Signed-off-by: Nikos Dragazis <[email protected]>
---
content.tex | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/content.tex b/content.tex
index 628265e..d6fc17e 100644
--- a/content.tex
+++ b/content.tex
@@ -1884,6 +1884,18 @@ \subsection{MMIO Device Register
Layout}\label{sec:Virtio Transport Options / Vi
\field{SHMSel} is unused) results in a base address of
0xffffffffffffffff.
}
+ \hline
+ \mmioreg{Doorbell}{Doorbell Notifier}{0xc0}{W}{
+ Writing a value to this register
+ \ref{sec:Basic Facilities of a Virtio device / Doorbells} triggers a
+ notification to the device. The value written to this register is
+ interpreted as a doorbell index and the corresponding notification
+ concerns this specific doorbell. The mapping of doorbells to
+ doorbell indices is device-specific. One possible mapping would be
+ to use the integers 0 to N-1 as the doorbell indices for a total of
+ N doorbells. The total number of doorbells exposed by the device is
+ also device-specific.
+ }
\hline
\mmioreg{ConfigGeneration}{Configuration atomicity value}{0x0fc}{R}{
Reading from this register returns a value describing a version of the
device-specific configuration space (see \field{Config}).
@@ -1920,6 +1932,9 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio
Transport Options / Vi
The device MUST NOT access virtual queue contents when \field{QueueReady} is
zero (0x0).
+The device MUST ignore doorbell notifications for invalid doorbell
+indices.
+
\drivernormative{\subsubsection}{MMIO Device Register Layout}{Virtio Transport
Options / Virtio Over MMIO / MMIO Device Register Layout}
The driver MUST NOT access memory locations not described in the
table \ref{tab:Virtio Trasport Options / Virtio Over MMIO / MMIO Device
Register Layout}
@@ -1977,6 +1992,8 @@ \subsubsection{Device Initialization}\label{sec:Virtio
Transport Options / Virti
Drivers not expecting shared memory MUST NOT use the shared
memory registers.
+Drivers not expecting doorbells MUST NOT use the doorbell register.
+
Further initialization MUST follow the procedure described in
\ref{sec:General Initialization And Device Operation / Device
Initialization}~\nameref{sec:General Initialization And Device Operation /
Device Initialization}.
--
2.17.1
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