linux/Documentation/ABI
Linus Torvalds bb41fe35dc Char/Misc and other driver subsystem updates for 6.9-rc1
Here is the big set of char/misc and a number of other driver subsystem
 updates for 6.9-rc1.  Included in here are:
   - IIO driver updates, loads of new ones and evolution of existing ones
   - coresight driver updates
   - const cleanups for many driver subsystems
   - speakup driver additions
   - platform remove callback void cleanups
   - mei driver updates
   - mhi driver updates
   - cdx driver updates for MSI interrupt handling
   - nvmem driver updates
   - other smaller driver updates and cleanups, full details in the
     shortlog
 
 All of these have been in linux-next for a long time with no reported
 issue, other than a build warning with some older versions of gcc for a
 speakup driver, fix for that will come in a few days when I catch up
 with my pending patch queues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc and other driver subsystem updates from Greg KH:
 "Here is the big set of char/misc and a number of other driver
  subsystem updates for 6.9-rc1. Included in here are:

   - IIO driver updates, loads of new ones and evolution of existing ones

   - coresight driver updates

   - const cleanups for many driver subsystems

   - speakup driver additions

   - platform remove callback void cleanups

   - mei driver updates

   - mhi driver updates

   - cdx driver updates for MSI interrupt handling

   - nvmem driver updates

   - other smaller driver updates and cleanups, full details in the
    shortlog

  All of these have been in linux-next for a long time with no reported
  issue, other than a build warning for the speakup driver"

The build warning hits clang and is a gcc (and C23) extension, and is
fixed up in the merge.

Link: https://lore.kernel.org/all/20240321134831.GA2762840@dev-arch.thelio-3990X/

* tag 'char-misc-6.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (279 commits)
  binder: remove redundant variable page_addr
  uio_dmem_genirq: UIO_MEM_DMA_COHERENT conversion
  uio_pruss: UIO_MEM_DMA_COHERENT conversion
  cnic,bnx2,bnx2x: use UIO_MEM_DMA_COHERENT
  uio: introduce UIO_MEM_DMA_COHERENT type
  cdx: add MSI support for CDX bus
  pps: use cflags-y instead of EXTRA_CFLAGS
  speakup: Add /dev/synthu device
  speakup: Fix 8bit characters from direct synth
  parport: sunbpp: Convert to platform remove callback returning void
  parport: amiga: Convert to platform remove callback returning void
  char: xillybus: Convert to platform remove callback returning void
  vmw_balloon: change maintainership
  MAINTAINERS: change the maintainer for hpilo driver
  char: xilinx_hwicap: Fix NULL vs IS_ERR() bug
  hpet: remove hpets::hp_clocksource
  platform: goldfish: move the separate 'default' propery for CONFIG_GOLDFISH
  char: xilinx_hwicap: drop casting to void in dev_set_drvdata
  greybus: move is_gb_* functions out of greybus.h
  greybus: Remove usage of the deprecated ida_simple_xx() API
  ...
2024-03-21 13:21:31 -07:00
..
obsolete Documentation: ABI: update sysfs-gpio to reference gpio-cdev 2024-01-22 10:49:03 +01:00
removed docs: update ocfs2-devel mailing list address 2023-07-08 09:29:29 -07:00
stable dmaengine: idxd: add wq driver name support for accel-config user tool 2023-10-04 13:00:34 +05:30
testing Char/Misc and other driver subsystem updates for 6.9-rc1 2024-03-21 13:21:31 -07:00
README docs: ABI: README: specify that files should be ReST compatible 2020-10-30 13:07:01 +01:00

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.


Note:
   The fields should be use a simple notation, compatible with ReST markup.
   Also, the file **should not** have a top-level index, like::

	===
	foo
	===

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.