On Tue, 2013-08-20 at 07:44 +0100, Rusty Russell wrote:
> OASIS Issues Tracker <> writes:
> > Reserve device ID 0 (zero) as invalid
> > -------------------------------------
> >
> > Key: VIRTIO-7
> > URL: http://tools.oasis-open.org/issues/browse/VIRTIO-7
> > Project: OASIS Virtual I/O Device (VIRTIO) TC
> > Issue Type: Improvement
> > Reporter: Pawel Moll
> >
> >
> > Make the virtio device ID 0 reserved (or illegal). This value is illegal for PCI devices anyway, and mmio driver can consider such ID as "non present".
>
> Something like this?
>
> commit d8a995390a273bc6d209cf8a6f8a178b424a6438
> Author: Rusty Russell <>
> Date: Tue Aug 20 16:13:19 2013 +0930
>
> Reserve device ID 0 (zero) as invalid
>
> See http://tools.oasis-open.org/issues/browse/VIRTIO-7
>
> Signed-off-by: Rusty Russell <>
>
> diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt
> index 8fc96b2..f989630 100644
> --- a/virtio-v1.0-wd01-part1-specification.txt
> +++ b/virtio-v1.0-wd01-part1-specification.txt
> @@ -1069,6 +1069,8 @@ Discovering what devices are available and their type is bus-dependent.
> | Device ID | Virtio Device |
> +------------+--------------------+
> +------------+--------------------+
> +| 0 | none (ignore) |
> ++------------+--------------------+
> | 1 | network card |
> +------------+--------------------+
> | 2 | block device |
> @@ -1094,6 +1096,8 @@ Discovering what devices are available and their type is bus-dependent.
> | 12 | virtio CAIF |
> +------------+--------------------+
>
> +When a device is discovered with a device ID of 0, it should be ignored.
How about:
0 reserved (invalid)
No device will ever have an ID of 0 (zero). Transports may choose to
ignore such devices.
