71 lines
2.8 KiB
ReStructuredText
71 lines
2.8 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0
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==============
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Devlink Region
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==============
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``devlink`` regions enable access to driver defined address regions using
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devlink.
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Each device can create and register its own supported address regions. The
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region can then be accessed via the devlink region interface.
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Region snapshots are collected by the driver, and can be accessed via read
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or dump commands. This allows future analysis on the created snapshots.
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Regions may optionally support triggering snapshots on demand.
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Snapshot identifiers are scoped to the devlink instance, not a region.
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All snapshots with the same snapshot id within a devlink instance
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correspond to the same event.
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The major benefit to creating a region is to provide access to internal
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address regions that are otherwise inaccessible to the user.
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Regions may also be used to provide an additional way to debug complex error
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states, but see also Documentation/networking/devlink/devlink-health.rst
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Regions may optionally support capturing a snapshot on demand via the
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``DEVLINK_CMD_REGION_NEW`` netlink message. A driver wishing to allow
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requested snapshots must implement the ``.snapshot`` callback for the region
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in its ``devlink_region_ops`` structure. If snapshot id is not set in
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the ``DEVLINK_CMD_REGION_NEW`` request kernel will allocate one and send
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the snapshot information to user space.
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example usage
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-------------
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.. code:: shell
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$ devlink region help
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$ devlink region show [ DEV/REGION ]
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$ devlink region del DEV/REGION snapshot SNAPSHOT_ID
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$ devlink region dump DEV/REGION [ snapshot SNAPSHOT_ID ]
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$ devlink region read DEV/REGION [ snapshot SNAPSHOT_ID ] address ADDRESS length length
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# Show all of the exposed regions with region sizes:
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$ devlink region show
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pci/0000:00:05.0/cr-space: size 1048576 snapshot [1 2] max 8
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pci/0000:00:05.0/fw-health: size 64 snapshot [1 2] max 8
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# Delete a snapshot using:
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$ devlink region del pci/0000:00:05.0/cr-space snapshot 1
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# Request an immediate snapshot, if supported by the region
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$ devlink region new pci/0000:00:05.0/cr-space
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pci/0000:00:05.0/cr-space: snapshot 5
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# Dump a snapshot:
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$ devlink region dump pci/0000:00:05.0/fw-health snapshot 1
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0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30
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0000000000000010 0000 0000 ffff ff04 0029 8c00 0028 8cc8
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0000000000000020 0016 0bb8 0016 1720 0000 0000 c00f 3ffc
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0000000000000030 bada cce5 bada cce5 bada cce5 bada cce5
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# Read a specific part of a snapshot:
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$ devlink region read pci/0000:00:05.0/fw-health snapshot 1 address 0 length 16
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0000000000000000 0014 95dc 0014 9514 0035 1670 0034 db30
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As regions are likely very device or driver specific, no generic regions are
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defined. See the driver-specific documentation files for information on the
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specific regions a driver supports.
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