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[199.106.103.254]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36a42935b4asm13643226eec.16.2026.10.30.14.40.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 14:40:16 -0700 (PDT) Date: Fri, 30 Oct 2026 14:40:13 -0700 From: Jonathan Cameron To: Pierre Gondois Cc: Ashok Raj , Mauro Carvalho Chehab , Tony Luck , Borislav Petkov , 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: <20261030144013.0000320e@oss.qualcomm.com> In-Reply-To: References: <20261019203915.2019037-1-pierre.gondois@arm.com> <20261020101048.00000186@oss.qualcomm.com> <0817615d-5e96-4a3a-b39e-3e5d1b88e716@arm.com> <20261023142621.00007051@oss.qualcomm.com> <20261024003917.283b890d@foz.lan> <20261023170405.000060b8@oss.qualcomm.com> <43301529-f169-493c-bc59-fa08b77e1ef3@arm.com> <20261030081941.000040e7@oss.qualcomm.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-Details-Enc: AW1haW4tMjYxMDMwMDA4NiBTYWx0ZWRfX/o3gFp6K9SWO vmBoWB9YlqeE9h+zoAEwrrX1+Xg8//lsnb4X1Qw02YYTGyA2YHnyWEhuuuBj2oX8ib1EagdRhfa KJewseJBgrEWYVxeZ/LQLuny0sDfJsReVTmsLCulgGhWq1zW64ivtMkELlCIhq3F2v1GAC0TUI6 EpegJ82Zz63uGak80Cng9nCDOd4rZLPtxQ/mxRglTQ+FNskRKzQaQovRNwGYL12kPgSrF2AiYoI 7r1uyETdlQU4g9SVZcPpuv5Bn1sMaR86iJn/awk4Cm51910mQH32kFVXj0t3N7VeYK5keNgOTGi 6wnPUQR90orX3sNrRlb5QaS5DowjpFR4N7GCGASk53i3PXHbPzeZPKyVEv5lVWU7kmcjCdgSdcn TkDKEp3u+JWVvRGRo4v4Hfl7Y62N5AwB3VUP1gQPayZJbgqXRm+Zu2WNVGRGU92y7O4IDzMkTLX x9GZa+Sjg+3iDc+YKrw== X-Authority-Analysis: v=2.4 cv=CLG/zhrD c=1 sm=1 tr=0 ts=6ae50ec2 cx=c_pps a=wEP8DlPgTf/vqF+yE6f9lg==:117 a=JYp8KDb2vCoCEuGobkYCKw==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=7CQSdrXTAAAA:8 a=OkvmfuOBzfRrInaeso0A:9 a=CjuIK1q_8ugA:10 a=bBxd6f-gb0O0v-kibOvt:22 a=a-qgeE7W1pNrGK8U0ZQC:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDMwMDA4NiBTYWx0ZWRfXzCJQvQheE+16 3DRWqW/XwzD6V7BG0j2DOifuSmvK5OasNvTZNhwJZhu+Uyjg6lYAgs4PT5jrZAwvXBncg6ejuhS T7/uOTV0pcGoiunocWY3ssXbuGz7pUM= X-Proofpoint-GUID: N9d88DvelQGZqZ285piRw0Uji97rXop_ X-Proofpoint-ORIG-GUID: N9d88DvelQGZqZ285piRw0Uji97rXop_ 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=2026-10-30_06,2026-10-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 suspectscore=0 clxscore=1015 phishscore=0 priorityscore=1501 impostorscore=0 adultscore=0 lowpriorityscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610300000 definitions=main-2610300086 On Fri, 30 Oct 2026 18:16:06 +0100 Pierre Gondois wrote: > On 10/30/26 16:19, Jonathan Cameron wrote: > > On Fri, 30 Oct 2026 12:51:47 +0100 > > Pierre Gondois wrote: > > > >> On 10/25/26 00:05, Ashok Raj wrote: > >>> On Fri, Oct 23, 2026 at 05:04:05PM -0700, Jonathan Cameron wrote: > >>>> On Sat, 24 Oct 2026 00:40:33 +0200 > >>>> Mauro Carvalho Chehab wrote: > >>>> > >>>>> On Fri, 23 Oct 2026 14:26:21 -0700 > >>>>> Jonathan Cameron wrote: > >>>>> > >>>>>> 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. > >>>>> Please don't do this: this would require either Kernespace or userspace to > >>>>> discard one of the reports, only if the other one is there, which can be > >>>>> tricky. Could be done more easily at userspace, but only if some database > >>>>> support is enabled, but, at least on rasdaemon, this is an optional module. > >>>> Good. That confirms my view that is horrible. > >>> Hi Jonathan, > >>> > >>> I agree that an _OSC capability is the right long-term solution. > >>> > >>> Firmware should select one native CPER format based on OS support, rather > >>> than emit both Section 1 and Section 2 and leave deduplication to the OS > >>> or userspace. > >>> > >>> For a Section 2-capable kernel, we may still avoid a second GHES notifier > >>> chain: preserve the existing struct cper_sec_mem_err * contract and give > >>> it a lossy Section 1 projection of a Section 2 record. The conversion must > >>> translate validation bits and clear validity for values that cannot be > >>> represented, rather than truncate them. > >> I understand we might want to emit a new extlog_mem2_event and a lossy > >> extlog_mem_event for legacy userspace, but I'm not sure to follow how > >> you want to do it. > >> > >> Do you suggest that we only need one notifier (ghes_report_mem_chain) > >> and that we should not add ghes_report_mem2_chain ? This would mean > >> that the .notifier_call (= ghes_edac_report_mem_error) should handle > >> both cper_sec_mem_err/cper_sec_mem_err2 struct. > >> > >> Another solution would be to keep the ghes_report_mem2_chain, > >> which would be responsible of creating the lossy v1 struct and > >> triggering the original ghes_report_mem_chain. > >> > >>> That preserves legacy EDAC consumers, but cannot carry all Section 2 data. > >>> Updated userspace needs the native Section 2 payload through a > >>> full-fidelity path, such as the existing GUID-tagged raw CPER event. > >>> > >>> This does mean an updated userspace listener may receive both the legacy > >>> EDAC summary and the raw Section 2 record for the same firmware error. > >>> They are two kernel views, not two firmware reports. We should therefore > >>> add a shared GHES record/section ID to both events, so userspace can > >>> correlate them reliably; address and timestamp are not sufficient. > >>> > >>> So _OSC solves firmware selection for old versus new kernels, while a > >>> Section 1 projection plus the raw payload handles legacy versus updated > >>> consumers on a new kernel. > >>> > >>> Thoughts? > >> This will put more burden on the firmware, but this seems the right > >> thing to do. I ll share the thread with the group working more closely > >> on the architecture aswell, > > We have will have a code first proposal for the _OSC part shortly. Just going > > through internal review. I'll make sure you + others here are on the +CC. > > Ok thanks, > If you can also also add Mark Brown > https://lore.kernel.org/linux-acpi/20261030143802.0000231d@oss.qualcomm.com/ I started a new thread so it wasn't too buried. Thanks Jonathan