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/MWAIT > 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 in > 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
