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authorDaniel Vetter <daniel.vetter@ffwll.ch>2017-07-26 13:23:10 +0200
committerDaniel Vetter <daniel.vetter@ffwll.ch>2017-07-26 13:43:33 +0200
commitaf055598542670c8533a58582813b1419949cae0 (patch)
tree901fa1bf635d5c1e91d08f9f4c2e4943516dbb71 /Documentation/ABI/testing/sysfs-uevent
parentdrm/syncobj: Fix kerneldoc (diff)
parentMerge tag 'drm-intel-next-2017-07-17' of git://anongit.freedesktop.org/git/drm-intel into drm-next (diff)
downloadlinux-dev-af055598542670c8533a58582813b1419949cae0.tar.xz
linux-dev-af055598542670c8533a58582813b1419949cae0.zip
Merge airlied/drm-next into drm-misc-next
I need this to be able to apply the deferred fbdev setup patches, I need the relevant prep work that landed through the drm-intel tree. Also squash in conflict fixup from Laurent Pinchart. Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
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+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