[Qemu-devel] Re: [PATCH 19/41] virtio: use the right types for VirtQueue elements

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Dec 02, 2009 at 07:24:12PM +0100, Juan Quintela wrote:
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > On Wed, Dec 02, 2009 at 01:04:17PM +0100, Juan Quintela wrote:
> >> 
> >> Signed-off-by: Juan Quintela <quintela@redhat.com>
> >> ---
> >>  hw/virtio.c |    8 ++++----
> >>  1 files changed, 4 insertions(+), 4 deletions(-)
> >> 
> >> diff --git a/hw/virtio.c b/hw/virtio.c
> >> index fd617ff..2b36cad 100644
> >> --- a/hw/virtio.c
> >> +++ b/hw/virtio.c
> >> @@ -646,8 +646,8 @@ void virtio_save(VirtIODevice *vdev, QEMUFile *f)
> >>      qemu_put_sbe32s(f, &vdev->num_pci_queues);
> >> 
> >>      for (i = 0; i < vdev->num_pci_queues; i++) {
> >> -        qemu_put_be32(f, vdev->vq[i].vring.num);
> >> -        qemu_put_be64(f, vdev->vq[i].pa);
> >> +        qemu_put_be32s(f, &vdev->vq[i].vring.num);
> >> +        qemu_put_be64s(f, &vdev->vq[i].pa);
> >>          qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
> >>          if (vdev->type == VIRTIO_PCI &&
> >>              virtio_pci_msix_present(vdev->binding_opaque)) {
> >> @@ -703,8 +703,8 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f)
> >>      qemu_get_sbe32s(f, &vdev->num_pci_queues);
> >> 
> >>      for (i = 0; i < vdev->num_pci_queues; i++) {
> >> -        vdev->vq[i].vring.num = qemu_get_be32(f);
> >> -        vdev->vq[i].pa = qemu_get_be64(f);
> >> +        qemu_get_be32s(f, &vdev->vq[i].vring.num);
> >> +        qemu_get_be64s(f, &vdev->vq[i].pa);
> >>          qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
> >> 
> >>          if (vdev->type == VIRTIO_PCI &&
> >
> > Why are these the right types?
> > I see:
> > static inline void qemu_put_be64s(QEMUFile *f, const uint64_t *pv)
> > {
> >     qemu_put_be64(f, *pv);
> > }
> >
> > so passing a pointer to qemu_get_be64s seems exactly equivalent to
> > qemu_put_be64 on value.
> >
> > What am I missing?
> 
> While I was porting this to vmstate, it was difficult.  vmstate always
> use the pointer functions (the other ones shouldn't have been defined at
> all, but that is another war).
> 
> It just made the change to vmstate obvious.  I had to redo it several
> times until it worked :(
> 
> Later, Juan.

Maybe try explaining this in commit log.

-- 
MST