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Diffstat (limited to 'content.tex')
| -rw-r--r-- | content.tex | 54 |
1 files changed, 4 insertions, 50 deletions
diff --git a/content.tex b/content.tex index cb0d648..c9a566a 100644 --- a/content.tex +++ b/content.tex @@ -98,61 +98,15 @@ which was not offered. The device SHOULD accept any valid subset of features the driver accepts, otherwise it MUST fail to set the FEATURES_OK \field{device status} bit when the driver writes it. -\subsection{Legacy Interface: A Note on transitions from earlier drafts}\label{sec:Basic Facilities of a Virtio Device / Feature Bits / Legacy Interface: A Note on transitions from earlier drafts} - -%TODO: split out conformance sections -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. - -\begin{note} - No legacy interfaces are required; ie. don't implement them unless you - have a need for backwards compatibility! -\end{note} - -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} - -Devices or drivers with no legacy compatibility are referred to as -non-transitional devices and drivers, respectively. +\subsection{Legacy Interface: A Note on Feature +Bits}\label{sec:Basic Facilities of a Virtio Device / Feature +Bits / Legacy Interface: A Note on Feature Bits} Transitional Drivers MUST detect Legacy Devices by detecting that the feature bit VIRTIO_F_VERSION_1 is not offered. Transitional devices MUST detect Legacy drivers by detecting that VIRTIO_F_VERSION_1 has not been acknowledged by the driver. + In this case device is used through the legacy interface. Legacy interface support is OPTIONAL. |