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authormstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2015-03-15 10:07:13 +0000
committermstsirkin <mstsirkin@0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652>2015-03-15 10:07:13 +0000
commit4e0739635b32261aea9c05c17081a20be7c00cb6 (patch)
tree850efbcb5c536c9bad35dc2fd24acdbced1f0f0e
parentdb517375409ca452cdb80f6b8f82b349424f36cd (diff)
ccw: allow WRITE_STATUS to fail
We want to be able to fail setting a status on the device (e.g. FEATURES_OK if the device can't work with the features negotiated). The easiest way to do that is to allow the device to fail the WRITE_STATUS command by posting a command reject. VIRTIO-116 Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com> Approved unanimously: https://www.oasis-open.org/apps/org/workgroup/virtio/ballot.php?id=2762 Signed-off-by: Michael S. Tsirkin <mst@redhat.com> git-svn-id: https://tools.oasis-open.org/version-control/svn/virtio/branches/v1.0@479 0c8fb4dd-22a2-4bb5-bc14-6c75a5f43652
-rw-r--r--conformance.tex2
-rw-r--r--content.tex17
2 files changed, 19 insertions, 0 deletions
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