diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-uevent | 28 |
1 files changed, 16 insertions, 12 deletions
diff --git a/Documentation/ABI/testing/sysfs-uevent b/Documentation/ABI/testing/sysfs-uevent index aa39f8d7bcdf..0b6227706b35 100644 --- a/Documentation/ABI/testing/sysfs-uevent +++ b/Documentation/ABI/testing/sysfs-uevent @@ -6,42 +6,46 @@ Description: Enable passing additional variables for synthetic uevents that are generated by writing /sys/.../uevent file. - Recognized extended format is ACTION [UUID [KEY=VALUE ...]. + Recognized extended format is:: - The ACTION is compulsory - it is the name of the uevent action - ("add", "change", "remove"). There is no change compared to - previous functionality here. The rest of the extended format - is optional. + ACTION [UUID [KEY=VALUE ...] + + The ACTION is compulsory - it is the name of the uevent + action (``add``, ``change``, ``remove``). There is no change + compared to previous functionality here. The rest of the + extended format is optional. You need to pass UUID first before any KEY=VALUE pairs. - The UUID must be in "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" + The UUID must be in ``xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`` format where 'x' is a hex digit. The UUID is considered to be a transaction identifier so it's possible to use the same UUID value for one or more synthetic uevents in which case we logically group these uevents together for any userspace listeners. The UUID value appears in uevent as - "SYNTH_UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" environment + ``SYNTH_UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`` environment variable. If UUID is not passed in, the generated synthetic uevent gains - "SYNTH_UUID=0" environment variable automatically. + ``SYNTH_UUID=0`` environment variable automatically. The KEY=VALUE pairs can contain alphanumeric characters only. + It's possible to define zero or more pairs - each pair is then delimited by a space character ' '. Each pair appears in - synthetic uevent as "SYNTH_ARG_KEY=VALUE". That means the KEY - name gains "SYNTH_ARG_" prefix to avoid possible collisions + synthetic uevent as ``SYNTH_ARG_KEY=VALUE``. That means the KEY + name gains ``SYNTH_ARG_`` prefix to avoid possible collisions with existing variables. - Example of valid sequence written to the uevent file: + Example of valid sequence written to the uevent file:: add fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed A=1 B=abc - This generates synthetic uevent including these variables: + This generates synthetic uevent including these variables:: ACTION=add SYNTH_ARG_A=1 SYNTH_ARG_B=abc SYNTH_UUID=fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed + Users: udev, userspace tools generating synthetic uevents |