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author | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-06-01 13:29:14 +1000 |
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committer | Stephen Rothwell <sfr@canb.auug.org.au> | 2017-06-01 13:29:14 +1000 |
commit | cd76e9346ecb8f33c2b6e73c3f48017e402bfc31 (patch) | |
tree | cf5051564d3d0ffa9b5afbb85354026f6b13bdb9 /Documentation | |
parent | 5f875a325c30056ddbe2bf0b3612f719681fa4ff (diff) | |
parent | e622ec579b9ac3a3280088b991e3a26309582b3b (diff) |
Merge remote-tracking branch 'driver-core/driver-core-next'
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/ABI/testing/sysfs-uevent | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-uevent b/Documentation/ABI/testing/sysfs-uevent new file mode 100644 index 000000000000..aa39f8d7bcdf --- /dev/null +++ b/Documentation/ABI/testing/sysfs-uevent @@ -0,0 +1,47 @@ +What: /sys/.../uevent +Date: May 2017 +KernelVersion: 4.13 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: + Enable passing additional variables for synthetic uevents that + are generated by writing /sys/.../uevent file. + + Recognized extended format is 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" + 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 + variable. + + If UUID is not passed in, the generated synthetic uevent gains + "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 + with existing variables. + + 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: + + ACTION=add + SYNTH_ARG_A=1 + SYNTH_ARG_B=abc + SYNTH_UUID=fe4d7c9d-b8c6-4a70-9ef1-3d8a58d18eed +Users: + udev, userspace tools generating synthetic uevents |