virtio: simplify config mechanism.

Previously we used a type/len pair within the config space, but this
seems overkill.  We now simply define a structure which represents the
layout in the config space: the config space can now only be extended
at the end.

The main driver-visible changes:
1) We indicate what fields are present with an explicit feature bit.
2) Virtqueues are explicitly numbered, and not in the config space.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 7 insertions, 4 deletions

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index ae469ae55d36..6e8fdfea8cd0 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -5,16 +5,19 @@
 /* The ID for virtio_net */
 #define VIRTIO_ID_NET   1
 
-/* The bitmap of config for virtio net */
-#define VIRTIO_CONFIG_NET_F     0x40
+/* The feature bitmap for virtio net */
 #define VIRTIO_NET_F_NO_CSUM    0
 #define VIRTIO_NET_F_TSO4       1
 #define VIRTIO_NET_F_UFO        2
 #define VIRTIO_NET_F_TSO4_ECN   3
 #define VIRTIO_NET_F_TSO6       4
+#define VIRTIO_NET_F_MAC        5
 
-/* The config defining mac address. */
-#define VIRTIO_CONFIG_NET_MAC_F 0x41
+struct virtio_net_config
+{
+        /* The config defining mac address (if VIRTIO_NET_F_MAC) */
+        __u8 mac[6];
+} __attribute__((packed));
 
 /* This is the first element of the scatter-gather list.  If you don't
  * specify GSO or CSUM features, you can simply ignore the header. */