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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 25 Apr 2025 12:36:50.3565 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 1311ce3b-5836-40ab-1be7-08dd83f5da0f X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000EDD0.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB8293 On Wed Apr 23, 2025 at 12:32 PM BST, Roger Pau Monne wrote: > There are several errata on Intel regarding the usage of the MONITOR/MWAI= T > instructions, all having in common that stores to the monitored region > might not wake up the CPU. > > Fix them by forcing the sending of an IPI for the affected models. > > The Ice Lake issue has been reproduced internally on XenServer hardware, > and the fix does seem to prevent it. The symptom was APs getting stuck i= n > the idle loop immediately after bring up, which in turn prevented the BSP > from making progress. Ugh... so this is what it was... Awesome having this madness fixed. Do you happen to know if Linux has a similar fix in place? > This would happen before the watchdog was initialized, and hence the > whole system would get stuck. That's nasty. It was the misassumption that the watchdog was already running that had me going in circles thinking it was a lockup rather than a livelock. Oh, well. I believe the kudos for finally being able to reproduce this goes to Frediano? Cheers, Alejandro