virtio — archive

[Michael S. Tsirkin <mst@redhat.com>]

Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- content.tex 31 +++++++++++++++++++++ ---------- 1 file changed, 21 insertions(+), 10 deletions(-) diff --git a/content.tex b/content.tex index f2f3132..9f01ab0 100644 --- a/content.tex +++ b/content.tex @@ -91,8 +91,9 @@ space. Earlier drafts of this specification (up to 0.9.X) defined a similar, but different interface between the hypervisor and the guest. Since these are widely deployed, this specification -accommodates optional features to simplify transition -from these earlier draft interfaces. Specifically: +accommodates OPTIONAL features to simplify transition +from these earlier draft interfaces. Specifically +devices and drivers MAY support: egin{description} item[Legacy Interface] @@ -110,33 +111,43 @@ Legacy devices and legacy drivers are not compliant with this specification. To simplify transition from these earlier draft interfaces, -it is possible to implement: +a device MAY implement: egin{description} item[Transitional Device] a device supporting both drivers conforming to this specification, and allowing legacy drivers. +end{description} +Similarly, a driver MAY implement: +egin{description} item[Transitional Driver] a driver supporting both devices conforming to this specification, and legacy devices. end{description} -Transitional devices and transitional drivers can be compliant with -this specification (ie. when not operating in legacy mode). - Devices or drivers with no legacy compatibility are referred to as non-transitional devices and drivers, respectively. -Transitional Drivers can detect Legacy Devices by detecting that +Transitional Drivers MUST detect Legacy Devices by detecting that the feature bit VIRTIO_F_VERSION_1 is not offered. -Transitional devices can detect Legacy drivers by detecting that +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. +Thus, both transitional and non-transitional devices and +drivers are compliant with this specification. + To make them easier to locate, specification sections documenting -these transitional features are explicitly marked with 'Legacy -Interface' in the section title. +features limited to transitional devices and transitional drivers +are explicitly marked with 'Legacy Interface' in the section title. + +When device is used through the legacy interface, transitional +devices and transitional drivers MUST operate according to the +requirements documented within these legacy interface sections. +Specification text within these sections generally does not apply +to non-transitional devices. section{Device Configuration Space}label{sec:Basic Facilities of a Virtio Device / Device Configuration Space} -- MST