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Subject: Re: [PATCH v4] clarify device reset
On Thu, 28 Jan 2021 14:52:35 +0100 Cornelia Huck <cohuck@redhat.com> wrote: > Properly specify that the method for the driver to request a > device reset is transport specific, and some action the device > has to take. Fixes: https://github.com/oasis-tcs/virtio-spec/issues/93 > > 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
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