mi: Add initial mi document

Add a base `mi.rst.in` document, for some background information on the
NVMe-MI interface, alongside the new mi API doc.

Signed-off-by: Jeremy Kerr <[email protected]>

Author: jk-ozlabs

doc/index.rst

@@ -12,6 +12,7 @@ and utilities to connect, scan, and manage nvme devices on a Linux system.
 
    installation.rst
    quickstart.rst
+   mi.rst
    api.rst
 
 Indices and tables

doc/index.rst.in

@@ -12,6 +12,7 @@ and utilities to connect, scan, and manage nvme devices on a Linux system.
 
    installation.rst
    quickstart.rst
+   mi.rst
    api.rst
 
 Indices and tables

doc/meson.build

@@ -26,6 +26,7 @@ sphinx_sources = [
     'index.rst',
     'quickstart.rst',
     'installation.rst',
+    'mi.rst',
     'config-schema.json'
 ]
 

doc/mi.rst.in

@@ -0,0 +1,29 @@
+NVMe Management Interface (NVMe-MI) support
+===========================================
+
+This libnvme project also includes support for the NVMe Management Interface
+(NVMe-MI), currently over a Management Component Transport (MCTP)
+protocol link. This MCTP link will typically use i2c/SMBus as the
+hardware transport, enabling out-of-band management and control over NVMe
+devices using a simple SMBus interface.
+
+The MI interface is compiled into a separate shared object, ``libnvme-mi.so``.
+
+Most of the MI API is transport-agnostic, except for the endpoint constructor
+functions. Once an endpoint object (``nvme_mi_ep_t``) is created, the generic
+functions can be used to manage it.
+
+MCTP Transport
+--------------
+
+The MI API is generally transport-agnostic, but the only currently-supported
+transport is MCTP, using the kernel ``AF_MCTP`` socket interface.
+
+MCTP endpoints are addressed by a (network-id, endpoint-id) pair. Endpoint
+IDs (EIDs) are defined by the MCTP standard as an 8-bit value. Since the
+address space is somewhat limited, the Linux `AF_MCTP` support allows for
+separate MCTP "networks", which provide separate address spaces. These networks
+each have a unique ``unsigned int`` as their ID.
+
+The default Network ID is 1; unless you have configured otherwise, MCTP
+endpoints will appear on this network.