Add a man page update describing how daxctl-reconfigure-device(1) can be used for persistent reconfiguration of a daxctl device using a config file.
Cc: Dan Williams <[email protected]> Signed-off-by: Vishal Verma <[email protected]> --- .../daxctl/daxctl-reconfigure-device.txt | 67 +++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/Documentation/daxctl/daxctl-reconfigure-device.txt b/Documentation/daxctl/daxctl-reconfigure-device.txt index f112b3c..1e2d380 100644 --- a/Documentation/daxctl/daxctl-reconfigure-device.txt +++ b/Documentation/daxctl/daxctl-reconfigure-device.txt @@ -162,6 +162,15 @@ include::region-option.txt[] brought online automatically and immediately with the 'online_movable' policy. Use this option to disable the automatic onlining behavior. +-C:: +--check-config:: + Get reconfiguration parameters from the global daxctl config file. + This is typically used when daxctl-reconfigure-device is called from + a systemd-udevd device unit file. The reconfiguration proceeds only + if the UUID of the dax device passed in on the command line matches + a UUID listed in the auto-online section of the config. See the + 'PERSISTENT RECONFIGURATION' section for more details. + include::movable-options.txt[] -f:: @@ -183,6 +192,64 @@ include::human-option.txt[] include::verbose-option.txt[] +PERSISTENT RECONFIGURATION +-------------------------- + +The 'mode' of a daxctl device is not persistent across reboots by default. This +is because the device itself may hold any metadata that hints at what mode it +was set to, or is intended to be used in. The default mode for such a device +is 'devdax', and on reboot, that is the mode devices appear in by default. + +The administrator may desire to configure the system in a way that certain +dax devices are always reconfigured into a certain mode every time on boot. +This is accomplished via a daxctl config file located at [location TBD]. + +The config file may have multiple sections influencing different aspects of +daxctl operation. The section of interest for persistent reconfiguration is +'auto-online'. The format of this is as follows: + +---- +[auto-online <subsection_name>] +uuid = <namespace uuid> +mode = <desired reconfiguration mode> (default: system-ram) +online = <true|false> (default: true) +movable = <true|false> (default: true) +---- + +Here is an example of a config snippet for managing three devdax namespaces, +one is left in devdax mode, the second is changed to system-ram mode with +default options (online, movable), and the third is set to system-ram mode, +the memory is onlined, but not movable. + +Note that the 'subsection name' can be arbitrary, and is only used to +identify a specific config section. It does not have to match the 'device +name' (e.g. 'dax0.0' etc). + +---- +[auto-online dax0] +uuid = ed93e918-e165-49d8-921d-383d7b9660c5 +mode = devdax + +[auto-online dax1] +uuid = f36d02ff-1d9f-4fb9-a5b9-8ceb10a00fe3 +mode = system-ram + +[auto-online dax2] +uuid = f36d02ff-1d9f-4fb9-a5b9-8ceb10a00fe3 +mode = system-ram +online = true +movable = false +---- + +The following example can be used to create a devdax mode namespace, and +simultaneously add the newly created namespace to the config file for +system-ram conversion. + +---- +ndctl create-namespace --mode=devdax | \ + jq -r "\"[auto-online $(uuidgen)]\", \"uuid = \(.uuid)\", \"mode = system-ram\"" >> $config_path +---- + include::../copyright.txt[] SEE ALSO -- 2.31.1
