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Re: [PATCH] x86: Replace CpuABM with CpuPOPCNT
On Mon, Feb 17, 2020 at 7:40 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 17.02.2020 16:27, H.J. Lu wrote:
> > AMD ABM has 2 instructions: popcnt and lzcnt. ABM CPUID feature bit has
> > been reused for lzcnt and a POPCNT CPUID feature bit is added for popcnt.
> > This patch removes CpuABM and adds CpuPOPCNT. It changes ABM to enable
> > both lzcnt and popcnt, changes SSE4.2 to also enable popcnt.
>
> I don't think removing support for something may have in active and
> working use is a good idea. Adding some better mechanism as
> _suggested_ replacement is of course fine, but people would better
> not be forced to change their _correct_ code because of gas side
> change.
No assembly code changes are needed. The .abm directive still works
as before. My patch only changes assembler internal implementation.
--
H.J.