Re: [Qemu-devel] [PATCH 3/5] x86: fill high bits of mtrr mask

[Paolo Bonzini]

On 16/06/2016 22:14, Eduardo Habkost wrote:
> This is necessary only when phys_bits is higher on the
> destination, right?
> 
> Should we really default this to true? I would like to enable
> this hack only when really necessary. Except when using host's
> phys_bits (phys-bits=0), is there any valid reason to expect
> higher phys-bits on the destination?

It would need a property even if you did it only for phys-bits==0, and
then it's simpler to just do it always.

The bits are reserved anyway, so we can do whatever we want with them.
In fact I think it's weird for the architecture to make them
must-be-zero, it might even make more sense to make them must-be-one...
It's a mask after all, and there's no way to access out-of-range
physical addresses.

Paolo