Re: [Qemu-devel] [PATCH v4] virtio dataplane: adapt dataplane for virtio Version 1

[Stefan Hajnoczi <stefanha@redhat.com>]

On Wed, Sep 02, 2015 at 06:53:44PM +0200, Pierre Morel wrote:
> +    addr = virtio_queue_get_desc_addr(vdev, n);
> +    size = virtio_queue_get_desc_size(vdev, n);
> +    ptr = vring_map(&vring->mr_desc, addr, size, true);
> +    if (!ptr) {
> +        error_report("Failed to map 0x%16lx byte for vring desc at %16lx",
> +                      size, addr);
> +        goto out_err_desc;
>      }
> -
> -    vring_init(&vring->vr, virtio_queue_get_num(vdev, n), vring_ptr, 4096);
> +    vr->desc = ptr;
> +
> +    addr = virtio_queue_get_avail_addr(vdev, n);
> +    size = virtio_queue_get_avail_size(vdev, n);
> +    size += sizeof(__virtio16);

Please add a comment explaining what these 2 bytes are for.

> +    ptr = vring_map(&vring->mr_avail, addr, size, true);
> +    if (!ptr) {
> +        error_report("Failed to map 0x%16lx byte for vring avail at %16lx",
> +                      size, addr);
> +        goto out_err_avail;
> +    }
> +    vr->avail = ptr;
> +
> +    addr = virtio_queue_get_used_addr(vdev, n);
> +    size = virtio_queue_get_used_size(vdev, n);
> +    size += sizeof(__virtio16);

Here too.