linux/Documentation/ABI
Linus Torvalds b5e16170f5 MTD updates for v4.13-rc1:
General updates
 
  * Cleanups and additional flash support for "dataflash" driver
  * new driver for mchp23k256 SPI SRAM device
  * improve handling of MTDs without eraseblocks (i.e., MTD_NO_ERASE)
  * refactor and improve "sub-partition" handling with TRX partition
    parser; partitions can now be created as sub-partitions of another
    partition
 
 SPI NOR updates, from Cyrille Pitchen and Marek Vasut:
  * introduce support to the SPI 1-2-2 and 1-4-4 protocols.
  * introduce support to the Double Data Rate (DDR) mode.
  * introduce support to the Octo SPI protocols.
  * add support to new memory parts for Spansion, Macronix and Winbond.
  * add fixes for the Aspeed, STM32 and Cadence QSPI controler drivers.
  * clean up the st_spi_fsm driver.
 
 NAND updates, from Boris Brezillon:
 
  * addition of on-die ECC support to Micron driver
  * addition of helpers to help drivers choose most appropriate ECC
    settings
  * deletion of dead-code (cached programming and ->errstat() hook)
  * make sure drivers that do not support the SET/GET FEATURES command
    return ENOTSUPP use a dummy ->set/get_features implementation
    returning -ENOTSUPP (required for Micron on-die ECC)
  * change the semantic of ecc->write_page() for drivers setting the
    NAND_ECC_CUSTOM_PAGE_ACCESS flag
  * support exiting 'GET STATUS' command in default ->cmdfunc()
    implementations
  * change the prototype of ->setup_data_interface()
 
  A bunch of driver related changes:
 
  * various cleanup, fixes and improvements of the MTK driver
  * OMAP DT bindings fixes
  * support for ->setup_data_interface() in the fsmc driver
  * support for imx7 in the gpmi driver
  * finalization of the denali driver rework (thanks to Masahiro for the
    work he's done on this driver)
  * fix "bitflips in erased pages" handling in the ifc driver
  * addition of PM ops and dynamic timing configuration to the atmel
    driver
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Merge tag 'for-linus-20170713' of git://git.infradead.org/linux-mtd

Pull MTD updates from Brian Norris:
 "General updates:
   - Cleanups and additional flash support for "dataflash" driver
   - new driver for mchp23k256 SPI SRAM device
   - improve handling of MTDs without eraseblocks (i.e., MTD_NO_ERASE)
   - refactor and improve "sub-partition" handling with TRX partition
     parser; partitions can now be created as sub-partitions of another
     partition

  SPINOR updates, from Cyrille Pitchen and Marek Vasut:
   - introduce support to the SPI 1-2-2 and 1-4-4 protocols.
   - introduce support to the Double Data Rate (DDR) mode.
   - introduce support to the Octo SPI protocols.
   - add support to new memory parts for Spansion, Macronix and Winbond.
   - add fixes for the Aspeed, STM32 and Cadence QSPI controler drivers.
   - clean up the st_spi_fsm driver.

  NAND updates, from Boris Brezillon:
   - addition of on-die ECC support to Micron driver
   - addition of helpers to help drivers choose most appropriate ECC
     settings
   - deletion of dead-code (cached programming and ->errstat() hook)
   - make sure drivers that do not support the SET/GET FEATURES command
     return ENOTSUPP use a dummy ->set/get_features implementation
     returning -ENOTSUPP (required for Micron on-die ECC)
   - change the semantic of ecc->write_page() for drivers setting the
     NAND_ECC_CUSTOM_PAGE_ACCESS flag
   - support exiting 'GET STATUS' command in default ->cmdfunc()
     implementations
   - change the prototype of ->setup_data_interface()

  A bunch of driver related changes:
   - various cleanup, fixes and improvements of the MTK driver
   - OMAP DT bindings fixes
   - support for ->setup_data_interface() in the fsmc driver
   - support for imx7 in the gpmi driver
   - finalization of the denali driver rework (thanks to Masahiro for
     the work he's done on this driver)
   - fix "bitflips in erased pages" handling in the ifc driver
   - addition of PM ops and dynamic timing configuration to the atmel
     driver"

* tag 'for-linus-20170713' of git://git.infradead.org/linux-mtd: (118 commits)
  Documentation: ABI: mtd: describe "offset" more precisely
  mtd: Fix check in mtd_unpoint()
  mtd: nand: mtk: release lock on error path
  mtd: st_spi_fsm: remove SPINOR_OP_RDSR2 and use SPINOR_OP_RDCR instead
  mtd: spi-nor: cqspi: remove duplicate const
  mtd: spi-nor: Add support for Spansion S25FL064L
  mtd: spi-nor: Add support for mx66u51235f
  mtd: nand: mtk: add ->setup_data_interface() hook
  mtd: nand: mtk: remove unneeded mtk_ecc_hw_init from mtk_ecc_resume
  mtd: nand: mtk: remove unneeded mtk_nfc_hw_init from mtk_nfc_resume
  mtd: nand: mtk: disable ecc irq when writing page with hwecc
  mtd: nand: mtk: fix incorrect register setting order about ecc irq
  mtd: partitions: fixup some allocate_partition() whitespace
  mtd: parsers: trx: fix pr_err format for printing offset
  MAINTAINERS: Update SPI NOR subsystem git repositories
  mtd: extract TRX parser out of bcm47xxpart into a separated module
  mtd: partitions: add support for partition parsers
  mtd: partitions: add support for subpartitions
  mtd: partitions: rename "master" to the "parent" where appropriate
  mtd: partitions: remove sysfs files when deleting all master's partitions
  ...
2017-07-13 12:07:44 -07:00
..
obsolete ACPI / scan: Drop support for force_remove 2017-04-13 03:51:47 +02:00
removed
stable xen: features and fixes for 4.13-rc1 2017-07-06 19:11:24 -07:00
testing MTD updates for v4.13-rc1: 2017-07-13 12:07:44 -07:00
README docs: fix locations of several documents that got moved 2016-10-24 08:12:35 -02:00

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/process/stable-api-nonsense.rst.