linux/Documentation/ABI
Linus Torvalds 9dffdb38d8 Staging driver patches for 4.6-rc1
Here is the big staging driver pull request for 4.6-rc1.
 
 Lots of little things here, over 1600 patches or so.  Notible is all of
 the good Lustre work happening, those developers have finally woken up
 and are cleaning up their code greatly.  The Outreachy intern
 application process is also happening, which brought in another 400 or
 so patches.  Full details are in the very long shortlog.
 
 All of these have been in linux-next with no reported issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'staging-4.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging

Pull staging driver updates from Greg KH:
 "Here is the big staging driver pull request for 4.6-rc1.

  Lots of little things here, over 1600 patches or so.  Notable is all
  of the good Lustre work happening, those developers have finally woken
  up and are cleaning up their code greatly.  The Outreachy intern
  application process is also happening, which brought in another 400 or
  so patches.  Full details are in the very long shortlog.

  All of these have been in linux-next with no reported issues"

* tag 'staging-4.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (1673 commits)
  staging: lustre: fix aligments in lnet selftest
  staging: lustre: report minimum of two buffers for LNet selftest load test
  staging: lustre: test for proper errno code in lstcon_rpc_trans_abort
  staging: lustre: filter remaining extra spacing for lnet selftest
  staging: lustre: remove extra spacing when setting variable for lnet selftest
  staging: lustre: remove extra spacing of variable declartions for lnet selftest
  staging: lustre: fix spacing issues checkpatch reported in lnet selftest
  staging: lustre: remove returns in void function for lnet selftest
  staging: lustre: fix bogus lst errors for lnet selftest
  staging: netlogic: Replacing pr_err with dev_err after the call to devm_kzalloc
  staging: mt29f_spinand: Replacing pr_info with dev_info after the call to devm_kzalloc
  staging: android: ion: fix up file mode
  staging: ion: debugfs invalid gfp mask
  staging: rts5208: Replace pci_enable_device with pcim_enable_device
  Staging: ieee80211: Place constant on right side of the test.
  staging: speakup: Replace del_timer with del_timer_sync
  staging: lowmemorykiller: fix 2 checks that checkpatch complained
  staging: mt29f_spinand: Drop void pointer cast
  staging: rdma: hfi1: file_ops: Replace ALIGN with PAGE_ALIGN
  staging: rdma: hfi1: driver: Replace IS_ALIGNED with PAGE_ALIGNED
  ...
2016-03-17 22:13:41 -07:00
..
obsolete gpio: ABI: mark the sysfs ABI as obsolete 2016-02-09 11:09:55 +01:00
removed net_dma: simple removal 2014-09-28 07:05:16 -07:00
stable Drivers: hv: vmbus: Add vendor and device atttributes 2016-02-07 21:32:57 -08:00
testing Staging driver patches for 4.6-rc1 2016-03-17 22:13:41 -07:00
README Documentation/ABI: document the non-ABI status of Kconfig and symbols 2013-11-13 12:09:32 +09:00

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.