Re: [RFC] [Question] memset.S old code stuff

[Mark Rutland <mark.rutland@arm.com>]

On Tue, Aug 04, 2026 at 04:57:54PM +0100, Catalin Marinas wrote:
> On Thu, Jul 23, 2026 at 12:17:15AM +0100, Bradley Morgan wrote:
> > Hey folks, sorry for the crazy asm emails, I see that in memset.S in
> > arch/arm64/lib/memset.S, the code is incredibly old code, like 2013 old
> > (heh).
> > 
> > I was wondering if I could say, adapt it from optimized-routines (same
> > treatment as memcpy.S essentially.
> 
> I think Robin attempted until he realised the use of the Q registers in
> the Cortex Strings library, mentioned here:
> 
> https://lore.kernel.org/all/cover.1571073960.git.robin.murphy@arm.com/

We also subsequently looked at moving away from Cortex-strings entirely,
e.g.

  https://lore.kernel.org/linux-arm-kernel/20230314115030.347976-1-mark.rutland@arm.com/

... but there were open questions on the semantics, and no clear path
forwards at the time.

Writing the code isn't the hard part. We need to get wider agreement on
the semantics, test on a variety of platforms, etc.

For now, I think it'd be best to leave as-is, since it's a time sink for
reviewers.

Mark.