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Date: Mon, 30 Mar 2026 23:47:42 -0700
From: Christoph Hellwig <hch@infradead.org>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: linux-crypto@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	Demian Shulhan <demyansh@gmail.com>,
	Eric Biggers <ebiggers@kernel.org>
Subject: Re: [PATCH 5/5] lib/crc: arm: Enable arm64's NEON intrinsics
 implementation of crc64
Message-ID: <actuDkpYbzLj0sI8@infradead.org>
References: <20260330144630.33026-7-ardb@kernel.org>
 <20260330144630.33026-12-ardb@kernel.org>
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Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org

>  	depends on CRC64 && CRC_OPTIMIZATIONS
> +	default y if ARM && KERNEL_MODE_NEON && !(CPU_BIG_ENDIAN && CC_IS_CLANG)

It would be useful to throw in a comment here why it is disabled for
big-endian on clang.

> +#define crc64_be_arch crc64_be_generic
> +
> +static inline u64 crc64_nvme_arch(u64 crc, const u8 *p, size_t len)
> +{
> +	if (len >= 128 && static_branch_likely(&have_pmull) &&
> +	    likely(may_use_simd())) {
> +		do {
> +			size_t chunk = min_t(size_t, len & ~15, SZ_4K);
> +
> +			scoped_ksimd()
> +				crc = crc64_nvme_arm64_c(crc, p, chunk);
> +
> +			p += chunk;
> +			len -= chunk;
> +		} while (len >= 128);
> +	}

>From reading the earlier patches, I'll assume arm SIMD code is
non-preemptable and thus you want the chunking here?  Maybe add
a little comment explaining that?