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From: Usama Arif <usama.arif@linux.dev>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Usama Arif <usama.arif@linux.dev>,
	david.laight.linux@gmail.com, bp@alien8.de,
	dave.hansen@linux.intel.com, dsterba@suse.com, hpa@zytor.com,
	linux-kernel@vger.kernel.org, mingo@redhat.com, terrelln@fb.com,
	tglx@kernel.org, x86@kernel.org, kas@kernel.org,
	hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev,
	kernel-team@meta.com
Subject: Re: [PATCH v2] x86/lib: Use REP MOVSB for large memcpy() on ERMS CPUs without FSRM
Date: Wed, 11 Nov 2026 05:04:03 -0800	[thread overview]
Message-ID: <20261111130404.2662582-1-usama.arif@linux.dev> (raw)
In-Reply-To: <CAHk-=whPF8CD9zC960jPUi2rMrJ_pq9ytdSYqWoef-R6AHsfXg@mail.gmail.com>

On Tue, 10 Nov 2026 09:53:07 -0800 Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Wed, 4 Nov 2026 at 14:28, Usama Arif <usama.arif@linux.dev> wrote:
> >
> > +       ALTERNATIVE __stringify(cmpq $0x20, %rcx; jb .Lhandle_tail), \
> > +                   __stringify(rep movsb; RET), X86_FEATURE_FSRM
> 
> Let's not do that.
> 
> Putting magic things like RET in alternatives is just a bad bad idea.

I will send v3 today with RET in ordinary text.

Thanks!
Usama

> 
>                Linus
> 

      parent reply	other threads:[~2026-11-11 13:04 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-04 22:28 Usama Arif
2026-11-05  8:12 ` David Laight
2026-11-05 17:28   ` Usama Arif
2026-11-10 16:25 ` Kiryl Shutsemau
2026-11-10 17:06   ` David Laight
2026-11-11 13:02     ` Usama Arif
2026-11-11 12:58   ` Usama Arif
2026-11-10 17:53 ` Linus Torvalds
2026-11-10 19:33   ` David Laight
2026-11-10 20:17   ` H. Peter Anvin
2026-11-10 20:59     ` Linus Torvalds
2026-11-10 22:35       ` David Laight
2026-11-11  1:16       ` Borislav Petkov
2026-11-11 13:24         ` Usama Arif
2026-11-10 21:00     ` David Laight
2026-11-11  0:24       ` H. Peter Anvin
2026-11-11 13:04   ` Usama Arif [this message]

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