Re: Fwd: Re: [PATCH] Add irqdevice interface + userint implementation

["Gregory Haskins" <ghaskins-Et1tbQHTxzrQT0dZR+AlfA@public.gmane.org>]

>>> On Tue, Apr 10, 2007 at 12:11 PM, in message <461BB738.7040206-atKUWr5tajBWk0Htik3J/w@public.gmane.org>,
Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote: 
>
>
> It's more complex than that; 

Isn't it always ;)

> you need to program the hardware to exit on 
> a specific threshold level of tpr values (e.g. exit when tpr <= n).
> 

Agreed, but don't forget the TPR/CR8 will always be an exposed interface of the LAPIC and therefore readily available for factoring into the algorithm.  I just am not there yet.

> It's a little sad to encode a complex condition (wait for nmi window 
> opening/wait for irq window opening/wait for irq window opening with tpr 
> <= n) in irqdevice, then decode it in the vcpu and program the hardware 
> accordingly.

Agreed, but keep in mind that whatever we make the irqdevice do, it will have to do it in both the QEMU and in-kernel models if we want true dynamic ABI support for old userspace.  I was trying to reduce the duplication of code in each model, but perhaps it's no more complex either way...TBD. 

Regards,
-Greg



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