1.. SPDX-License-Identifier: GPL-2.0
2
3==============
4Devlink Region
5==============
6
7``devlink`` regions enable access to driver defined address regions using
8devlink.
9
10Each device can create and register its own supported address regions. The
11region can then be accessed via the devlink region interface.
12
13Region snapshots are collected by the driver, and can be accessed via read
14or dump commands. This allows future analysis on the created snapshots.
15Regions may optionally support triggering snapshots on demand.
16
17The major benefit to creating a region is to provide access to internal
18address regions that are otherwise inaccessible to the user.
19
20Regions may also be used to provide an additional way to debug complex error
21states, but see also :doc:`devlink-health`
22
23Regions may optionally support capturing a snapshot on demand via the
24``DEVLINK_CMD_REGION_NEW`` netlink message. A driver wishing to allow
25requested snapshots must implement the ``.snapshot`` callback for the region
26in its ``devlink_region_ops`` structure.
27
28example usage
29-------------
30
31.. code:: shell
32
33    $ devlink region help
34    $ devlink region show [ DEV/REGION ]
35    $ devlink region del DEV/REGION snapshot SNAPSHOT_ID
36    $ devlink region dump DEV/REGION [ snapshot SNAPSHOT_ID ]
37    $ devlink region read DEV/REGION [ snapshot SNAPSHOT_ID ] address ADDRESS length length
38
39    # Show all of the exposed regions with region sizes:
40    $ devlink region show
41    pci/0000:00:05.0/cr-space: size 1048576 snapshot [1 2]
42    pci/0000:00:05.0/fw-health: size 64 snapshot [1 2]
43
44    # Delete a snapshot using:
45    $ devlink region del pci/0000:00:05.0/cr-space snapshot 1
46
47    # Request an immediate snapshot, if supported by the region
48    $ devlink region new pci/0000:00:05.0/cr-space snapshot 5
49
50    # Dump a snapshot:
51    $ devlink region dump pci/0000:00:05.0/fw-health snapshot 1
52    0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30
53    0000000000000010 0000 0000 ffff ff04 0029 8c00 0028 8cc8
54    0000000000000020 0016 0bb8 0016 1720 0000 0000 c00f 3ffc
55    0000000000000030 bada cce5 bada cce5 bada cce5 bada cce5
56
57    # Read a specific part of a snapshot:
58    $ devlink region read pci/0000:00:05.0/fw-health snapshot 1 address 0 length 16
59    0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30
60
61As regions are likely very device or driver specific, no generic regions are
62defined. See the driver-specific documentation files for information on the
63specific regions a driver supports.
64