On Wed, Jul 01, 2015 at 03:50:50PM +0200, Michael S. Tsirkin wrote:
On Wed, Jul 01, 2015 at 02:30:29PM +0200, Gerd Hoffmann wrote:
On Mi, 2015-07-01 at 10:08 +0200, Michael S. Tsirkin wrote:
On Tue, Jun 30, 2015 at 10:38:53AM +0200, Gerd Hoffmann wrote:
virtio version 1.0 registers can (and actually do in the qemu implementation) live in mmio space. So we must run the blk and scsi virtio drivers in 32bit mode, otherwise we can't access them.
This also allows to drop a bunch of GET_LOWFLAT calls from the virtio code in the following patches.
Signed-off-by: Gerd Hoffmann kraxel@redhat.com
Is there an advantage to running them in a 16 bit mode?
Not really any more. Switching from 32bit mode back to whatever-was-active-before used to be problematic before we had smm mode support. In theory. Because you can't save/restore the complete x86 processor state. In practice we had surprisingly few problems, appearently linux boot loaders simply don't play dirty tricks.
cheers, Gerd
Interesting. Might not be true for non-linux loaders :)
Anyway we support SSM now so all should be well, right?
Also a question: what's cheaper on kvm: use SMM to save/restore or access device through the config cap?
-- MST