On Thu, 12 Jun 2014 11:43:20 +0200
Alexander Graf <ag...@suse.de> wrote:
>
> On 12.06.14 11:39, Paolo Bonzini wrote:
> > Il 12/06/2014 11:37, Michael S. Tsirkin ha scritto:
> >> Maybe just drop unnecessary stuff for new machine types?
> >> Then we won't need hacks to migrate it.
> >
> > For any machine type it's trivial to migrate it. All machine types
> > including old ones can disregard the migrated values.
>
> How about a patch like this before the actual LE awareness ones? With
> this we should make virtio-serial config space completely independent of
> live migration.
>
> Also since QEMU versions that do read these swapped values during
> migration are not bi-endian aware, we can never get into a case where a
> cross-endian save needs to be considered ;).
>
>
> Alex
>
>
> diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
> index 2b647b6..73cb9b7 100644
> --- a/hw/char/virtio-serial-bus.c
> +++ b/hw/char/virtio-serial-bus.c
> @@ -670,6 +670,7 @@ static int virtio_serial_load(QEMUFile *f, void
> *opaque, int version_id)
> uint32_t max_nr_ports, nr_active_ports, ports_map;
> unsigned int i;
> int ret;
> + uint32_t tmp;
>
> if (version_id > 3) {
> return -EINVAL;
> @@ -685,17 +686,12 @@ static int virtio_serial_load(QEMUFile *f, void
> *opaque, int version_id)
> return 0;
> }
>
> - /* The config space */
> - qemu_get_be16s(f, &s->config.cols);
> - qemu_get_be16s(f, &s->config.rows);
> -
> - qemu_get_be32s(f, &max_nr_ports);
> - tswap32s(&max_nr_ports);
> - if (max_nr_ports > tswap32(s->config.max_nr_ports)) {
> - /* Source could have had more ports than us. Fail migration. */
> - return -EINVAL;
> - }
> + /* Unused */
> + qemu_get_be16s(f, &tmp);
> + qemu_get_be16s(f, &tmp);
> + qemu_get_be32s(f, &tmp);
>
> + max_nr_ports = tswap32(s->config.max_nr_ports);
> for (i = 0; i < (max_nr_ports + 31) / 32; i++) {
> qemu_get_be32s(f, &ports_map);
>
>
For the moment, we have 0 < max_nr_ports < 32 so the source
machine only stores a single 32 bit value... If this limit
gets raised, we can end up sending more than that... and
only the source machine max_nr_ports value can give the
information...
--
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.
