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Subject: [PATCH v4] clarify device reset
Properly specify that the method for the driver to request a device reset is transport specific, and some action the device has to take. Signed-off-by: Cornelia Huck <cohuck@redhat.com> --- Stefan, Halil: I did not apply your R-b due to the amount of changes. v3 -> v4: - moved device status 're-initialize to 0' clause that is now duplicated to an informal description - more clarifications on when reset may be used and device requirements - use \field{device status} consistently RFC v2 -> v3: - re-worded the "must not send notifications" clause to avoid guessing - added a driver conformance clause on how a driver should find out when reset is complete RFC -> RFC v2: - moved reset spec to basic facilities --- conformance.tex | 2 ++ content.tex | 24 +++++++++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/conformance.tex b/conformance.tex index e78adfdbd283..17c390d249db 100644 --- a/conformance.tex +++ b/conformance.tex @@ -64,6 +64,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets} \begin{itemize} \item \ref{drivernormative:Basic Facilities of a Virtio Device / Device Status Field} \item \ref{drivernormative:Basic Facilities of a Virtio Device / Feature Bits} +\item \ref{drivernormative:Basic Facilities of a Virtio Device / Device Reset} \item \ref{drivernormative:Basic Facilities of a Virtio Device / Device Configuration Space} \item \ref{drivernormative:Basic Facilities of a Virtio Device / Virtqueues} \item \ref{drivernormative:Basic Facilities of a Virtio Device / Message Framing} @@ -283,6 +284,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets} \begin{itemize} \item \ref{devicenormative:Basic Facilities of a Virtio Device / Device Status Field} \item \ref{devicenormative:Basic Facilities of a Virtio Device / Feature Bits} +\item \ref{devicenormative:Basic Facilities of a Virtio Device / Device Reset} \item \ref{devicenormative:Basic Facilities of a Virtio Device / Device Configuration Space} \item \ref{devicenormative:Basic Facilities of a Virtio Device / Message Framing} \item \ref{devicenormative:Basic Facilities of a Virtio Device / Virtqueues / The Virtqueue Descriptor Table} diff --git a/content.tex b/content.tex index 1ca24c13f2d0..47239b877c6c 100644 --- a/content.tex +++ b/content.tex @@ -51,6 +51,9 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev an error from which it can't recover. \end{description} +The \field{device status} field starts out as 0, and is reinitialized to 0 by +the device during reset. + \drivernormative{\subsection}{Device Status Field}{Basic Facilities of a Virtio Device / Device Status Field} The driver MUST update \field{device status}, setting bits to indicate the completed steps of the driver @@ -71,7 +74,6 @@ \section{\field{Device Status} Field}\label{sec:Basic Facilities of a Virtio Dev \end{note} \devicenormative{\subsection}{Device Status Field}{Basic Facilities of a Virtio Device / Device Status Field} -The device MUST initialize \field{device status} to 0 upon reset. The device MUST NOT consume buffers or send any used buffer notifications to the driver before DRIVER_OK. @@ -193,6 +195,26 @@ \section{Notifications}\label{sec:Basic Facilities of a Virtio Device terminology. Occasionally, the term event is used to refer to a notification or a receipt of a notification. +\section{Device Reset}\label{sec:Basic Facilities of a Virtio Device / Device Reset} + +The driver may want to initiate a device reset at various times; notably, +it is required to do so during device initialization and device cleanup. + +The mechanism used by the driver to initiate the reset is transport specific. + +\devicenormative{\subsection}{Device Reset}{Basic Facilities of a Virtio Device / Device Reset} + +A device MUST reinitialize \field{device status} to 0 after receiving a reset. + +A device MUST NOT send notifications or interact with the queues after +indicating completion of the reset by reinitializing \field{device status} +to 0, until the driver re-initializes the device. + +\drivernormative{\subsection}{Device Reset}{Basic Facilities of a Virtio Device / Device Reset} + +The driver SHOULD consider a driver-initiated reset complete when it +reads \field{device status} as 0. + \section{Device Configuration Space}\label{sec:Basic Facilities of a Virtio Device / Device Configuration Space} Device configuration space is generally used for rarely-changing or -- 2.26.2
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