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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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Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 18:10 +0100
  Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 19:50 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 19:50 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Marc Zyngier <marc.zyngier@arm.com> - 2016-02-15 20:00 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 20:00 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Marc Zyngier <marc.zyngier@arm.com> - 2016-02-15 20:10 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 20:20 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-15 20:30 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 20:50 +0100
                Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 21:00 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 20:50 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:30 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:50 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:10 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Russell King - ARM Linux <linux@arm.linux.org.uk> - 2016-02-15 20:10 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 20:10 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 20:50 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 21:00 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-15 21:10 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:40 +0100
          Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' "Rafael J. Wysocki" <rafael@kernel.org> - 2016-02-15 21:40 +0100
            Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Tony Lindgren <tony@atomide.com> - 2016-02-15 22:40 +0100
              Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-16 02:40 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-16 02:20 +0100
      Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace timers with utilization ...' "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2016-02-16 02:30 +0100
        Re: Crashes in arm qemu emulations due to 'cpufreq: governor:  Replace timers with utilization ...' Viresh Kumar <viresh.kumar@linaro.org> - 2016-02-16 02:40 +0100
  Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Peter Maydell <peter.maydell@linaro.org> - 2016-02-15 23:40 +0100
    Re: Crashes in arm qemu emulations due to 'cpufreq: governor: Replace  timers with utilization ...' Guenter Roeck <linux@roeck-us.net> - 2016-02-16 00:30 +0100

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