Re: ovmf / PCI passthrough impaired due to very limiting PCI64 aperture

[Guilherme Piccoli]

Thanks Gerd, Dave and Eduardo for the prompt responses!

So, I understand that when we use "-host-physical-bits", we are
passing the *real* number for the guest, correct? So, in this case we
can trust that the guest physbits matches the true host physbits.

What if then we have OVMF relying in the physbits *iff*
"-host-phys-bits" is used (which is the default in RH and a possible
machine configuration on libvirt XML in Ubuntu), and we have OVMF
fallbacks to 36-bit otherwise?

Now, regarding the problem "to trust or not" in the guests' physbits,
I think it's an orthogonal discussion to some extent. It'd be nice to
have that check, and as Eduardo said, prevent migration in such cases.
But it's not really preventing OVMF big PCI64 aperture if we only
increase the aperture _when  "-host-physical-bits" is used_.

Thanks,


Guilherme