Re: [PATCH 18/25] x86: move the XOR code to lib/raid/

Peter Zijlstra
2026-02-28T10:32:03Z

On Fri, Feb 27, 2026 at 03:55:29PM -0800, Eric Biggers wrote:
> On Fri, Feb 27, 2026 at 03:30:16PM +0100, Peter Zijlstra wrote:
> > On Thu, Feb 26, 2026 at 07:10:30AM -0800, Christoph Hellwig wrote:
> > > Move the optimized XOR code out of line into lib/raid.
> > >
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > ---
> > > arch/x86/include/asm/xor.h | 518 ++----------------
> > > arch/x86/include/asm/xor_64.h | 32 --
> > > lib/raid/xor/Makefile | 8 +
> > > .../xor_avx.h => lib/raid/xor/x86/xor-avx.c | 14 +-
> > > .../xor_32.h => lib/raid/xor/x86/xor-mmx.c | 60 +-
> > > lib/raid/xor/x86/xor-sse.c | 476 ++++++++++++++++
> >
> > I gotta ask, why lib/raid/xor/$arch/ instead of something like
> > arch/$arch/lib/xor ?
>
> Similar to lib/crypto/ and lib/crc/, it allows the translation units
> (either .c or .S files) containing architecture-optimized XOR code to be
> included directly in the xor.ko module, where they should be.
>
> Previously, these were always built into the core kernel even if
> XOR_BLOCKS was 'n' or 'm', or they were built into a separate module
> xor-neon.ko which xor.ko depended on. So either the code was included
> unnecessarily, or there was an extra module.
>
> Technically we could instead have the lib makefile compile stuff in
> arch/, but that would be unusual. It's much cleaner to have the
> directory structure match the build system.

Hmm, I suppose. Its just weird that we now have to look in both
arch/$foo and lib/*/$foo/ to find all arch code.

And I don't suppose symlinks would make it better?