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Diffstat (limited to 'content.tex')
| -rw-r--r-- | content.tex | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/content.tex b/content.tex index 20a61d6..d6cafc6 100644 --- a/content.tex +++ b/content.tex @@ -4787,23 +4787,27 @@ if VIRTIO_F_VERSION_1 is not accepted. \section{Legacy Interface: Reserved Feature Bits}\label{sec:Reserved Feature Bits / Legacy Interface: Reserved Feature Bits} -Legacy or transitional devices may offer the following: - +Transitional devices MAY offer the following: \begin{description} -\item[VIRTIO_F_NOTIFY_ON_EMPTY (24)] Negotiating this feature - indicates that the driver wants an interrupt if the device runs +\item[VIRTIO_F_NOTIFY_ON_EMPTY (24)] If this feature + has been negotiated by driver, the device MUST issue + an interrupt if the device runs out of available descriptors on a virtqueue, even though interrupts are suppressed using the VRING_AVAIL_F_NO_INTERRUPT flag or the \field{used_event} field. \begin{note} - An example of this is the + An example of a driver using this feature is the legacy networking driver: it doesn't need to know every time a packet is transmitted, but it does need to free the transmitted packets a finite time after they are transmitted. It can avoid using a timer if the device interrupts it when all the packets are transmitted. \end{note} +\end{description} +Transitional devices MUST offer, and if offered by the device +traditional drivers MUST negotiate the following: +\begin{description} \item[VIRTIO_F_ANY_LAYOUT (27)] This feature indicates that the device accepts arbitrary descriptor layouts, as described in Section \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing / Legacy Interface: Message Framing}. |