Re: [Qemu-devel] [RFC PATCH 05/21] target-arm: add CPU Monitor mode

[Fedorov Sergey]

On 12/04/2013 03:18 PM, Peter Maydell wrote:
> On 4 December 2013 10:58, Peter Crosthwaite
> <address@hidden> wrote:
> > So what im proposing is just a slightly more general patch. Is it
> > really any more complicated than just applying your change pattern for
> > the hyp mode?
> I think it would be, because of the wrinkle that hyp mode doesn't
> have a banked LR, so the existing "assume we can just translate
> the mode into a single index good for both LR and SP" logic
> would break.
>
> The minimal change if we wanted to keep VMSD bumps to a
> minimum would be to increase the size of the banked_spsr[]
> and banked_r13[] arrays to allow for Hyp mode but do nothing
> else (except add a comment about it I guess).

If we want to bump VMSD just once for monitor + hypervisor mode then we 
need to add ELR_hyp register definition too. I think then it would be 
better to implement hypervisor mode and its special banking scheme, too. 
But I doubt it worth to combine these two things into one patch.

> > The motiviation is less VMSD version bumps in ARM CPU (a place where I
> > expect assume such version bumps to be considerable annoyance).
> Well, they're only a problem at the point where we start trying
> to support cross-version migration; we're not at that point yet...
>
> thanks
> -- PMM

Best regards,
Sergey Fedorov