+ Peter Z On Wed, Dec 21, 2011 at 3:37 PM, Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> wrote: > On Wed, Dec 21, 2011 at 05:59:07PM +0800, Barry Song wrote: >> 2011/12/21 Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx>: >> > cpu hotplug is basically totally buggered - the preconditions placed >> > upon the bringup code path are basically impossible to satisfy in any >> > shape or form at the moment. >> > >> > There's the requirement that the secondary CPU is marked online and >> > active before interrupts are enabled for the thread migration stuff >> > to behave correctly. However, this is incompatible with smp_call_function() >> > which will wait for online CPUs to respond to an IPI - which this one >> > won't because interrupts are disabled. >> > >> > I think there was some discussion about how to fix this but I don't >> > recall the details. >> >> thanks, Russell. then could i think this is an ARM-kernel-specific bug >> which exists on all ARM SMP chips for the moment? >> and that bug doesn't happen on x86: > > I don't think so. There's nothing ARM specific about it. There are few patches floating around for this issue. I posted one version long back [1] and then there was one more form Thomas G. The most recent is from one is from Peter Z [2] which is moving the fix for the cup online race to core code. Can you try Peter's patch with your test-case ? Regards, Santosh [1] https://lkml.org/lkml/2011/6/20/79 [2] https://lkml.org/lkml/2011/12/15/255 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
