Messages in this thread | | | Date | Fri, 06 Jun 2008 09:12:44 -0700 | From | "H. Peter Anvin" <> | Subject | Re: Recoverable MCA interrupts from NMI handlers? IPMI and RCU? |
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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). >
In theory, recoverable #MC's can occur anywhere. It's an exception.
> 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.
Not sure about that one. I clearly need to look carefully into this... SMI is quite "special" in that it sets up an entirely new environment; the concept of executing kernel code at SMI level makes me want to run away and hide.
-hpa
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