Re: VIRTIO - compatibility with different virtualization solutions

[Rusty Russell <rusty@au1.ibm.com>]

Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> writes:
> On Fri, Feb 21, 2014 at 10:05:06AM +0000, Wei Liu wrote:
>> On Thu, Feb 20, 2014 at 06:50:59PM -0800, Anthony Liguori wrote:
>> > The standard should say, "physical address"
>
> This conversation is heading towards - implementation needs it - hence lets
> make the design have it. Which I am OK with - but if we are going that
> route we might as well call this thing 'my-pony-number' because I think
> each hypervisor will have a different view of it.
>
> Some of them might use a physical address with some flag bits on it.
> Some might use just physical address.
>
> And some might want an 32-bit value that has no correlation to to physical
> nor virtual addresses.

True, but if the standard doesn't define what it is, it's not a standard
worth anything.  Xen is special because it's already requiring guest
changes; it's a platform in itself and so can be different from
everything else.  But it still needs to be defined.

At the moment, anything but guest-phys would not be compliant.  That's a
Good Thing if we simply don't know the best answer for Xen; we'll adjust
the standard when we do.

Cheers,
Rusty.