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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-kernel@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: AW1haW4tMjYxMDIzMDA4NCBTYWx0ZWRfXza1ChRjWkoXQ Gd1JdoweKwRj1rreCH0QvJngInRYOVRGirki6fil0jyFGTIq9uc3JzMVtpyliSBYEOufzDS1Z6X tfLdFzPZwgZgzJVtx7GB38veN740ZDU= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDIzMDA4NCBTYWx0ZWRfX61x/wBDGyFhN UegNDVzH2VFVIktpI/vS6vXcevcF1YouObVSnKCXsZDzjPDOD2jqfKYzCgCO0aj5IwQeSVUwUek kgNsgpnNEAwCOpmWhSRmQ3U8O75IZDEDsHpCZEoCScFuUgZk/OLo94OjWQv7NO25LXqVxI9nhve V8W8lgru2Gsg1nrqBIc6RaMCgJ6lXq4hTtLOg/uPZukUCp94KRozrJ27tv3S8G+ZK/+W97fd3g1 320XR0XTCulIDXnihwNTLOtMAOth6XTR5eOIAU5j4Qj9wy1dWYjVUz9yw1MPv+NnH9AW+pRatOU cIDlUMF7RSs1KCqegA0ortV7OzKFiohBYrQELcA/qXxGYGxFE37JVCdwNYOF/nOGoRVxlMKpCJ7 MPo30aI1TK1AyTmvIeBLGfABe3OdVU9SFUd1csNzIGrf/0coMNZpKHTOPFm546/hJIMKDPUXmCT q1EXXKc2C6EloRrvssg== X-Authority-Analysis: v=2.4 cv=Ju5kP84C c=1 sm=1 tr=0 ts=6adbd104 cx=c_pps a=Uww141gWH0fZj/3QKPojxA==: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=PxkB5W3o20Ba91AHUih5:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-GUID: nLkxz8sU5cE5upzUHHcVYpYy8577FAY_ X-Proofpoint-ORIG-GUID: nLkxz8sU5cE5upzUHHcVYpYy8577FAY_ 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