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I see what you mean. > > > > Do we really need this rule? It is essentially the same as the following > > rule: > > > > MCESEV( > > PANIC, "In kernel and no restart IP", > > EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0) > > ), > > > > ...since we assume "KERNEL" context if RIPV|EIPV are clear after > > checking the CS register. > > I'm not sure this could ever happen. But if it did, I think I'd like > to see that message. > > > > The message is not as explicit though. > > > > I did have an earlier idea that we introduce an "UNKNOWN" context for > > the !pt_regs case. > > > > We could add the "UNKNOWN" context to the "Neither restart nor error IP" > > rule. That way it'll be skipped if we have a "USER" context and then it > > should match the one you want. > > I don't want to do that anywhere execpt that Sandybridge instruction > fetch case (which wasn't classified as an erratum, because the h/w > guys chose to set RIPV==0 and EIPV==0 ... but it was a poor choice.) > > > Also, I just saw this in the Intel SDM: > > > > "For the P6 family processors, if the EIPV flag in the MCG_STATUS MSR is > > set, the saved contents of CS and EIP registers are directly associated > > with the error that caused the machine-check exception to be generated; > > if the flag is clear, the saved instruction pointer may not be associated > > with the error (see Section 17.3.1.2, “IA32_MCG_STATUS MSR”)." > > > > But I can't tell if this is true just for P6 or all, because the CS > > register isn't referenced again with EIPV. > > Should probably have said "P6 and newer". The intent of EIPV is to > indicate that this machine check is because of something that happened > on the current CPU (remember this bit was defined when all #MC on Intel > were broadcast, so knowing which CPU(s) are involved, and which have > just been pulled in to the #MC handler by the broadcast was very > important. > Okay, fair enough. It seems like these quirks should stay. Thanks for the discussion. It really helped me better understand these quirks and their history. Thanks, Yazen