Re: [PATCH] interrupt preemption support

Gregory Haskins
2007-03-19T14:09:33Z

>>> On Mon, Mar 19, 2007 at 10:03 AM, in message <45FE9827.5030200-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
> Avi Kivity wrote:
>> Gregory Haskins wrote:
>>> Hi Avi,
>>> You make good points. I will convert to a nest lock design and
>>> resubmit. Should I use two mutexes, or a mutex and spinlock?
>>>
>>> Also, do you have any suggestions on the signum I should use to IPI
>>> the running guest? Should I use one of the normal signals (SIGUSR)
>>> or should I start a block of defined signals in the RT range (>32)?
>>>
>>
>> For a short term solution, where the apic is in userspace, we can just
>> say ipi == signal, and not require any locking. Qemu will catch the
>> signal and call the appropriate apic function. The signal number
>> should be set from userspace.
>>
>
> Note that as long as the apic code is in userspace, the sending side is
> also in userspace, so all the IPI related stuff doesn't touch the kernel.

I see. So really the entire approach I took (against the kernel code) is wrong, and I should focus on the QEMU side?

-Greg