Re: [PATCH] VIRTIO-52: Make mac field read only.

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

"Michael S. Tsirkin" <mst@redhat.com> writes:
> On Mon, May 05, 2014 at 08:07:48PM +0930, Rusty Russell wrote:
>> Signed-off-by: Rusty Russell <rusty@au1.ibm.com>
>
> Hmm ok but legacy drivers want to use VIRTIO_NET_F_MAC so
> I think we should document it as writeable for
> transitional devices in legacy mode.
> Agree?

Oh, indeed.  We talk about writing the mac in legacy mode, but we
should make it explicit.

I also noticed that we talked about legacy drivers which didn't
negotiate VIRTIO_NET_F_MAC_ADDR: we meant VIRTIO_NET_F_CTRL_MAC_ADDR.

This diff on top of previous:

diff --git a/content.tex b/content.tex
index 8fbdefc..6a9cc02 100644
--- a/content.tex
+++ b/content.tex
@@ -2983,6 +2983,9 @@ MUST format \field{status} and
 according to the native endian of the guest rather than
 (necessarily when not using the legacy interface) little-endian.
 
+When using the legacy interface, \field{mac} is driver-writable
+which provided a way for drivers to update the MAC without
+negotiating VIRTIO_NET_F_CTRL_MAC_ADDR.
 
 \subsection{Device Initialization}\label{sec:Device Types / Network Device / Device Initialization}
 
@@ -3373,7 +3376,7 @@ MUST format \field{entries} in struct virtio_net_ctrl_mac
 according to the native endian of the guest rather than
 (necessarily when not using the legacy interface) little-endian.
 
-Legacy drivers that didn't negotiate VIRTIO_NET_F_MAC_ADDR
+Legacy drivers that didn't negotiate VIRTIO_NET_F_CTRL_MAC_ADDR
 changed \field{mac} in config space when NIC is accepting
 incoming packets. These drivers always wrote the mac value from
 first to last byte, therefore after detecting such drivers,