On Wed, 2011-11-09 at 14:38 +0200, Avi Kivity wrote: > On 11/09/2011 10:46 AM, Sasha Levin wrote: > > > Alternatively we can add new structures with new > > > structure IDs, pointed to from PCI configuration space. > > > > > > As we don't yet have devices or drivers with 64 bit features, > > > I decided we don't need high feature bits in legacy space. > > > This also frees up feature bit 31 as we don't need it > > > to enable high feature bits anymore. > > > > KVM tool actually has support for 64bit features, we can probably remove > > that when Pekka isn't looking :) > > > > What about the Windows drivers? While 64-bit features were defined, there was no actual devices to use them. So even if Windows drivers had the ability to support 64-bit features, no device ever needed it therefore no device ever activated it. A potential issue might arise when we remap feature bit 31 to do something else, and when activated it would fool Windows drivers to think that 64-bit features are now activated, while they're not - but thats not something that should happen since legacy layout shouldn't have that field enabled as per the spec (no new features in legacy code). I was unable to check if it was actually implemented in the drivers because http://git.kernel.org/?p=virt/kvm/kvm-guest-drivers-windows.git;a=summary is not quite there (*cough*). -- Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
