Add VIRTIO_PCI_CAP_GROUP_ID_CFG (Group Identifier) capability to the
virtio PCI capabilities to allow for the grouping of devices.
Signed-off-by: Venu Busireddy <venu.busire...@oracle.com>
---
content.tex | 43 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/content.tex b/content.tex
index 7a92cb1..7ea6267 100644
--- a/content.tex
+++ b/content.tex
@@ -599,6 +599,8 @@ The fields are interpreted as follows:
#define VIRTIO_PCI_CAP_DEVICE_CFG 4
/* PCI configuration access */
#define VIRTIO_PCI_CAP_PCI_CFG 5
+/* Group Identifier */
+#define VIRTIO_PCI_CAP_GROUP_ID_CFG 6
\end{lstlisting}
Any other value is reserved for future use.
@@ -997,6 +999,47 @@ address \field{cap.length} bytes within a BAR range
specified by some other Virtio Structure PCI Capability
of type other than \field{VIRTIO_PCI_CAP_PCI_CFG}.
+\subsubsection{Group Identifier capability}\label{sec:Virtio Transport Options
/ Virtio Over PCI Bus / PCI Device Layout / Group Identifier capability}
+
+The VIRTIO_PCI_CAP_GROUP_ID_CFG capability provides means for grouping devices
together.
+
+The capability is immediately followed by an identifier of arbitrary size as
below:
+
+\begin{lstlisting}
+struct virtio_pci_group_id_cap {
+ struct virtio_pci_cap cap;
+ u8 group_id[]; /* Group Identifier */
+};
+\end{lstlisting}
+
+The fields \field{cap.bar}, \field{cap.length}, \field{cap.offset}
+and \field{group_id} are read-only for the driver.
+
+The specification does not impose any restrictions on the size or
+structure of group_id[]. Vendors are free to declare this array as
+large as needed, as long as the combined size of all capabilities can
+be accommodated within the PCI configuration space.
+
+If there is enough room in the PCI configuration space to accommodate
+the group identifier, the fields \field{cap.bar}, \field{cap.offset}
+and \field{cap.length} should be set to 0.
+
+If there isn't enough room, some or all of the group identifier can be
+presented in the BAR region, in which case the fields \field{cap.bar},
+\field{cap.offset} and \field{cap.length} should be set appropriately.
+
+In either case, the field \field{cap.cap_len} indicates the length of
+the group identifier information present in the configuration space
+itself.
+
+\devicenormative{\paragraph}{Group Identifier capability}{Virtio Transport
Options / Virtio Over PCI Bus / PCI Device Layout / Group Identifier capability}
+
+The device MAY present the VIRTIO_PCI_CAP_GROUP_ID_CFG capability.
+
+\drivernormative{\paragraph}{Group Identifier capability}{Virtio Transport
Options / Virtio Over PCI Bus / PCI Device Layout / Group Identifier capability}
+
+The driver MUST NOT write to group_id[] area or the BAR region.
+
\subsubsection{Legacy Interfaces: A Note on PCI Device
Layout}\label{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI Device
Layout / Legacy Interfaces: A Note on PCI Device Layout}
Transitional devices MUST present part of configuration
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