On Thu, 5 Aug 2010, Vaidyanathan Srinivasan wrote: > * Darren Hart <dvh...@us.ibm.com> [2010-08-04 21:45:51]: > > > On 07/23/2010 12:07 AM, Vaidyanathan Srinivasan wrote: > > >* Benjamin Herrenschmidt<b...@kernel.crashing.org> [2010-07-23 15:11:00]: > > > > > >>On Fri, 2010-07-23 at 10:38 +0530, Vaidyanathan Srinivasan wrote: > > >>>Yes. extended_cede_processor() will return with interrupts enabled in > > >>>the cpu. (This is done by the hypervisor). Under normal cases we > > >>>cannot be interrupted because no IO interrupts are routed to us after > > >>>xics_teardown_cpu() and since the CPU is out of the map, nobody will > > >>>send us IPIs. > > >> > > >>What about decrementer ? > > > > > >Decrementer expiry event handling is bit complex. The event as such > > >may not bring back the extended_cede_processor() cpu, but may be > > >marked pending when we get out of this state eventually. I will find > > >more information on this event and update. > > > > Hi Vaidy, have you been able to dig anything up about the > > decrementer expiry? > > Hi Darren, > > Yes, it is possible that the cpu in extended_cede_processor() can be > woken up by the decrementer. But the expectation is that we will > return back to this context since we will not have any pending timers.
The problem is that you might get woken _before_ the timers have been migrated away. > Our stack should not change even if we get the decrementer interrupts. But you should not execute kernel code when you got offlined either. Thanks, tglx _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev