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 [off-list ref] wrote:

quoted

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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