On Thu, 2015-08-06 at 13:54 +0800, Chenhui Zhao wrote: > On Thu, Aug 6, 2015 at 1:46 PM, Scott Wood <scottw...@freescale.com> > wrote: > > On Thu, 2015-08-06 at 12:20 +0800, Chenhui Zhao wrote: > > > On Thu, Aug 6, 2015 at 10:57 AM, Scott Wood > > > <scottw...@freescale.com> > > > wrote: > > > > On Wed, 2015-08-05 at 18:11 +0800, Chenhui Zhao wrote: > > > > > On Tue, Aug 4, 2015 at 4:26 AM, Scott Wood > > > <scottw...@freescale.com> > > > > > wrote: > > > > > > On Mon, 2015-08-03 at 19:32 +0800, Chenhui Zhao wrote: > > > > > > > > > > > > > > > > > > > > > On Sat, Aug 1, 2015 at 7:59 AM, Scott Wood > > > > > <scottw...@freescale.com> > > > > > > > wrote: > > > > > > > > > > > > > > > > > > > > > > Could you explain irq_mask()? Why would there still be > > > IRQs > > > > > > > destined > > > > > > > > for > > > > > > > > this CPU at this point? > > > > > > > > > > > > > > This function just masks irq by setting the registers in > > > RCPM > > > > > (for > > > > > > > example, RCPM_CPMIMR, RCPM_CPMCIMR). Actually, all irqs to > > > > > this CPU > > > > > > > have been migrated to other CPUs. > > > > > > > > > > > > So why do we need to set those bits in RCPM? Is it just > > > caution? > > > > > > > > > > Setting these bits can mask interrupts signalled to RCPM from > > > MPIC > > > > > as a > > > > > means of > > > > > waking up from a lower power state. So, cores will not be > > > waked up > > > > > unexpectedly. > > > > > > > > Why would the MPIC be signalling those interrupts if they've been > > > > masked at > > > > the MPIC? > > > > > > > > -Scott > > > > > > > > > > The interrupts to RCPM from MPIC are IRQ, Machine Check, NMI and > > > Critical interrupts. Some of them didn't be masked in MPIC. > > > > What interrupt could actually happen to a sleeping cpu that this > > protects > > against? > > > > -Scott > > Not sure. Maybe spurious interrupts or hardware exceptions.
Spurious interrupts happen due to race conditions. They don't happen because the MPIC is bored and decides to ring a CPU's doorbell and hide in the bushes. If by "hardware exceptions" you mean machine checks, how would such a machine check be generated by a core that is off? > However, setting them make sure dead cpus can not be waked up unexpectedly. I'm not seeing enough value here to warrant resurrecting the old sleep node stuff. -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
