linux/Documentation/ABI
Linus Torvalds 05fde26a94 platform-drivers-x86 got 4.2
asus-wmi: Fan control
 dell*: Add Dell airplane mode switch driver
 ideapad-laptop: Platform rfkill fixes, and regression fix
 pvpanic: Handle missing _STA correctly
 toshiba*: Rafactor bluetooth support, haps documentation, driver cleanup
 other: Use acpi_video_unregister_backlight instead of acpi_video_unregister in
        serveral drivers.
        Orphan msi-wmi.
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Merge tag 'platform-drivers-x86-v4.2-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86

Pull x86 platform driver updates from Darren Hart:
 "Fairly routine update for platform-drivers-x86.

  Mostly fixes and cleanups, with a significant refactoring of toshiba*
  drivers.  Includes the addition of the dell-rbtn driver.

  Details:

  asus-wmi:
   - fan control

  dell*:
   - add Dell airplane mode switch driver

  ideapad-laptop:
   - platform rfkill fixes, and regression fix

  pvpanic:
   - handle missing _STA correctly

  toshiba*:
   - rafactor bluetooth support
   - haps documentation
   - driver cleanup

  other:
   - Use acpi_video_unregister_backlight instead of
     acpi_video_unregister in serveral drivers.
   - Orphan msi-wmi.

* tag 'platform-drivers-x86-v4.2-1' of git://git.infradead.org/users/dvhart/linux-platform-drivers-x86: (24 commits)
  MAINTAINERS: Orphan x86 driver msi-wmi
  ideapad: fix software rfkill setting
  dell-laptop: Use dell-rbtn instead i8042 filter when possible
  dell-rbtn: Export notifier for other kernel modules
  dell-rbtn: Dell Airplane Mode Switch driver
  samsung-laptop: Use acpi_video_unregister_backlight instead of acpi_video_unregister
  asus-wmi: Use acpi_video_unregister_backlight instead of acpi_video_unregister
  apple_gmux: Use acpi_video_unregister_backlight instead of acpi_video_unregister
  pvpanic: handle missing _STA correctly
  ideapad_laptop: Lenovo G50-30 fix rfkill reports wireless blocked
  asus-wmi: add fan control
  Documentation/ABI: Add file describing the sysfs entries for toshiba_haps
  toshiba_haps: Make use of DEVICE_ATTR_{RW, WO} macros
  toshiba_haps: Replace sscanf with kstrtoint
  toshiba_acpi: Bump driver version to 0.22
  toshiba_acpi: Remove TOS_FAILURE check from some functions
  toshiba_acpi: Comments cleanup
  toshiba_acpi: Rename hci_{read, write}1 functions
  toshiba_acpi: Remove no longer needed hci_{read, write}2 functions
  toshiba_bluetooth: Change BT status message to debug
  ...
2015-07-01 18:55:34 -07:00
..
obsolete zram: deprecate zram attrs sysfs nodes 2015-04-15 16:35:21 -07:00
removed net_dma: simple removal 2014-09-28 07:05:16 -07:00
stable w1: Add support for DS28EA00 sequence to w1-therm 2015-05-24 12:08:59 -07:00
testing platform-drivers-x86 got 4.2 2015-07-01 18:55:34 -07:00
README Documentation/ABI: document the non-ABI status of Kconfig and symbols 2013-11-13 12:09:32 +09:00

README

This directory attempts to document the ABI between the Linux kernel and
userspace, and the relative stability of these interfaces.  Due to the
everchanging nature of Linux, and the differing maturity levels, these
interfaces should be used by userspace programs in different ways.

We have four different levels of ABI stability, as shown by the four
different subdirectories in this location.  Interfaces may change levels
of stability according to the rules described below.

The different levels of stability are:

  stable/
	This directory documents the interfaces that the developer has
	defined to be stable.  Userspace programs are free to use these
	interfaces with no restrictions, and backward compatibility for
	them will be guaranteed for at least 2 years.  Most interfaces
	(like syscalls) are expected to never change and always be
	available.

  testing/
	This directory documents interfaces that are felt to be stable,
	as the main development of this interface has been completed.
	The interface can be changed to add new features, but the
	current interface will not break by doing this, unless grave
	errors or security problems are found in them.  Userspace
	programs can start to rely on these interfaces, but they must be
	aware of changes that can occur before these interfaces move to
	be marked stable.  Programs that use these interfaces are
	strongly encouraged to add their name to the description of
	these interfaces, so that the kernel developers can easily
	notify them if any changes occur (see the description of the
	layout of the files below for details on how to do this.)

  obsolete/
  	This directory documents interfaces that are still remaining in
	the kernel, but are marked to be removed at some later point in
	time.  The description of the interface will document the reason
	why it is obsolete and when it can be expected to be removed.

  removed/
	This directory contains a list of the old interfaces that have
	been removed from the kernel.

Every file in these directories will contain the following information:

What:		Short description of the interface
Date:		Date created
KernelVersion:	Kernel version this feature first showed up in.
Contact:	Primary contact for this interface (may be a mailing list)
Description:	Long description of the interface and how to use it.
Users:		All users of this interface who wish to be notified when
		it changes.  This is very important for interfaces in
		the "testing" stage, so that kernel developers can work
		with userspace developers to ensure that things do not
		break in ways that are unacceptable.  It is also
		important to get feedback for these interfaces to make
		sure they are working in a proper way and do not need to
		be changed further.


How things move between levels:

Interfaces in stable may move to obsolete, as long as the proper
notification is given.

Interfaces may be removed from obsolete and the kernel as long as the
documented amount of time has gone by.

Interfaces in the testing state can move to the stable state when the
developers feel they are finished.  They cannot be removed from the
kernel tree without going through the obsolete state first.

It's up to the developer to place their interfaces in the category they
wish for it to start out in.


Notable bits of non-ABI, which should not under any circumstances be considered
stable:

- Kconfig.  Userspace should not rely on the presence or absence of any
  particular Kconfig symbol, in /proc/config.gz, in the copy of .config
  commonly installed to /boot, or in any invocation of the kernel build
  process.

- Kernel-internal symbols.  Do not rely on the presence, absence, location, or
  type of any kernel symbol, either in System.map files or the kernel binary
  itself.  See Documentation/stable_api_nonsense.txt.