[PATCH v6 1/5] Introduce device group

[Max Gurtovoy <mgurtovoy@nvidia.com>]

Each device group has a type. For now, define 2 initial types of device
groups: Self type and SR-IOV type.

Self type - A group that has a single virtio device as a member.

SR-IOV type - A virtio PCI SR-IOV physical function (PF) and its
PCI SR-IOV virtual functions (VFs). This group may contain one or more
virtio devices.

Each device group has a unique identifier. This identifier is the group
identifier (group_id).

Each device within a device group has a unique identifier. This identifier
is the group member identifier (group_member_id).

Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
---
 introduction.tex | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/introduction.tex b/introduction.tex
index aa9ec1b..e8bde45 100644
--- a/introduction.tex
+++ b/introduction.tex
@@ -156,6 +156,30 @@ \subsection{Transition from earlier specification drafts}\label{sec:Transition f
 sections tagged "Legacy Interface" in the section title.
 These highlight the changes made since the earlier drafts.
 
+\subsection{Device group}\label{sec:Introduction / Terminology / Device group}
+
+A device group includes one or more virtio devices. Each device group has a unique group identifier (group_id).
+A device can be a member of one or more device groups.
+A device within a group is identified by a unique group member identifier (group_member_id).
+The scope of the group member identifier is within the group. In other words, two device groups can have overlap group member identifiers.
+A group member identifier is a 64-bit value in range of 0x0 - 0xFFFFFFFFFFFFFFF0.
+A special group member identifier value of 0xFFFFFFFFFFFFFFFF refers to all the devices in a device group.
+
+The supported device groups are:
+\begin{enumerate}
+\item Self type (group identifier = 0) - this group has only one device in the group. Each virtio device is a member of at least one device group, the Self type group.
+For this group type, the device is identified by group member identifier of 0.
+
+\item SR-IOV type (group identifier = 1) - this group includes a virtio PCI SR-IOV physical function (PF) and all its virtual functions (VFs).
+For this group type, the PF device has group member identifier of 0. Each VF group member identifier equals the PCI VF number according to the PCI Express Base Specification
+(Single Root I/O Virtualization and Sharing chapter). Devices that are members in this group use the Virtio PCI transport (for more details see \ref{sec:Virtio Transport Options / Virtio Over PCI Bus}).
+\end{enumerate}
+
+\begin{note}
+  The same device can be identified by different identifiers within different groups. For example, A virtual function device has a group
+  member identifier equals to 0 within Self type group and a group member identifier equals to VF number (e.g 4) within SR-IOV type group.
+\end{note}
+
 \section{Structure Specifications}\label{sec:Structure Specifications}
 
 Many device and driver in-memory structure layouts are documented using
-- 
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