Re: [Qemu-devel] [PATCH bandaid for-1.4] fix virtio-net for win guests

[Anthony Liguori <aliguori@us.ibm.com>]

Michael Tokarev <mjt@tls.msk.ru> writes:

> This is a quick-n-dirty bandaid to let virtio-net to work on windows
> again.  Merely removing newly added stuff (max_virtqueue_pairs)
> from struct virtio_net_config makes fixes it.  Note this field
> of the structure is not actually used, as far as I can see - it
> is write-only, so it shouldn't affect anything, but it lets win
> guests to run with virtio-net and hence allows for wider testing.
>
> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

It's write-only because it's read by the guest.

I just sent a series that should give us a reasonable work around.  I'm
pretty confident that the guest driver is misbehaving.  I don't think
it's reasonable to disable mq by default just because there's a broken
driver out there.

However, with my series, existing guests that are using a fixed machine
model should work with no changes.

Regards,

Anthony Liguori

> ---
>  hw/virtio-net.c |    2 +-
>  hw/virtio-net.h |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> index e37358a..fb6b101 100644
> --- a/hw/virtio-net.c
> +++ b/hw/virtio-net.c
> @@ -102,7 +102,7 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
>      struct virtio_net_config netcfg;
>  
>      stw_p(&netcfg.status, n->status);
> -    stw_p(&netcfg.max_virtqueue_pairs, n->max_queues);
> +//XXX doesnotwork    stw_p(&netcfg.max_virtqueue_pairs, n->max_queues);
>      memcpy(netcfg.mac, n->mac, ETH_ALEN);
>      memcpy(config, &netcfg, sizeof(netcfg));
>  }
> diff --git a/hw/virtio-net.h b/hw/virtio-net.h
> index f5fea6e..faf44c5 100644
> --- a/hw/virtio-net.h
> +++ b/hw/virtio-net.h
> @@ -76,7 +76,7 @@ struct virtio_net_config
>      /* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
>      uint16_t status;
>      /* Max virtqueue pairs supported by the device */
> -    uint16_t max_virtqueue_pairs;
> +//XXXX doesnotwork    uint16_t max_virtqueue_pairs;
>  } QEMU_PACKED;
>  
>  /*
> -- 
> 1.7.10.4