diff options
| -rw-r--r-- | content.tex | 31 |
1 files changed, 24 insertions, 7 deletions
diff --git a/content.tex b/content.tex index d43decd..5abc79e 100644 --- a/content.tex +++ b/content.tex @@ -1121,15 +1121,32 @@ cap.length >= queue_notify_off * notify_off_multiplier + 2 \subsubsection{ISR status capability}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / ISR status capability} The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG capability. This -refers to at least a single byte, which contains the 8-bit ISR status field: -\begin{lstlisting} -#define VIRTIO_PCI_ISR_VQ 0x1 -#define VIRTIO_PCI_ISR_CONFIG 0x2 -\end{lstlisting} +refers to at least a single byte, which contains the 8-bit ISR status field. + +The \field{offset} for the ISR status field has no specific alignment requirements. + +The ISR status field is used for INT\#x interrupt handling. +The driver MUST NOT access the ISR field when MSI-X capability +is enabled. + +\begin{tabular}{ |l||l|l|l| } +\hline +Bits & 0 & 1 & 2 to 31 \\ +\hline +Purpose & Device Configuration Interrupt & Queue Interrupt & Reserved \\ +\hline +\end{tabular} + +If MSI-X capability is disabled, device MUST set Interrupt Status +bit in the PCI Status register in the PCI Configuration Header of +the device to the logical OR of all bits in ISR status field of +the device. Device then asserts/deasserts INT\#x interrupts unless masked +according to standard PCI rules \hyperref[intro:PCI]{[PCI]}. -See sections \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Virtqueue Interrupts From The Device} and \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes} for how this is used. +Device MUST reset the ISR status field to 0 on read. -The \field{offset} for the ISR status has no specific alignment requirements. +In this way, driver read of ISR status causes the device to de-assert +an interrupt. \subsubsection{Device specific structure}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / Device specific structure} |