linux/Documentation/ABI
Linus Torvalds 46b407ca4a remoteproc/rpmsg: new subsystem
This new subsystem provides a common way to talk to secondary processors
 on an SoC, e.g. a DSP, GPU or service processor, using virtio as the
 transport. In the long run, it should replace a few dozen vendor
 specific ways to do the same thing, which all never made it into the
 upstream kernel. There is a broad agreement that rpmsg is the way to
 go here and several vendors have started working on replacing their
 own subsystems.
 
 Two branches each add one virtio protocol number. Fortunately the
 numbers were agreed upon in advance, so there are only context changes.
 
 Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Merge tag 'rpmsg' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

Pull "remoteproc/rpmsg: new subsystem" from Arnd Bergmann:
 "This new subsystem provides a common way to talk to secondary
  processors on an SoC, e.g.  a DSP, GPU or service processor, using
  virtio as the transport.  In the long run, it should replace a few
  dozen vendor specific ways to do the same thing, which all never made
  it into the upstream kernel.  There is a broad agreement that rpmsg is
  the way to go here and several vendors have started working on
  replacing their own subsystems.

  Two branches each add one virtio protocol number.  Fortunately the
  numbers were agreed upon in advance, so there are only context
  changes.

  Signed-off-by: Arnd Bergmann <arnd@arndb.de>"

Fixed up trivial protocol number conflict due to the mentioned additions
next to each other.

* tag 'rpmsg' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (32 commits)
  remoteproc: cleanup resource table parsing paths
  remoteproc: remove the hardcoded vring alignment
  remoteproc/omap: remove the mbox_callback limitation
  remoteproc: remove the single rpmsg vdev limitation
  remoteproc: safer boot/shutdown order
  remoteproc: remoteproc_rpmsg -> remoteproc_virtio
  remoteproc: resource table overhaul
  rpmsg: fix build warning when dma_addr_t is 64-bit
  rpmsg: fix published buffer length in rpmsg_recv_done
  rpmsg: validate incoming message length before propagating
  rpmsg: fix name service endpoint leak
  remoteproc/omap: two Kconfig fixes
  remoteproc: make sure we're parsing a 32bit firmware
  remoteproc: s/big switch/lookup table/
  remoteproc: bail out if firmware has different endianess
  remoteproc: don't use virtio's weak barriers
  rpmsg: rename virtqueue_add_buf_gfp to virtqueue_add_buf
  rpmsg: depend on EXPERIMENTAL
  remoteproc: depend on EXPERIMENTAL
  rpmsg: add Kconfig menu
  ...

Conflicts:
	include/linux/virtio_ids.h
2012-03-27 16:30:09 -07:00
..
obsolete Documentation: Fix multiple typo in Documentation 2012-03-07 16:08:24 +01:00
removed driver-core: documentation: fix up Greg's email address 2012-02-15 14:48:01 -08:00
stable Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2012-03-20 21:12:50 -07:00
testing remoteproc/rpmsg: new subsystem 2012-03-27 16:30:09 -07:00
README [PATCH] Add kernel<->userspace ABI stability documentation 2006-06-21 12:40:47 -07:00

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.
	The file Documentation/feature-removal-schedule.txt may describe
	some of these interfaces, giving a schedule for when they will
	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.