Re: [PATCH 09/25] xor: move generic implementations out of asm-generic/xor.h

Eric Biggers
2026-02-28T07:15:30Z

On Thu, Feb 26, 2026 at 07:10:21AM -0800, Christoph Hellwig wrote:
> Move the generic implementations from asm-generic/xor.h to
> per-implementaion .c files in lib/raid.
>
> Note that this would cause the second xor_block_8regs instance created by
> arch/arm/lib/xor-neon.c to be generated instead of discarded as dead
> code, so add a NO_TEMPLATE symbol to disable it for this case.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

This makes the generic code always be included in xor.ko, even when the
architecture doesn't need it. For example, x86_64 doesn't need it,
since it always selects either the AVX or SSE code.

Have you considered putting the generic code in xor-core.c (or in
headers included by it) before xor_arch.h is included, and putting
__maybe_unused on the xor_block_template structs? Then they'll still be
available for arch_xor_init() to use, but any of them that aren't used
in a particular build will be optimized out as dead code by the
compiler.

lib/crc/ and lib/crypto/ take a similar approach for most algorithms.

- Eric