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 1FADD7F7EF; Tue, 23 Jan 2024 18:11:57 +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=1706033518; cv=none; b=m+1SLd5KVnN9rHGvFZ1PcfkJBtHYVZwMFY9313xE+LCTjuJ9qTRETMa8pKeyfyGjLa1AvDyAyan/SSC2QFjtf7kA0ExmiJAkuwpa9DdHOYSO7jny8m1OR+HGXJMEw4IF88urra773XaKgEHwqR2lAfu38knhTlGcyL9ToBLPqz8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706033518; c=relaxed/simple; bh=Qf9mEHht3yUIqrNjZxcQ0bvTqZFpCh/XYVvpOp1vhmI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=FIhDHhI8h9AcHdAgEl2rHPO0jTB2jQozs6H3YF8heI6QytNUKK3iFiiCGi8wZzJclVxQEGO8Twdd7HOsUtyJXUGZAKSmA815Jk69QbBPf4maFJiOns0sXpnSs/CE7/Rj2I18JU4xvdAOca77tFnKwkvoUnqAed/HMccge0+erzc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ppuFVYeb; 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="ppuFVYeb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C27E7C433C7; Tue, 23 Jan 2024 18:11:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1706033517; bh=Qf9mEHht3yUIqrNjZxcQ0bvTqZFpCh/XYVvpOp1vhmI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ppuFVYebG5/NFWOdMx0aN3LAZR5fz7XrXEFb9o2k0quNnBo4yC2Z5fY4Gm1Vt7jYJ 4t2l0Td6vG/kjN3Rr5JFnBE7N6FpUgZ0wE+DnWihwKhFbGNGfzHHoeN7/DNh0IJ8VF xIcmmzyjga/W76qQnB94MosrRVU7ZQc0lvNL9r2EAWaA7yyf8Fi2qSMv1MkSyZKXrY TeVi6nzpG9zBF31kiv2tfDACH4MZYUO3vyPacMvoX+7G1iXEN/+R8Np7N/sfwayHD2 Un09gAz7CnKaIjLJSGlYCwFz5X89gYXIp+VdaMd972HYDMzhjsaq72R/ml37YmutEv GjaBZNK+LWDQA== Date: Tue, 23 Jan 2024 18:11:52 +0000 From: Mark Brown To: Dave Martin Cc: Catalin Marinas , Will Deacon , Jonathan Corbet , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Edmund Grimley-Evans Subject: Re: [PATCH 1/4] arm64/sve: Remove bitrotted comment about syscall behaviour Message-ID: References: <20240122-arm64-sve-sme-doc-v1-0-3d492e45265b@kernel.org> <20240122-arm64-sve-sme-doc-v1-1-3d492e45265b@kernel.org> <991d84b4-e184-4fd6-900f-601f8c31d518@sirena.org.uk> 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="gmVr7hQh/YIa4C2A" Content-Disposition: inline In-Reply-To: X-Cookie: Stay together, drag each other down. --gmVr7hQh/YIa4C2A Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Jan 23, 2024 at 05:54:17PM +0000, Dave Martin wrote: > I still feel that it is iffy practice for userspace to rely on the > extra bits being zeroed -- I think the architecture hides this > guarantee anyway whenever you go through a function call confirming to > the regular procedure call standard (including the syscall wrappers). > But there may not be a lot of point trying to put people off if we > can't force them not to rely on it. I do tend to agree that the requirement to zero is excessively zealous and that the risk from relaxing it is minor (it's stricter than the function call ABI), I did leave a sysctl as a mechanism for restoring compatibility in the case where we did run into issues in my original series but I didn't expect to need it. If you convince everyone else I'd be happy to relax things but I don't super care either way. --gmVr7hQh/YIa4C2A Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmWwAWcACgkQJNaLcl1U h9COVQf/a705pbZzwJ+u2yYjjQXP3ai6RIMlH0LuxLO1/fEdLadBHlLc7PIbq/c1 e1ObAegI5TXMIvKnpiuUg/uBv2ona5Vw5uXxyxqw5P5mvh66oZeC/t4N24jJ1lzX UafQyWkRLbSPrEQSK3ydTOm424O8wiPvAHmppXmCh+ApOtq0wExwLF0QtxCnURPj SSs/qqTWSHZOeeGvv0H3mMvoYHV8bjckc4vd+0W8O5XRM54cHkKS7gl3dhqKk8dV 48qeLfcdLVg2kwnOA6ezy0uOdKWhwCXrRDans4id5epvMu8JRV3T7W50tLX99pw0 3hvF/Zv+EM0ZhHcjZxiBLWoGDedfCQ== =DePV -----END PGP SIGNATURE----- --gmVr7hQh/YIa4C2A--