From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C5971125C0 for ; Fri, 7 Jun 2024 21:21:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717795286; cv=none; b=UJcMus6ygOPCwSek9UsA8+b0pi2ApAedVzQWGxSb4ts1m8JmMDJS3Wf2H1EgQEg+k/Rzt82MlZ0X7ebG6Fq53iJmAdKmu3GBPJ2k4qeDhjXwItOCOJY0AmNi6Z5szVj0PC21YqRymYdR1Du+jD1N00scrNFOJ0V3Z3lqHrOqUNc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717795286; c=relaxed/simple; bh=4jVn0C4rP9izfuziEvxAHgC5wbR9Zw6PLZ6CYGJjwdw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ijcnM1FgqNCw0FSpQKUEvuCZ+hmjY8CtBNCWT9icU/kt+OmmvQ35ueoW93cPVZkNHb4nsCpXyfumM9KyvZXdHa+lIiyPqspjZ3gO0PaFMgbiOvSgEVSByZwy1nURW4Ujh55lIkRXAEyWno9V/2pkBTfzxn9BhnhC+TfzZkqV850= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=IrCH+MBo; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="IrCH+MBo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8EA52C2BBFC; Fri, 7 Jun 2024 21:21:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717795286; bh=4jVn0C4rP9izfuziEvxAHgC5wbR9Zw6PLZ6CYGJjwdw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=IrCH+MBoJS1yRbTDYvFTdCKXFdTUcuwZz2Vu/J2EMfRx7GatNZwNGhtrcxRaoUOqB 2rOopd1WJ5V3DW6C2/1pHzQuIyMWV33jcgWvJANTIJ9smixfH6KtFJHEMtHix/fnj8 /jLnRUK+bTq13jYncBAj7VKfqJFEPpTH4YgTstFS5KMbsbaPP6bxaeA43xbrq3DBf/ D2MET/98UnTx+g3tnVazFolQgsNtv3lyBX4f5/ZaRaTfy+8YZzdqgYY9X98FpxmINH YMKkONwJ6pin9hS5bt5ltx3j0qT7JX+macyrot/+ZvJ20DytxDt6I042NaeTftxgqE TT+Q3CKLzwz8Q== Date: Fri, 7 Jun 2024 22:21:19 +0100 From: Conor Dooley To: Charlie Jenkins Cc: Jesse Taube , linux-riscv@lists.infradead.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Evan Green , Andrew Jones , Xiao Wang , =?iso-8859-1?Q?Cl=E9ment_L=E9ger?= , Andy Chiu , Greentime Hu , Heiko Stuebner , Guo Ren , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Costa Shulyupin , Andrew Morton , Baoquan He , Sami Tolvanen , Zong Li , Ben Dooks , Erick Archer , Vincent Chen , Joel Granados , linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] RISC-V: Detect unaligned vector accesses supported. Message-ID: <20240607-wildfowl-baggage-54f622e18c4a@spud> References: <20240606183215.416829-1-jesse@rivosinc.com> <20240606183215.416829-2-jesse@rivosinc.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-sha256; protocol="application/pgp-signature"; boundary="8YS9Sx3fQh2vamL3" Content-Disposition: inline In-Reply-To: --8YS9Sx3fQh2vamL3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Jun 07, 2024 at 02:06:27PM -0700, Charlie Jenkins wrote: > On Fri, Jun 07, 2024 at 03:53:23PM -0400, Jesse Taube wrote: > > On 6/6/24 19:13, Charlie Jenkins wrote: > > > On Thu, Jun 06, 2024 at 02:29:23PM -0700, Charlie Jenkins wrote: > > > > On Thu, Jun 06, 2024 at 02:32:14PM -0400, Jesse Taube wrote: > > > > Please use the exising UNKNOWN terminology instead of renaming to > > > > SUPPORTED. Any option that is not UNSUPPORTED implies that unaligned > > > > accesses are supported. > >=20 > > Conor didnt like using UNKNOWN a proxy for "SUPPORTED" I did say this, but in the context of wanting you to actually add the performance probing (and potentially the other infrastructure that Charlie added for scalar). > > Having SUPPORTED is better then assuing the speed to be slow. >=20 > The HWPROBE key is about misaligned access performance. UNKNOWN means > that the performance is unknown. Right. I also don't think that assuming "slow" is even problematic - seemingly all extant hardware doesn't even support misaligned access. But really, just whack in the probing, it shouldn't be too bad, right? > The scalar and vector names need to > match up. That's definitely not the case. A different hwprobe key is allowed to behave differently, but... > UNKNOWN was already merged and is supported by linux so if you > want to use SUPPORTED here then you need to add a scalar SUPPORTED key > that is an alias of the UNKNOWN key. =2E..this suggestion of a scalar change I disagree with anyway, so it's moot. Unknown should be a state that we only have internally when we actually do not know, and not something that userspace should ever see, unless there's a bug in the probing code IMO. Unknown gives userspace no actionable information anyways. > I would rather keep UNKNOWN as it > is, but that's up to you. --8YS9Sx3fQh2vamL3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEABYIAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCZmN5zwAKCRB4tDGHoIJi 0jBSAQDIvHDI37c072Vzga9uhMAIgoc0xvFIzXF+e0LwVNEQ/AEAysNxEGOD0UHM UlCyN4BTtw9qVQIFJcyKgqX6txxrVAs= =4Qyu -----END PGP SIGNATURE----- --8YS9Sx3fQh2vamL3--