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Document backwards-compatibility behaviour

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Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
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Peter Hutterer 2013-10-10 11:22:48 +10:00
parent 306f856f67
commit 346e3eed6a
1 changed files with 56 additions and 0 deletions
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libevdev/libevdev.h
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@ -135,6 +135,12 @@ extern "C" {
* A more complete example is available with the libevdev-events tool here:
* http://cgit.freedesktop.org/libevdev/tree/tools/libevdev-events.c
*
* Backwards compatibility with older kernel
* =========================================
* libevdev attempts to build and run correctly on a number of kernel versions.
* If features required are not available, libevdev attempts to work around them
* in the most reasonable way. For more details see \ref backwardscompatibility.
*
* libevdev internal test suite
* ============================
*
@ -189,6 +195,56 @@ extern "C" {
* https://bugs.freedesktop.org/enter_bug.cgi?product=libevdev
*/
/**
* @page backwardscompatibility Compatibility and Behavior across kernel versions
*
* This page describes libevdev's behavior when the build-time kernel and the
* run-time kernel differ in their feature set.
*
* With the exception of event names, libevdev defines features that may be
* missing on older kernels and building on such kernels will not disable
* features. Running libevdev on a kernel that is missing some feature will
* change libevdev's behavior. In most cases, the new behavior should be
* obvious, but it is spelled out below in detail.
*
* Minimum requirements
* ====================
* libevdev requires a 2.6.36 kernel as minimum. Specifically, it requires
* ABS_MT_SLOT and the matching behavior.
*
* Event and input property names
* ==============================
* Event names and input property names are defined at build-time by the
* linux/input.h shipped with libevedv.
* The list of event names is compiled at build-time and thus any events not defined
* at build time will not resolve. Specifically,
* libevdev_event_code_get_name(type, code) for an undefined type or code will
* always return NULL. Likewise, libevdev_property_get_name() will return NULL
* for properties undefined on the build system.
*
* Input properties
* ================
* If the kernel does not support input properties, specifically the
* EVIOCGPROPS ioclt, libevdev does not expose input properties to the caller.
* Specifically, libevdev_has_property() will always return 0 unless the
* property has been manually set with libevdev_enable_property().
*
* This also applies to the libevdev-uinput code. If uinput does not honor
* UI_SET_PROPBIT, libevdev will continue without setting the properties on
* the device.
*
* MT slot behavior
* =================
* If the kernel does not support the EVIOCGMTSLOTS ioctl, libevdev continues
* as normal and assumes all values in all slots to be 0.
*
* SYN_DROPPED behavior
* ====================
* A kernel without SYN_DROPPED, won't send the event. libevdev_next_event()
* will never require the switch to sync mode.
*
*/
/**
* @defgroup init Initialization and setup
*