On Wed, 18 Jun 2014 16:42:04 +0300 "Michael S. Tsirkin" <m...@redhat.com> wrote: > On Wed, Jun 18, 2014 at 01:53:15PM +0100, Peter Maydell wrote: > > On 18 June 2014 11:38, Stefan Hajnoczi <stefa...@gmail.com> wrote: > > > What bothers me is that real hardware can't do this. > > > > Real hardware doesn't have "endianness matches guest CPU endianness" > > semantics, which is what the virtio spec mandates... > > So it was buggy. We never thought anyone would do a cross endian CPU :(. > We are fixing it in 1.0. >
virtio isn't the only victim... we also have vga. The problem can pop up anywhere you rely on TARGET_WORDS_BIGENDIAN. > > > Given that VIRTIO > > > 1.0 is always little-endian I guess this is just a temporary hack for > > > ppc little-endian. Would be nice to add a comment so it's clear why > > > this approach is being taken instead of a cleaner solution. > > > > Also for ARM big-endian, and indeed for any CPU with runtime > > configurable endianness that wants to use the kernel virtio > > drivers that exist in the real world rather than the theoretical > > future ones that might some day be written for the 1.0 virtio > > spec... > > > > thanks > > -- PMM > > That's not a theoretical future. > Spec will almost certainly be frozen two weeks from now. > So it is almost certain that drivers will be there in 3.17. > I don't want argue on the dates but I doubt that all legacy users will switch to 1.0 as soon as it shows up... a transition period may be needed. > Existing distros can then simply backport the > drivers - same as they would with any other new hardware. > Are you saying that upstream QEMU should not to support the transition between legacy and 1.0 at all ? Cheers. -- Gregory Kurz kurzg...@fr.ibm.com gk...@linux.vnet.ibm.com Software Engineer @ IBM/Meiosys http://www.ibm.com Tel +33 (0)562 165 496 "Anarchy is about taking complete responsibility for yourself." Alan Moore.