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Diffstat (limited to 'introduction.tex')
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1 files changed, 55 insertions, 31 deletions
diff --git a/introduction.tex b/introduction.tex index 1091911..9b84b5b 100644 --- a/introduction.tex +++ b/introduction.tex @@ -34,37 +34,6 @@ between different transports. acknowledges those it understands and wishes to use. \end{description} -\section{Terminology}\label{Terminology} - -The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in \hyperref[intro:rfc2119]{[RFC2119]}. - -An older specification (see \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}) defined a -similar, but different interface between the hypervisor and the guest. -To simplify transition and note differences, the following terms are used: - -\begin{description} -\item[Legacy Interface] - An interface specified by \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}. -\item[Legacy Device] - A device which implements \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}, but not this specification. -\item[Legacy Driver] - A driver which implements \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}, but not this specification. -\item[Transitional Device] - A device which implements both this specification and the older - \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]} - specification, thus allowing legacy drivers. -\item[Transitional Driver] - A driver which implements both this specification and the older - \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]} - specification, thus allowing legacy devices. -\item[Non-Transitional Device] - A device which does not implement the - \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]} specification. -\item[Non-Transitional Driver] - A driver which does not implement the - \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]} specification. -\end{description} - \section{Normative References} \begin{longtable}{l p{5in}} @@ -100,6 +69,61 @@ To simplify transition and note differences, the following terms are used: \newline\url{http://ozlabs.org/~rusty/virtio-spec/virtio-0.9.5.pdf}\\ \end{longtable} +\section{Terminology}\label{Terminology} + +The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in \hyperref[intro:rfc2119]{[RFC2119]}. + +\subsection{Legacy Interface: Terminology}\label{intro:Legacy +Interface: Terminology} + +Earlier drafts of this specification (i.e. revisions before 1.0, +see e.g. \hyperref[intro:Virtio PCI Draft]{[Virtio PCI Draft]}) +defined a similar, but different +interface between the driver and the device. +Since these are widely deployed, this specification +accommodates OPTIONAL features to simplify transition +from these earlier draft interfaces. + +Specifically devices and drivers MAY support: +\begin{description} +\item[Legacy Interface] + is an interface specified by an earlier draft of this specification + (before 1.0) +\item[Legacy Device] + is a device implemented before this specification was released, + and implementing a legacy interface on the host side +\item[Legacy Driver] + is a driver implemented before this specification was released, + and implementing a legacy interface on the guest side +\end{description} + +Legacy devices and legacy drivers are not compliant with this +specification. + +To simplify transition from these earlier draft interfaces, +a device MAY implement: + +\begin{description} +\item[Transitional Device] + a device supporting both drivers conforming to this + specification, and allowing legacy drivers. +\end{description} + +Similarly, a driver MAY implement: +\begin{description} +\item[Transitional Driver] + a driver supporting both devices conforming to this + specification, and legacy devices. +\end{description} + +\begin{note} + No legacy interfaces are required; ie. don't implement them unless you + have a need for backwards compatibility! +\end{note} + +Devices or drivers with no legacy compatibility are referred to as +non-transitional devices and drivers, respectively. + \section{Structure Specifications} Many device and driver in-memory structure layouts are documented using |