diff options
Diffstat (limited to 'content.tex')
| -rw-r--r-- | content.tex | 17 |
1 files changed, 17 insertions, 0 deletions
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 |