Re: [Qemu-devel] [PATCH v2 0/7] APIC/IOAPIC cleanup

[malc]

On Thu, 19 Aug 2010, Anthony Liguori wrote:

> On 08/19/2010 04:21 PM, Blue Swirl wrote:
> > > Should CPUs appear in the QEMU device tree?
> > >      
> > They have several properties that should be user visible.
> >    
> 
> Sure, but that's an argument for having some of the qdev features (like
> variant properties) be consumable outside of qdev.
> 

[..snip..]

> 
> Yes, but the programming model was different.
> 
> Look at the PIC compared to the lapic.  The PIC is programmed via pio at a
> fixed location.  There is only one PIC and it interacts with the system just
> like all other devices.  IOW, there is no reference to CPUState.

There are two PICs actually there's a cascade..

> 
> When you look at the local APIC (apic.c) however, you see that it's the only
> device in the tree that actually interacts with a CPUState.  The notion of
> cpu_get_current_apic() is a good example of the tricks needed to make this
> work.
> 
> The local APIC is a cpu feature, not a device.
> 
> Regards,
> 
> Anthony Liguori
> 

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