Re: [Qemu-devel] QEMU ARM SMP: IPI delivery delayed until next main loop event // how to improve IPI latency?

[Peter Maydell]

On 15 June 2015 at 21:03, Alex Zuepke <address@hidden> wrote:
> Am 15.06.2015 um 20:58 schrieb Peter Maydell:
>> I'm beginning to suspect that your guest code has a race
>> condition in it, such that if the other CPU runs at a
>> point you weren't expecting it to then you end up
>> deadlocking or otherwise running into a bug in your guest.
>>
>> In particular, I see the emulation getting stuck even without
>> this patch to arm_cpu_set_irq().

> Yes, it's a bug, sorry for that. I removed too much code to get a simple
> testcase. It's stuck in the first spinlock where CPU#1 is waiting for CPU#0
> to initialize the rest of the system, and I need to WFE or YIELD here as
> well.
>
> But this is showing the original problem again: the emulation get's stuck
> spinning on CPU #1 forever, because the main loop doesn't switch to CPU #0
> voluntarily. Just press a key on the console/emulated serial line to trigger
> an event to QEMU's main loop, and the testcase should continue.

Pressing a key does not unwedge the test case for me.

-- PMM