 32 bits
> are used.
Agreed, yet if the programmer says "rcx" then (s)he should get rcx (i.e.
REX.W set unless an insn defaults to 64-bit operand size), not ecx. I do
think this is wrong for a few other insns as well.
Jan