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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-369e8afd64fsm1007158eec.0.2026.10.23.14.26.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2026 14:26:26 -0700 (PDT) Date: Fri, 23 Oct 2026 14:26:21 -0700 From: Jonathan Cameron To: Pierre Gondois , Tony Luck , Borislav Petkov Cc: linux-kernel@vger.kernel.org, James Morse , Mark Brown , "Rafael J. Wysocki" , Len Brown , Mauro Carvalho Chehab , Shuai Xue , Maciej Wieczor-Retman , Pawel Chmielewski , Dave Jiang , "Fabio M. De Francesco" , Breno Leitao , Dan Williams , Terry Bowman , Ard Biesheuvel , Morduan Zang , linux-acpi@vger.kernel.org, linux-edac@vger.kernel.org, acpica-devel@lists.linux.dev, Ashok Raj Subject: Re: [PATCH v2 0/6] CPER: Add Memory Error Section 2 support Message-ID: <20261023142621.00007051@oss.qualcomm.com> In-Reply-To: <0817615d-5e96-4a3a-b39e-3e5d1b88e716@arm.com> References: <20261019203915.2019037-1-pierre.gondois@arm.com> <20261020101048.00000186@oss.qualcomm.com> <0817615d-5e96-4a3a-b39e-3e5d1b88e716@arm.com> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Info: AW1haW4tMjYxMDIzMDA4NCBTYWx0ZWRfXyrektTYqdY0x pp8gXE/0WnKJhxxg0Ysjke6ANfr/RY+HymDrJDwYHpyGRueJVYq5oqsNFvMGjGb15ys3MPmxzN4 2ULWANq1xu66ZZl3vZcnu19D0bo9qNk= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDIzMDA4NCBTYWx0ZWRfX3WyOo02Fdfdt URuSUofBeQLyY3GhcTR0xQqaIVqkOtUOltvRYHtKQj3hsJylI8aRVnbKxJak88ug9QwOKTrXNrX KF4sVoQv57tYGroNM5aY/JfHjptzR4WkOA3cUwsJ5K2nHl2+jIrG/i3l7bJ6K5Y5DUs6yPzpHSL xcvTd3/x6RSw6V65hnWxdkzzjwnsJNzBLgbv9UxHSe9VJIWRrzsRcuPLUmB4YAOq/UX3AfTS5s2 BRAndFOgaFeBbsJ2CrMDNeHcfhtG53jhEgkQHulJbo0mcO5P1lepkXpAiVW99MQ5alOAEIroc6I G6lP2M86qQ2pPgp2ZoMXjJSV4H/k02I85mqP1Y5zWcsR53rKd3O80y88JGtDmHr8NwGk0l92rrC 2hGnwh4bU0xoaJTsSW8FY8eqaVxu1DChA4ai1vF7+sN5I+j+TI22XCoeqAsmKY8nhObrYthHclY 5HGFTexpbCWff3n5qEA== X-Authority-Analysis: v=2.4 cv=Ju5kP84C c=1 sm=1 tr=0 ts=6adbd105 cx=c_pps a=cFYjgdjTJScbgFmBucgdfQ==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_K5XuSEh1TEqbUxoQ0s3:22 a=7CQSdrXTAAAA:8 a=viUReOrFISyjNDj8nWYA:9 a=CjuIK1q_8ugA:10 a=scEy_gLbYbu1JhEsrz4S:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-GUID: MS3ISfAgKzH99u3BMIbf76pjDgq1q7Ok X-Proofpoint-ORIG-GUID: MS3ISfAgKzH99u3BMIbf76pjDgq1q7Ok X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.138,FMLib:17.12.100.49 definitions=2026-10-23_05,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 spamscore=0 impostorscore=0 suspectscore=0 phishscore=0 clxscore=1015 adultscore=0 priorityscore=1501 lowpriorityscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610190000 definitions=main-2610230084 On Thu, 22 Oct 2026 09:07:25 +0200 Pierre Gondois wrote: > On 10/20/26 19:10, Jonathan Cameron wrote: > > On Mon, 19 Oct 2026 22:38:39 +0200 > > Pierre Gondois wrote: > > > >> The support is mostly duplicated from Memory Error Section handling. > >> Other than differences coming from the content of Memory Error > >> Section 1 and 2, differences in the support are: > >> > >> - v2 do not rely on a compact "struct cper_mem_err_compact" struct. > >> This structure was used to support older versions of the Memory > >> Error Section (1). This is not needed for the new structure. > >> > >> - The compact version is also used by the tracing framework. > >> To avoid relying and propagating a non-standard record format, > >> through trace event (cf. extlog_mem event) the new trace event > >> prints each field individually. > >> > >> The last patch of the serie was only build-tested due to the > >> absence of relevant hardware. apei_mce_report_mem_error() and > >> arch_apei_report_mem_error() implementations were also removed since > >> last version. > >> > >> It will also require a proper handling from the rasdaemon. Applying > >> this last patch without rasdaemon support will silent the reports of > >> Memory Error Section 2 error, cf. ras_userspace_consumers() check. > > Hi Pierre, > > > > I'd slow down a bit. We are mid merge window and convention is normally > > one version a week or so anyway. Better to gather up feedback from > > a number of folk and spin only one revision to cover it all. > > > Hello Jonathan, > > Ok sure, as the v1 was reviewed quickly I thought there was a chance > of having the serie accepted quickly aswell. I ll wait a bit more. > > Thanks for the review, > > Pierre > A general question that came up in a related thread with one of our RAS architects. How does firmware decide what to send? As far as I can tell firwmare has no way to know whether the OS understands the CPER Memory Section 2. So options that come to mind. 1. Firmware must send a CPER with both Memory Section and Memory Section 2. 2. For whatever other reason a platform knows it doesn't work with old kernel so can assume support in kernel and hopefully userspace got updated too. 3. We propose some additional discoverability (quickly - code first) to ACPI so that it can be a negotiated contract between OS and firmware. Until the OS confirms it understands Memory Section 2, firmware has to send the older one (or risk the record not being understood). After that negotiation it can do what it likes - probably send the Memory Section 2 form. Option 1 and 2 are ugly at best. Obvious path to me for option 3 is an _OSC like the one for generic initiators that we discovered a need for whilst implementing that years ago. Anyhow have a better idea? The above doesn't solve the end to end problem as maybe userspace still has no idea what this new tracepoint is, but at least gets us past hop 1 (so through the kernel). If we conclude _OSC plan works I'll draft a code first proposal. Jonathan