On Thu, 17 Oct 2013 14:23:35 +1030 Rusty Russell <ru...@rustcorp.com.au> wrote:
> This is a re-transmit of the core of the virtio endian code. Since > there seems to be some interest in ARM BE virtio, I've separated this from > the direct problem I was solving: PowerPC LE. > > Please apply! > Rusty. > > Rusty Russell (7): > virtio_get_byteswap: function for endian-ambivalent targets using > virtio. > virtio: allow byte swapping for vring and config access > hw/net/virtio-net: use virtio wrappers to access headers. > hw/net/virtio-balloon: use virtio wrappers to access page frame > numbers. > hw/block/virtio-blk: use virtio wrappers to access headers. > hw/scsi/virtio-scsi: use virtio wrappers to access headers. > hw/char/virtio-serial-bus: use virtio wrappers to access headers. Hi Rusty! May I ask what's the current status of your virtio endian patches? We likely need something similar when we enable Virtio v1.0 for S390 virtio-ccw since we then have to byteswap the virtio stuff there, too. So I recently started to have a look at this... However, in your patches, the byteswapping seems to be activated/disabled globally, with the "virtio_byteswap" variable. But with Virtio v1.0, the guest can decide on a per-device basis whether it wants to drive the device in v1.0 mode (--> byteswap on S390) or in v0.9 legacy mode (--> no byteswap), depending on whether it sets the VIRTIO_F_VERSION_1 feature bit or not. I guess other architectures will have the same problem with Virtio 1.0, too, when the guests are not running in little endian mode. So I wonder whether it would it be feasible to change the code so that the decision of byteswapping or not is done on a per-device basis instead? What do you think? Regards, Thomas
