On Fri, Dec 04, 2015 at 02:34:52PM -0800, Andy Lutomirski wrote: > On Fri, Dec 4, 2015 at 9:53 AM, Luck, Tony <[email protected]> wrote: > > ist_enter() is black magic to me. Andy? Would you be worried about executing > > ist_{enter,exit}() on a cpu that was once online, but is currently marked > > offline > > by Linux? > > Offline CPUs are black magic to me. But as long as the CPU works the > way that the normal specs say it should, then ist_enter is fair game. > In any event, if context tracking blows up on an offline CPU, I'd > argue that's a context tracking bug and needs to be fixed. > > But maybe offlined CPUs are supposed to have all interrupts off > (including MCE?) and the argument goes the other way? Dunno.
MCE's are broadcast by the hardware and cannot be blocked. Offline is only a Linux specific state. Now if the offline was a result of an ACPI event (eject) that triggered the CPU removal (offline in Linux, as it would have in a platform that supports true hotplug) then the platform would remove this cpu from the broadcast list. if kernel were to set CR4.MCE=0 that would cause system shutdown when an MCE is broadcast and hits this cpu. Cheers, Ashok -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
