From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 373B42C11FE for ; Wed, 3 Jun 2026 13:18:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780492683; cv=none; b=Uw2bsOqL34yjql0SiEboJnfpolIcjoTtVH36WFus58SgBJCX4Nx0IPug37wts3v7iSaiRW2IL6ksCVaZJRKCQ4/bLFqxQIAeq/6jGMPu8x1oZh+IklWu2upP8Vh52eBwItWtmkHFwYIZP8eEP2kAVCjOGyTXGFJfVCFuJhIgST4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780492683; c=relaxed/simple; bh=GRDuRbDrtLCr2WrVymV/ZF9TJbGJHMnXoOmGEu85lXU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WBVFeIar57wU83as+Lf7N6OhmvBeXr3gzO2LqpWw+l6fvEDBs1lY6AcJg2/HmWb651sJ4xw/lXVAWB+gOcqfHshstYXL4jt4qsToghwNf7Afn/C0P3QzbcfKks8zp/DtzQCLeIG4iSdUUJxajBeF2ZNAfQKxEZTp+fqtoL8nSho= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fWiy5YEM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fWiy5YEM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 158C31F0089D; Wed, 3 Jun 2026 13:17:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780492681; bh=GRDuRbDrtLCr2WrVymV/ZF9TJbGJHMnXoOmGEu85lXU=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=fWiy5YEMpb0lndWGWO0ApBHOCMOzSwAdvFPMd9IdbKMcXH0ELtPdEmnU3PExesIQz Or8//A5jWaBihFyzHy2LIUDj8cF/QmAPbo5aYQWWX7RSF+zWVag5VOx4VV6Wz7e3RN c8hR7v7S4JFBH0NwW4KB/5zVKITr+Bs6LtrgqfpWDUuFy8RBCa8hqRV5YDkSeQ7Fv+ zP4O8XFJZ+sz5HHv8yy48kCLFKVV9Ts5BjcAXShD/Ny9WxdoHlX1sHpHVYm0F5tOHw 9MzFzOW68UFeC1MXw3tLCSlctiV3FTtum2/I6fZ3wKli7u2ay5CpcL+sHZri3MM3Ev DPS3wgLJVYLUQ== Date: Wed, 3 Jun 2026 14:17:57 +0100 From: Conor Dooley To: Qingwei Hu Cc: Vivian Wang , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Deepak Gupta , Pincheng Wang , Chunyan Zhang , Hui Wang , =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= , Xu Lu , Guodong Xu Subject: Re: [PATCH v1] riscv: cpufeature: Add Zic64b ISA extension support Message-ID: <20260603-scanner-justly-51cd1160460c@spud> References: <20260528141630.2741710-1-qingwei.hu@bytedance.com> <302dfaf7-4a38-408f-997e-68ed27de2341@iscas.ac.cn> <752F28EA-9255-4DBE-8007-F57947305D71@bytedance.com> <20260530-spoils-studied-d0858257c982@spud> <68DF4B69-6693-447A-ADAC-E943F96CFB77@bytedance.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="UaAKlaNtj6N9O0G6" Content-Disposition: inline In-Reply-To: <68DF4B69-6693-447A-ADAC-E943F96CFB77@bytedance.com> --UaAKlaNtj6N9O0G6 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 03, 2026 at 08:32:14PM +0800, Qingwei Hu wrote: >=20 >=20 > > On May 31, 2026, at 07:09, Conor Dooley wrote: > >=20 > > On Sat, May 30, 2026 at 11:36:11AM +0800, Qingwei Hu wrote: > >> Hi Vivian, > >>=20 > >> Thanks for the feedback. > >>=20 > >>> On May 29, 2026, at 11:14, Vivian Wang wrot= e: > >>>=20 > >>> On 5/28/26 22:16, Qingwei Hu wrote: > >>>> Zic64b describes a platform with 64-byte cache block sizes. It is a > >>>> mandatory part of RVA23U64, but a system may provide 64-byte CMO blo= ck > >>>> sizes without satisfying all profile requirements. > >>>>=20 > >>>> The ISA string parser currently ignores Zic64b because the extension= is > >>>> not present in the cpufeature table. Add an ISA extension ID and tab= le > >>>> entry for Zic64b so it can be reported in /proc/cpuinfo when firmware > >>>> advertises it. > >>>=20 > >>> I'd like to understand: What is the motivation to doing this, given t= hat > >>> the very same information is already available as riscv,cbo*-block-si= ze > >>> and hwprobe? > >>=20 > >> The motivation here is not to replace riscv,cbo*-block-size or hwprobe. > >> Those are still the right interfaces for software that needs the actual > >> CBO block size. > >>=20 > >> This is more about preserving the ISA extension name reported by > >> firmware. Some platforms report zic64b in the ISA string, but Linux > >> currently drops it because there is no cpufeature entry, so cpuinfo no > >> longer matches what firmware advertised. That makes profile/ISA-string > >> comparison tools a bit awkward. > >>=20 > >> So the patch only makes zic64b visible as a named ISA extension when > >> firmware reports it, while still validating it against any CBO block > >> sizes that firmware provides. > >>=20 > >>> If an extension is what we want to go with, then > >>> Documentation/devicetree/bindings/riscv/extensions.yaml also needs > >>> updating to match. > >>=20 > >> And yes, if we keep this direction, I agree extensions.yaml should be > >> updated in v2. > >=20 > > And make sure that having zic64b makes the cbo*-block-size properties > > mandatory so that people don't confuse themselves and omit them and > > wonder why stuff doesn't work. > >=20 > > Does zic64b mean that all of the zicbo* extensions are supported, or > > does it just mean that the supported ones use 64-byte block sizes? > > The answer to that will impact how you make the cbo*-block-size > > properties mandatory. > >=20 > > Cheers, > > Conor. >=20 > Thanks, I will check this with the RISC-V unprivileged/ISA folks first, > and then handle the binding accordingly in v2. I noticed that there's another series that's adding zic64b support: https://lore.kernel.org/all/20260603-rva23u64-hwprobe-v2-v3-0-5529a7b28384@= gmail.com/ Probably you should coordinate with Guodong, as your zic64b effort seems to predate theirs. --UaAKlaNtj6N9O0G6 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCaiApgQAKCRB4tDGHoIJi 0uMwAP4zjcEJQpZ9LD1FnsoVGechkZwKoq1Siq9FIJYJAU8H/gEA4MAHmgERrx/D ea3OryDGTN56AfqUo63gAyFosUY17wY= =VaZR -----END PGP SIGNATURE----- --UaAKlaNtj6N9O0G6--