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

["Michael S. Tsirkin" <mst@redhat.com>]

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?

> index 1753a02..8fbdefc 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -2934,7 +2934,7 @@ were needed.
>  
>  \subsection{Device configuration layout}\label{sec:Device Types / Network Device / Device configuration layout}
>  
> -Three configuration fields are currently defined. The \field{mac} address field
> +Three driver-read-only configuration fields are currently defined. The \field{mac} address field
>  always exists (though is only valid if VIRTIO_NET_F_MAC is set), and
>  \field{status} only exists if VIRTIO_NET_F_STATUS is set. Two
>  read-only bits (for the driver) are currently defined for the status field:
> @@ -3339,12 +3339,9 @@ contains multicast addresses.
>  
>  The VIRTIO_NET_CTRL_MAC_ADDR_SET command is used to set the
>  default MAC address which rx filtering
> -accepts.
> +accepts (and if VIRTIO_NET_F_MAC_ADDR has been negotiated,
> +this will be reflected in \field{mac} in config space).
>  
> -Depending on whether VIRTIO_NET_F_MAC_ADDR has been negotiated,
> -\field{mac} in config space or the VIRTIO_NET_CTRL_MAC_ADDR_SET
> -is used to set the default MAC address which rx filtering
> -accepts.
>  The command-specific-data for VIRTIO_NET_CTRL_MAC_ADDR_SET is
>  the 6-byte MAC address.
>  
> @@ -3365,15 +3362,6 @@ nor the MAC filtering table.
>  
>  \drivernormative{\subparagraph}{Setting MAC Address Filtering}{Device Types / Network Device / Device Operation / Control Virtqueue / Setting MAC Address Filtering}
>  
> -A driver MUST NOT write to the \field{mac} if VIRTIO_NET_F_MAC_ADDR is
> -negotiated.
> -
> -The
> -VIRTIO_NET_CTRL_MAC_ADDR_SET command is atomic whereas
> -\field{mac} in config space is not, therefore drivers
> -MUST negotiate VIRTIO_NET_F_MAC_ADDR if they change
> -mac address when device is accepting incoming packets.
> -
>  The driver MUST follow the VIRTIO_NET_CTRL_MAC_TABLE_SET command
>  by a le32 number, followed by that number of non-multicast
>  MAC addresses, followed by another le32 number, followed by