Re: In kernel PIC support: kernel patch

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Gregory Haskins wrote:
> On Fri, 2007-06-22 at 13:50 +0300, Avi Kivity wrote:
>   
>> Dong, Eddie wrote:
>>
>>     
>>> +#include "kvm.h"
>>> +#include "virq.h"
>>> +
>>> +/*
>>> + * check if there is pending interrupt without
>>> + * intack.
>>> + */
>>> +int cpu_has_interrupt(struct kvm_vcpu *v)
>>> +{
>>> +	struct pic_state2 *s = kernel_pic(v->kvm);
>>> +
>>>   
>>>       
>> Isn't the PIC connected to just one cpu?
>>     
>
> I agree with Eddie here.  Its true that only one CPU would ever
> associate with PIC (and its usually hardwired to the BSP, but it
> technically doesn't have to be depending on the architecture).  But the
> PIC(s) are really a system wide resource that should hang off the kvm
> struct, IMHO.
>
> In fact, my own implementation puts the ISA-userint model as hanging off
> the kvm structure as well (which would be replaced with a similar PIC
> model for layer-2 mode in the future).
>
>   

The PIC is certainly a system resource, but at least in qemu it's 
connected to cpu 0 only. We want to preserve that.

I guess it doesn't really matter because smp configurations will use the 
ioapic.


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