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 6F1E74963DA; Wed, 29 Jul 2026 13:43:24 +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=1785332605; cv=none; b=ixsCPTKeGkPFZfLikqir2xy8M0qwfjMdifMtD0B2DHqZlWyeHJrZnajz7Rjhac2XmHBpn/KXQtuniBeTDco+AQQ9CH8TvX8QAyO5Mb2m+WNV4S/9F3oeoyUTPPoLqfrrUUaWhRLRtHoVpB8n4mO01mVmhBwPPGvLpQhha2NHITI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785332605; c=relaxed/simple; bh=z6ml+ytMiolfBSIN0QtR8EmUgQ25fO6ycUJNluIIBdU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=dgN6OWAx+d78AJe9yXyyaeupBa4MhSG5anw7IGciRBeE4l7zQNe5rIlXPFE7WIkTSQmy6Y0p9JYyb4m8JfwqoIOdbvKzkYaRyJJLKaxVYWX0QlGygZUHmmODSmHmKj5Q/G2pf/9IeTiYtKJabP1IwNwifEWXkK33OfmAXGlqNi4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZjSuoLL6; 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="ZjSuoLL6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F2E941F00A3A; Wed, 29 Jul 2026 13:43:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785332604; bh=PRcOiNq2tBTTPhKJmq+v2axNzroqRGfQ2NZU0eu9iKE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ZjSuoLL6lpaRqLc85ZT3LkyZzM0Zuhm/g6IAhMNxznnUHr+a6rLolhSNoCEWi/+XP +k6HCNUh4cSAi9zyCrMgJ02jlIO4nJcZUm5LakKUb3pjQbfw2JjFATqCogerkzUdKu 5DtyggnyhvqVRAqVowYb9SwgJsscKYOfSP0OGJxeg/F1x0agvlho4n9YPqdCoWkemo MSUrVc5OGlX5iUIMSdxmUF1lEVhqvsf443v/uXJD/wWFWvdytJ7kBBF2MY6kC6xMH4 hz2vLPNLN8qVdzpXNXCPMplDRgGhhamfwAgPHf3JuXPd6eVIuScvxjfLlZ57xhK8HX Dias68Gw4/HNw== Date: Wed, 29 Jul 2026 06:43:22 -0700 From: Drew Fustini To: Paul Walmsley Cc: Guo Ren , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Arnd Bergmann , Chen Wang , Inochi Amaoto , Leonardo Bras , Raj Vishwanathan4 , Djordje Todorovic , Alexandre Ghiti , Han Gao , Yao Zi , Xiaoguang Xing , Aleksandar Rikalo , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, sophgo@lists.linux.dev Subject: Re: [PATCH V5] riscv: errata: Add ERRATA_THEAD_WRITE_ONCE fixup Message-ID: References: <20260421143154.1590156-1-guoren@kernel.org> 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: On Tue, Jun 02, 2026 at 10:08:09AM -0700, Drew Fustini wrote: > On Tue, Apr 21, 2026 at 10:31:40AM -0400, guoren@kernel.org wrote: > > From: "Guo Ren (Alibaba DAMO Academy)" > > > > The early version of XuanTie C910 core has a store merge buffer > > delay problem. The store merge buffer could improve the store queue > > performance by merging multi-store requests, but when there are not > > continued store requests, the prior single store request would be > > waiting in the store queue for a long time. That would cause > > significant problems for communication between multi-cores. This > > problem was found on sg2042 & th1520 platforms with the qspinlock > > lock torture test. > > > > So appending a fence w.o could immediately flush the store merge > > buffer and let other cores see the write result. > > > > This will apply the WRITE_ONCE errata to handle the non-standard > > behavior via appending a fence w.o instruction for WRITE_ONCE(). > > > > This problem is only observed on the sg2042 hardware platform by > > running the lock_torture test program for half an hour. The problem > > was not found in the user space application, because interrupt can > > break the livelock. > > > > Acked-by: Arnd Bergmann > > Reviewed-by: Alexandre Ghiti > > Reviewed-by: Leonardo Bras > > Reviewed-by: Inochi Amaoto > > Tested-by: Han Gao > > Tested-by: Yao Zi > > Cc: Chen Wang > > Cc: Xiaoguang Xing > > Cc: Paul Walmsley > > Signed-off-by: Guo Ren (Alibaba DAMO Academy) > > --- > > Changelog > > > > v5: > > - Add Acked-by: Arnd Bergmann for asm/generic > > - Add Reviewed-by: Inochi Amaoto > > - Rebase on v7.0 > > Hi Paul, > > Han Gao (revy) let me know that there is now an errata entry for 'Writes > might stick in C910/C920v1 store buffer for too long' [1]. > > Does that address the concern you had about documenting the errata? > > Thanks, > Drew > > [1] https://github.com/revyos/xuantie-c900-bugs#writes-might-stick-in-c910c920v1-store-buffer-for-too-long Hi Paul, could this be considered for the upcoming merge window? Thanks, Drew