Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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 000000000..aa39f8d7b
--- /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