On Sun, Apr 10, 2011 at 09:26:26PM +0200, Alexander Graf wrote: > > On 10.04.2011, at 21:25, Aurelien Jarno wrote: > > > On Mon, Apr 04, 2011 at 04:32:10PM +0200, Alexander Graf wrote: > >> The feature bitmap in the s390 virtio machine is little endian. To > >> address for that, we need to bswap the values after reading them out. > >> > >> Signed-off-by: Alexander Graf <ag...@suse.de> > >> --- > >> hw/s390-virtio-bus.c | 4 ++-- > >> 1 files changed, 2 insertions(+), 2 deletions(-) > >> > >> diff --git a/hw/s390-virtio-bus.c b/hw/s390-virtio-bus.c > >> index 58af164..60e0135 100644 > >> --- a/hw/s390-virtio-bus.c > >> +++ b/hw/s390-virtio-bus.c > >> @@ -223,7 +223,7 @@ void s390_virtio_device_sync(VirtIOS390Device *dev) > >> cur_offs += num_vq * VIRTIO_VQCONFIG_LEN; > >> > >> /* Sync feature bitmap */ > >> - stl_phys(cur_offs, dev->host_features); > >> + stl_phys(cur_offs, bswap32(dev->host_features)); > > > > Is bswap32 correct here for both big and little endian guests? I don't > > really understand the reason why a bswap is needed here, especially > > given that AFAIK this code was already used when using KVM. > > This is target specific code. The s390-virtio-bus is s390 specific. And yes, > the code was also broken with KVM. That's how I first found it actually. >
So in short, s390-virtio-bus is specific to big endian machines, but is using little endian? That looks a bit weired. I guess it's probably to late to change the specification anyway... -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net http://www.aurel32.net
