linux/Documentation/ABI
Linus Torvalds 457fa3469a Char/Misc driver patches for 4.21-rc1
Here is the big set of char and misc driver patches for 4.21-rc1.
 
 Lots of different types of driver things in here, as this tree seems to
 be the "collection of various driver subsystems not big enough to have
 their own git tree" lately.
 
 Anyway, some highlights of the changes in here:
   - binderfs: is it a rule that all driver subsystems will eventually
     grow to have their own filesystem?  Binder now has one to handle the
     use of it in containerized systems.  This was discussed at the
     Plumbers conference a few months ago and knocked into mergable shape
     very fast by Christian Brauner.  Who also has signed up to be
     another binder maintainer, showing a distinct lack of good judgement :)
   - binder updates and fixes
   - mei driver updates
   - fpga driver updates and additions
   - thunderbolt driver updates
   - soundwire driver updates
   - extcon driver updates
   - nvmem driver updates
   - hyper-v driver updates
   - coresight driver updates
   - pvpanic driver additions and reworking for more device support
   - lp driver updates.  Yes really, it's _finally_ moved to the proper
     parallal port driver model, something I never thought I would see
     happen.  Good stuff.
   - other tiny driver updates and fixes.
 
 All of these have been in linux-next for a while with no reported
 issues.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'char-misc-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc

Pull char/misc driver updates from Greg KH:
 "Here is the big set of char and misc driver patches for 4.21-rc1.

  Lots of different types of driver things in here, as this tree seems
  to be the "collection of various driver subsystems not big enough to
  have their own git tree" lately.

  Anyway, some highlights of the changes in here:

   - binderfs: is it a rule that all driver subsystems will eventually
     grow to have their own filesystem? Binder now has one to handle the
     use of it in containerized systems.

     This was discussed at the Plumbers conference a few months ago and
     knocked into mergable shape very fast by Christian Brauner. Who
     also has signed up to be another binder maintainer, showing a
     distinct lack of good judgement :)

   - binder updates and fixes

   - mei driver updates

   - fpga driver updates and additions

   - thunderbolt driver updates

   - soundwire driver updates

   - extcon driver updates

   - nvmem driver updates

   - hyper-v driver updates

   - coresight driver updates

   - pvpanic driver additions and reworking for more device support

   - lp driver updates. Yes really, it's _finally_ moved to the proper
     parallal port driver model, something I never thought I would see
     happen. Good stuff.

   - other tiny driver updates and fixes.

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

* tag 'char-misc-4.21-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (116 commits)
  MAINTAINERS: add another Android binder maintainer
  intel_th: msu: Fix an off-by-one in attribute store
  stm class: Add a reference to the SyS-T document
  stm class: Fix a module refcount leak in policy creation error path
  char: lp: use new parport device model
  char: lp: properly count the lp devices
  char: lp: use first unused lp number while registering
  char: lp: detach the device when parallel port is removed
  char: lp: introduce list to save port number
  bus: qcom: remove duplicated include from qcom-ebi2.c
  VMCI: Use memdup_user() rather than duplicating its implementation
  char/rtc: Use of_node_name_eq for node name comparisons
  misc: mic: fix a DMA pool free failure
  ptp: fix an IS_ERR() vs NULL check
  genwqe: Fix size check
  binder: implement binderfs
  binder: fix use-after-free due to ksys_close() during fdget()
  bus: fsl-mc: remove duplicated include files
  bus: fsl-mc: explicitly define the fsl_mc_command endianness
  misc: ti-st: make array read_ver_cmd static, shrinks object size
  ...
2018-12-28 20:54:57 -08:00
..
obsolete usb: typec: Bus type for alternate modes 2018-07-02 17:42:36 +02:00
removed acpi, nfit: Remove ecc_unit_size 2018-06-03 12:49:15 -07:00
stable Documentation/ABI: Add new attribute for mlxreg-io sysfs interfaces 2018-12-10 17:54:41 -08:00
testing Char/Misc driver patches for 4.21-rc1 2018-12-28 20:54:57 -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.


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.