Re: [Qemu-devel] Re: [PATCH 26/35] kvm: Eliminate KVMState arguments

[Avi Kivity]

On 01/11/2011 04:36 PM, Anthony Liguori wrote:
> > They need to use the same device id then.  And if they share code, 
> > that indicates that they need to be the same device even more.
>
>
> No, it really doesn't :-)  Cirrus VGA and std VGA share a lot of 
> code.  But that doesn't mean that we treat them as one device.

Cirrus and VGA really are separate devices.  They share code because on 
evolved from the other, and is backwards compatible with the other.  
i8254 and i8254-kvm did not evolve from each other, both are 
implementations of the i8254 spec, and both are 100% compatible with 
each other (modulu bugs).

> And BTW, there are guest visible differences between the KVM 
> IOAPIC/PIC/PIT than the QEMU versions.  The only reason PIT live 
> migration works today is because usually delivers all interrupts 
> quickly.  But it actually does maintain state in the work queue that 
> isn't saved.  If PIT tried to implement gradual catchup, there would 
> be no way not to expose that state to userspace.

Why not?  Whatever state the kernel keeps, we expose to userspace and 
allow sending it over the wire.


--
error compiling committee.c: too many arguments to function