From: Eric Biggers <ebiggers@kernel.org>
To: Rakuram Eswaran <rakuram.e96@gmail.com>
Cc: ardb@kernel.org, corbet@lwn.net, linux-crypto@vger.kernel.org,
linux-doc@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org,
skhan@linuxfoundation.org
Subject: Re: [PATCH] Documentation/staging: Fix typo and incorrect citation in crc32.rst
Date: Sat, 23 Aug 2025 22:36:23 -0400 [thread overview]
Message-ID: <20250824023623.GB12644@quark> (raw)
In-Reply-To: <20250823091837.5037-1-rakuram.e96@gmail.com>
Hi Rakuram,
On Sat, Aug 23, 2025 at 02:48:32PM +0530, Rakuram Eswaran wrote:
> Thanks for applying my patch!
>
> I noticed your comment about the file being dated.
> I’d be interested in helping to update it to cover the more modern
> CRC implementations — things like carryless multiplication and
> hardware CRC instructions on x86, ARM, etc.
>
> Since I’m not very familiar yet with these optimized approaches.
> Could you suggest a good starting point for exploring this in the kernel
> (or any references you recommend)?
>
> I was planning to look at lib/crc32.c and the arch-specific
> implementations, but would appreciate your guidance.
>
> Best Regards,
> Rakuram
https://www.corsix.org/content/alternative-exposition-crc32_4k_pclmulqdq
has a fairly good explanation.
In the kernel, x86 uses crc32 instructions for crc32c(), and arm64 uses
crc32 instructions for crc32c(), crc32_le(), and crc32_be().
x86, arm, arm64, powerpc, s390, and riscv all have CRC implementations
using carryless multiplication instructions. The riscv one might be the
easiest to read since it is mostly written in C, rather than assembly.
See: lib/crc/riscv/crc-clmul-template.h
- Eric
prev parent reply other threads:[~2025-08-24 2:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-20 16:26 [PATCH] Documentation/staging: Fix typo and incorrect citation in crc32.rst Rakuram Eswaran
2025-08-21 3:59 ` Eric Biggers
2025-08-23 9:18 ` Rakuram Eswaran
2025-08-24 2:36 ` Eric Biggers [this message]
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