Messages in this thread | | | Date | Fri, 6 Jun 2008 14:33:45 -0700 | From | "Paul E. McKenney" <> | Subject | Re: Recoverable MCA interrupts from NMI handlers? IPMI and RCU? |
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On Fri, Jun 06, 2008 at 03:53:00PM -0500, Corey Minyard wrote: > Paul E. McKenney wrote: > >Hello! > > > >A couple of questions about the x86 architecture... > > > >1. Can recoverable machine-check exceptions occur from within > > NMI handlers? If so, there is a bug in preemptable RCU's > > CONFIG_NO_HZ handling that could be fixed by a patch something > > like the one shown below (untested, probably does not even > > compile). > > > >2. Does the IPMI subsystem make use of RCU read-side primitives > > from within SMI handlers? If so, we need the SMI handlers to > > invoke rcu_irq_enter() upon entry and rcu_irq_exit() upon exit > > when they are invoked from dynticks idle state. Or something > > similar, depending on restrictions on code within SMI handlers. > > > If you mean the IPMI driver, it does not tie into any SMI. It > theoretically could since there's a bit for that in the watchdog timer, > but there's been no demand and I haven't looked at it. I guess it would > be better than an NMI. > > If it did tie in, it would most likely just panic to get useful > information out before the watchdog reset the system.
Thanks for the info! I will stop worrying about SMIs and RCU, then.
Thanx, Paul
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