linux-kernel - Re: [PATCH v2 0/4] riscv: hwprobe: Add Zicbop support

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Message-ID: <20251009-440720dc2e40b8a0b8296956@orel>
Date: Thu, 9 Oct 2025 12:09:57 -0500
From: Andrew Jones <ajones@...tanamicro.com>
To: Yao Zihong <zihong.plct@...c.iscas.ac.cn>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	alexghiti@...osinc.com, shuah@...nel.org, samuel.holland@...ive.com, evan@...osinc.com, 
	cleger@...osinc.com, zihongyao@...look.com, zhangyin2018@...as.ac.cn, 
	Paul Walmsley <pjw@...nel.org>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>
Subject: Re: [PATCH v2 0/4] riscv: hwprobe: Add Zicbop support

On Thu, Oct 09, 2025 at 09:41:50PM +0800, Yao Zihong wrote:
> Changes since v1:
> ------------------
> - Bump RISCV_HWPROBE_MAX_KEY (modified 1/4).
> - Add documentation for the Zicbop hwprobe bit/key (new 3/4).
> - Add a selftest(prefetch.c) for Zicbop (new 4/4).
> 
> Add UAPI and kernel plumbing to expose the Zicbop extension presence
> and its block size through hwprobe. The interface mirrors
> Zicbom/Zicboz. This allows userspace to safely discover and optimize
> for Zicbop when available.
> 
> Background: Zicbop is mandated by the RVA22U64 profile. Downstream may
> combine the presence bit with ZICBOP_BLOCK_SIZE to make profile-level
> policy decisions or enable Zicbop-specific optimizations.
> 
> Yao Zihong (4):
>   uapi: riscv: hwprobe: Add Zicbop extension bit and block-size key
>   riscv: hwprobe: Report Zicbop presence and block size
>   docs: riscv: Document hwprobe for Zicbop
>   selftests/riscv: Add Zicbop prefetch test
> 
>  Documentation/arch/riscv/hwprobe.rst          |   8 +-
>  arch/riscv/include/asm/hwprobe.h              |   2 +-
>  arch/riscv/include/uapi/asm/hwprobe.h         |   2 +
>  arch/riscv/kernel/sys_hwprobe.c               |   6 +
>  .../testing/selftests/riscv/hwprobe/Makefile  |   5 +-
>  .../selftests/riscv/hwprobe/prefetch.c        | 236 ++++++++++++++++++
>  6 files changed, 256 insertions(+), 3 deletions(-)
>  create mode 100644 tools/testing/selftests/riscv/hwprobe/prefetch.c
> 
> -- 
> 2.47.2
>

I'm not sure why patches 1-3 aren't just squashed together like commit
eb1003970940 ("RISC-V: hwprobe: Expose Zicbom extension and its block
size") does for zicbom.

Thanks,
drew