Messages in this thread | | | Date | Mon, 15 Feb 2016 19:07:00 +0000 | From | Russell King - ARM Linux <> | Subject | Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' |
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On Mon, Feb 15, 2016 at 07:54:26PM +0100, Rafael J. Wysocki wrote: > On Mon, Feb 15, 2016 at 7:49 PM, Marc Zyngier <marc.zyngier@arm.com> wrote: > > Given that OMAP3 is a UP system, there is zero chance that it has > > registered the magic hook that delivers IPIs (its interrupt controller > > is not even capable of doing so). > > > > I don't really know the context, but IPIs on a UP system seem at best odd. > > That would explain it, thanks. > > So it looks like we should always use irq_work_queue() on UP even if > CONFIG_SMP is set, shouldn't we?
irq_work_queue_on() doesn't check whether 'cpu' is the CPU that we're running on. This is a problem where we want to be able to run a kernel built for SMP on a UP system.
I guess the question is whether irq_work_queue_on() is buggy, or whether our implementation of arch_send_call_function_single_ipi() is buggy. Should arch_send_call_function_single_ipi() do something on UP systems, if so what?
We don't have IPIs on UP systems, so we can't raise any interrupts. So, should we call generic_smp_call_function_interrupt() directly from it?
Some clues would be good...
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