linux/Documentation/ABI
Linus Torvalds ef9a61bef9 - factor out common code from MTD tests
- nand-gpio cleanup and portability to non-ARM
  - m25p80 support for 4-byte addressing chips, other new chips
  - pxa3xx cleanup and support for new platforms
  - remove obsolete alauda, octagon-5066 drivers
  - erase/write support for bcm47xxsflash
  - improve detection of ECC requirements for NAND, controller setup
  - NFC acceleration support for atmel-nand, read/write via SRAM
  - etc.
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Merge tag 'for-linus-20130909' of git://git.infradead.org/linux-mtd

Pull mtd updates from David Woodhouse:
 - factor out common code from MTD tests
 - nand-gpio cleanup and portability to non-ARM
 - m25p80 support for 4-byte addressing chips, other new chips
 - pxa3xx cleanup and support for new platforms
 - remove obsolete alauda, octagon-5066 drivers
 - erase/write support for bcm47xxsflash
 - improve detection of ECC requirements for NAND, controller setup
 - NFC acceleration support for atmel-nand, read/write via SRAM
 - etc

* tag 'for-linus-20130909' of git://git.infradead.org/linux-mtd: (184 commits)
  mtd: chips: Add support for PMC SPI Flash chips in m25p80.c
  mtd: ofpart: use for_each_child_of_node() macro
  mtd: mtdswap: replace strict_strtoul() with kstrtoul()
  mtd cs553x_nand: use kzalloc() instead of memset
  mtd: atmel_nand: fix error return code in atmel_nand_probe()
  mtd: bcm47xxsflash: writing support
  mtd: bcm47xxsflash: implement erasing support
  mtd: bcm47xxsflash: convert to module_platform_driver instead of init/exit
  mtd: bcm47xxsflash: convert kzalloc to avoid invalid access
  mtd: remove alauda driver
  mtd: nand: mxc_nand: mark 'const' properly
  mtd: maps: cfi_flagadm: add missing __iomem annotation
  mtd: spear_smi: add missing __iomem annotation
  mtd: r852: Staticize local symbols
  mtd: nandsim: Staticize local symbols
  mtd: impa7: add missing __iomem annotation
  mtd: sm_ftl: Staticize local symbols
  mtd: m25p80: add support for mr25h10
  mtd: m25p80: make CONFIG_M25PXX_USE_FAST_READ safe to enable
  mtd: m25p80: Pass flags through CAT25_INFO macro
  ...
2013-09-09 10:33:19 -07:00
..
obsolete Merge branches 'for-3.7/upstream-fixes', 'for-3.8/hidraw', 'for-3.8/i2c-hid', 'for-3.8/multitouch', 'for-3.8/roccat', 'for-3.8/sensors' and 'for-3.8/upstream' into for-linus 2012-12-12 21:41:55 +01:00
removed
stable Documentation sysfs-bus-usb: Document which files are used by libusb 2013-08-30 11:13:26 -07:00
testing - factor out common code from MTD tests 2013-09-09 10:33:19 -07:00
README Documentation: remove reference to feature-removal-schedule.txt 2012-12-17 17:15:12 -08:00

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.