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 238BD1A5BB1 for ; Tue, 12 Aug 2025 05:46:06 +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=1754977567; cv=none; b=glU6m08V3UuGfS0e6yxX7gbMmSlHvfqfcDtyLIql/uv1ZDTRmLDdYoqAIVQmTLsJ/RAVOxQZBtvptNFgl8s00HK9UWXEuedubjJ5Bp417pRQJpK65N4mxvgXEbK/ejU4+FyrayW8ZAEKtKLBGkYTniXUCjYbWO/bl8RtMmTLagA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754977567; c=relaxed/simple; bh=FMFubZzw5IsK4kYuUJoxjkzx4VzJv3nuhFsuIBFsRLU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Q12KlEYQ3sHnTk3S+TX/CoS2SYF8+aCbTnePnowiYjCg2U4xGMYKXqj7PLOW/62fPAwdl0/fUgN3l4zvGEsO5xdnU7saD/BCiBBKrdvPGKZK+ODbjXItU6DwARbWbtHlZPh+ju/sDRpDaa0gK/yuixffSji721mdLsMoHGbwv5U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=codgUbls; 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="codgUbls" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8DEA5C4CEF0; Tue, 12 Aug 2025 05:46:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754977566; bh=FMFubZzw5IsK4kYuUJoxjkzx4VzJv3nuhFsuIBFsRLU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=codgUbls4Jz8D1XxnqnT/EyunZJUa9myWZ6KM6clwyGUJ6WEPqJZaW8dW1l6LmCR6 HV764gnLlxlkLNykXx4JDVpET2TYITdaH6XLQSdaxoN/nW1/dBEDf8XR19kQ2cukyZ ekOySjByBeQxpGA8jVU8pZ6CH/0uA35Z18MUh1rPKSolwbKqfkaMH41MxfC/sPnvOS BiJBfrVSHpa8b1UFS7xtaTGxczxvZuio7abrv2I8I/sLZdocmAgK1vBX09PB8nT6ZA JCQT9BhD4zK5vNhtkK5VRbofDm9VltutqHmoe4zOsUMZ79btNRR9OV42jsnmEXM6Ce C8dhIXrTcWyJw== Date: Mon, 11 Aug 2025 22:46:05 -0700 From: Drew Fustini To: Vivian Wang Cc: Darius Rad , Paul Walmsley , Palmer Dabbelt , Alexandre Ghiti , Samuel Holland , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Andy Chiu , Conor Dooley , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Drew Fustini Subject: Re: [PATCH v2] riscv: Add sysctl to control discard of vstate during syscall Message-ID: References: <20250806-riscv_v_vstate_discard-v2-1-6bfd61b2c23b@kernel.org> <5a96d08e-0714-4925-a9c4-ea66549623d1@iscas.ac.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a96d08e-0714-4925-a9c4-ea66549623d1@iscas.ac.cn> On Sun, Aug 10, 2025 at 05:52:54PM +0800, Vivian Wang wrote: > > Discarding vector state on syscall entry can help identify userpace > > programs that are mistakenly relying on vector state being preserved > > across syscalls. This can be useful for debugging and test suites. > > However, this behavior can negatively impact performance on some > > RISC-V implementations. > > > > Say Y here if you want mandatory clobbering of vector state before > > entering all syscalls. If you select N, then userspace can still > > eanble it via the abi.riscv_v_vstate_discard sysctl knob. > > Typo: eanble -> enable > > Also, I think it kinda makes the false impression that the sysctl knob > is only available with this set to N? I think this should be structured > to say something like this being the default value, and also say that > userspace can override this behavior system-wide via the sysctl knob. Thanks, that is a good point that I should clarify that the user can still override via the sysctl knob regardless of whether choosing Y or N for this Kconfig option. -Drew