Re: [virtio] [OASIS Issue Tracker] Created: (VIRTIO-7) Reserve device ID 0 (zero) as invalid

[Rusty Russell <rusty@au1.ibm.com>]

OASIS Issues Tracker <workgroup_mailer@lists.oasis-open.org> 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 <rusty@au1.ibm.com>
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 <rusty@au1.ibm.com>

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.
+
 2.5.1 Network Device
 ====================