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

From: Christoph Hellwig <hch@lst.de>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
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Subject: Re: [PATCH 09/25] xor: move generic implementations out of asm-generic/xor.h
Date: Tue, 3 Mar 2026 17:09:11 +0100	[thread overview]
Message-ID: <20260303160911.GI7021@lst.de> (raw)
In-Reply-To: <20260228071521.GK65277@quark>

On Fri, Feb 27, 2026 at 11:15:21PM -0800, Eric Biggers wrote:
> 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.

True.  OTOH it is tiny.

> 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.

And earlier version did this, but it's a bit ugly.  What I might
consider is to require architectures that provide optimized version
to opt into any generic one they want to use.  This would require
extra kconfig symbols, but be a lot cleaner overall.