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| -rw-r--r-- | conformance.tex | 2 | ||||
| -rw-r--r-- | content.tex | 17 |
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diff --git a/conformance.tex b/conformance.tex index 29c6ba8..59193e9 100644 --- a/conformance.tex +++ b/conformance.tex @@ -79,6 +79,7 @@ A Channel I/O driver MUST conform to the following normative statements: \begin{itemize} \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Basic Concepts} \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision} +\item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information} \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host->Guest Notification / Notification via Adapter I/O Interrupts} \item \ref{drivernormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest->Host Notification} \end{itemize} @@ -182,6 +183,7 @@ A Channel I/O device MUST conform to the following normative statements: \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Basic Concepts} \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting the Virtio Revision} \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue} +\item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information} \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Setting Up Indicators / Setting Up Two-Stage Queue Indicators} \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Host->Guest Notification / Notification via Adapter I/O Interrupts} \item \ref{devicenormative:Virtio Transport Options / Virtio over channel I/O / Device Operation / Guest->Host Notification} diff --git a/content.tex b/content.tex index 6a8638b..1efe93a 100644 --- a/content.tex +++ b/content.tex @@ -2595,6 +2595,23 @@ The driver changes the status of a device via the CCW_CMD_WRITE_STATUS command, which transmits an 8 bit status value. +As described in +\ref{devicenormative:Basic Facilities of a Virtio Device / Feature Bits}, +a device sometimes fails to set the \field{status} field: For example, it +might fail to accept the FEATURES_OK status bit during device initialization. + +\drivernormative{\paragraph}{Communicating Status Information}{Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information} + +If the device posts a unit check with command reject in response to the +CCW_CMD_WRITE_STATUS command, the driver MUST assume that the device failed +to set the status and the \field{status} field retained its previous value. + +\devicenormative{\paragraph}{Communicating Status Information}{Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information} + +If the device fails to set the \field{status} field to the value written by +the driver, the device MUST assure that the \field{status} field is left +unchanged and MUST post a unit check with command reject. + \subsubsection{Handling Device Features}\label{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Handling Device Features} Feature bits are arranged in an array of 32 bit values, making |