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Diffstat (limited to 'content.tex')
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1 files changed, 25 insertions, 3 deletions
diff --git a/content.tex b/content.tex index c577133..4147467 100644 --- a/content.tex +++ b/content.tex @@ -263,8 +263,20 @@ these parts (following \ref{sec:Basic Facilities of a Virtio Device / Split Virt \end{note} +Two formats are supported: Split Virtqueues (see \ref{sec:Basic +Facilities of a Virtio Device / Split +Virtqueues}~\nameref{sec:Basic Facilities of a Virtio Device / +Split Virtqueues}) and Packed Virtqueues (see \ref{sec:Basic +Facilities of a Virtio Device / Packed +Virtqueues}~\nameref{sec:Basic Facilities of a Virtio Device / +Packed Virtqueues}). + +Every driver and device supports either the Packed or the Split +Virtqueue format, or both. + \input{split-ring.tex} +\input{packed-ring.tex} \chapter{General Initialization And Device Operation}\label{sec:General Initialization And Device Operation} We start with an overview of device initialization, then expand on the @@ -5215,10 +5227,15 @@ Currently these device-independent feature bits defined: \begin{description} \item[VIRTIO_F_RING_INDIRECT_DESC (28)] Negotiating this feature indicates that the driver can use descriptors with the VIRTQ_DESC_F_INDIRECT - flag set, as described in \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table / Indirect Descriptors}. - + flag set, as described in \ref{sec:Basic Facilities of a Virtio +Device / Virtqueues / The Virtqueue Descriptor Table / Indirect +Descriptors}~\nameref{sec:Basic Facilities of a Virtio Device / +Virtqueues / The Virtqueue Descriptor Table / Indirect +Descriptors} and \ref{sec:Packed Virtqueues / Indirect Flag: Scatter-Gather Support}~\nameref{sec:Packed Virtqueues / Indirect Flag: Scatter-Gather Support}. \item[VIRTIO_F_RING_EVENT_IDX(29)] This feature enables the \field{used_event} - and the \field{avail_event} fields as described in \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression} and \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring}. + and the \field{avail_event} fields as described in +\ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Interrupt Suppression}, \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Used Ring} and \ref{sec:Packed Virtqueues / Driver and Device Event Suppression}. + \item[VIRTIO_F_VERSION_1(32)] This indicates compliance with this specification, giving a simple way to detect legacy devices or drivers. @@ -5228,6 +5245,9 @@ Currently these device-independent feature bits defined: addresses in memory. If this feature bit is set to 0, then the device emits physical addresses which are not translated further, even though an IOMMU may be present. + \item[VIRTIO_F_RING_PACKED(34)] This feature indicates + support for the packed virtqueue layout as described in + \ref{sec:Basic Facilities of a Virtio Device / Packed Virtqueues}~\nameref{sec:Basic Facilities of a Virtio Device / Packed Virtqueues}. \end{description} \drivernormative{\section}{Reserved Feature Bits}{Reserved Feature Bits} @@ -5241,6 +5261,8 @@ passed to the device into physical addresses in memory. If VIRTIO_F_IOMMU_PLATFORM is not offered, then a driver MUST pass only physical addresses to the device. +A driver SHOULD accept VIRTIO_F_RING_PACKED if it is offered. + \devicenormative{\section}{Reserved Feature Bits}{Reserved Feature Bits} A device MUST offer VIRTIO_F_VERSION_1. A device MAY fail to operate further |