On Sun, 24 Nov 2019 07:14:20 -0500
"Michael S. Tsirkin" <> wrote:
> Document as used by Linux.
>
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/59
> Signed-off-by: Michael S. Tsirkin <>
> ---
>
> changes from v2
> - address comments by Cornelia
> - fix more typos
> - consistent upper/lower case for hex values
> - explicitly ask that devices use 0xffffffff for unknown speed
> (this is what Linux uses)
>
>
> content.tex | 33 +++++++++++++++++++++++++++++++++
> 1 file changed, 33 insertions(+)
>
> diff --git a/content.tex b/content.tex
> index bff80d0..678afbe 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -2892,6 +2892,7 @@ \subsection{Feature bits}\label{sec:Device Types / Network Device / Feature bits
>
> \item[VIRTIO_NET_F_STANDBY(62)] Device may act as a standby for a primary
> device with the same MAC address.
> +\item[VIRTIO_NET_F_SPEED_DUPLEX(63)] Device reports speed and duplex.
> \end{description}
>
> \subsubsection{Feature bit requirements}\label{sec:Device Types / Network Device / Feature bits / Feature bit requirements}
> @@ -2951,12 +2952,27 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device
> VIRTIO_NET_F_MTU is set. This field specifies the maximum MTU for the driver to
> use.
>
> +The following two fields, \field{speed} and \field{duplex}, only
> +exist if VIRTIO_NET_F_SPEED_DUPLEX is set.
> +
> +\field{speed} contains the device speed, in units of 1 MByte, 0
> +to 0x7ffffffff, or 0xfffffffff for unknown speed.
> +
> +\field{duplex} has the values of 0x00 for full duplex, 0x01 for
> +half duplex and 0xff for unknown duplex state.
> +
> +Neither \field{speed} not \field{duplex} changes as long as
s/not/nor/
> +VIRTIO_NET_S_LINK_UP is set.
> +
> \begin{lstlisting}
> struct virtio_net_config {
> u8 mac[6];
> le16 status;
> le16 max_virtqueue_pairs;
> le16 mtu;
> + le32 speed;
> + u8 duplex;
> +
> };
> \end{lstlisting}
>
> @@ -2985,6 +3001,18 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device
> If the driver negotiates the VIRTIO_NET_F_STANDBY feature, the device MAY act
> as a standby device for a primary device with the same MAC address.
>
> +If VIRTIO_NET_F_SPEED_DUPLEX has been negotiated, \field{speed}
> +MUST contain the device speed, in units of 1 MByte, 0 to
> +0x7ffffffff, or 0xfffffffff for unknown.
> +
> +If VIRTIO_NET_F_SPEED_DUPLEX has been negotiated, \field{duplex}
> +MUST have the values of 0x00 for full duplex, 0x01 for half
> +duplex and 0xff for unknown.
s/ and/, or/
> +
> +If VIRTIO_NET_F_SPEED_DUPLEX has been negotiated, the device MUST
> +NOT change the \field{speed} and \field{duplex} fields as long as
> +VIRTIO_NET_S_LINK_UP is set in the \field{status}.
> +
> \drivernormative{\subsubsection}{Device configuration layout}{Device Types / Network Device / Device configuration layout}
>
> A driver SHOULD negotiate VIRTIO_NET_F_MAC if the device offers it.
> @@ -3009,6 +3037,11 @@ \subsection{Device configuration layout}\label{sec:Device Types / Network Device
>
> A driver SHOULD negotiate the VIRTIO_NET_F_STANDBY feature if the device offers it.
>
> +If VIRTIO_NET_F_SPEED_DUPLEX has been negotiated,
> +the driver MUST treat any value of \field{speed} above
> +0x7fffffff as well as any value of \field{duplex} not
> +matching 0x00 or 0x01 as an unknown value.
> +
> \subsubsection{Legacy Interface: Device configuration layout}\label{sec:Device Types / Network Device / Device configuration layout / Legacy Interface: Device configuration layout}
> \label{sec:Device Types / Block Device / Feature bits / Device configuration layout / Legacy Interface: Device configuration layout}
> When using the legacy interface, transitional devices and drivers
Other than the nits above
Reviewed-by: Cornelia Huck <>
