linux/Documentation/ABI
Linus Torvalds 857f864014 pci-v4.12-changes
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Merge tag 'pci-v4.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci

Pull PCI updates from Bjorn Helgaas:

 - add framework for supporting PCIe devices in Endpoint mode (Kishon
   Vijay Abraham I)

 - use non-postable PCI config space mappings when possible (Lorenzo
   Pieralisi)

 - clean up and unify mmap of PCI BARs (David Woodhouse)

 - export and unify Function Level Reset support (Christoph Hellwig)

 - avoid FLR for Intel 82579 NICs (Sasha Neftin)

 - add pci_request_irq() and pci_free_irq() helpers (Christoph Hellwig)

 - short-circuit config access failures for disconnected devices (Keith
   Busch)

 - remove D3 sleep delay when possible (Adrian Hunter)

 - freeze PME scan before suspending devices (Lukas Wunner)

 - stop disabling MSI/MSI-X in pci_device_shutdown() (Prarit Bhargava)

 - disable boot interrupt quirk for ASUS M2N-LR (Stefan Assmann)

 - add arch-specific alignment control to improve device passthrough by
   avoiding multiple BARs in a page (Yongji Xie)

 - add sysfs sriov_drivers_autoprobe to control VF driver binding
   (Bodong Wang)

 - allow slots below PCI-to-PCIe "reverse bridges" (Bjorn Helgaas)

 - fix crashes when unbinding host controllers that don't support
   removal (Brian Norris)

 - add driver for MicroSemi Switchtec management interface (Logan
   Gunthorpe)

 - add driver for Faraday Technology FTPCI100 host bridge (Linus
   Walleij)

 - add i.MX7D support (Andrey Smirnov)

 - use generic MSI support for Aardvark (Thomas Petazzoni)

 - make Rockchip driver modular (Brian Norris)

 - advertise 128-byte Read Completion Boundary support for Rockchip
   (Shawn Lin)

 - advertise PCI_EXP_LNKSTA_SLC for Rockchip root port (Shawn Lin)

 - convert atomic_t to refcount_t in HV driver (Elena Reshetova)

 - add CPU IRQ affinity in HV driver (K. Y. Srinivasan)

 - fix PCI bus removal in HV driver (Long Li)

 - add support for ThunderX2 DMA alias topology (Jayachandran C)

 - add ThunderX pass2.x 2nd node MCFG quirk (Tomasz Nowicki)

 - add ITE 8893 bridge DMA alias quirk (Jarod Wilson)

 - restrict Cavium ACS quirk only to CN81xx/CN83xx/CN88xx devices
   (Manish Jaggi)

* tag 'pci-v4.12-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (146 commits)
  PCI: Don't allow unbinding host controllers that aren't prepared
  ARM: DRA7: clockdomain: Change the CLKTRCTRL of CM_PCIE_CLKSTCTRL to SW_WKUP
  MAINTAINERS: Add PCI Endpoint maintainer
  Documentation: PCI: Add userguide for PCI endpoint test function
  tools: PCI: Add sample test script to invoke pcitest
  tools: PCI: Add a userspace tool to test PCI endpoint
  Documentation: misc-devices: Add Documentation for pci-endpoint-test driver
  misc: Add host side PCI driver for PCI test function device
  PCI: Add device IDs for DRA74x and DRA72x
  dt-bindings: PCI: dra7xx: Add DT bindings to enable unaligned access
  PCI: dwc: dra7xx: Workaround for errata id i870
  dt-bindings: PCI: dra7xx: Add DT bindings for PCI dra7xx EP mode
  PCI: dwc: dra7xx: Add EP mode support
  PCI: dwc: dra7xx: Facilitate wrapper and MSI interrupts to be enabled independently
  dt-bindings: PCI: Add DT bindings for PCI designware EP mode
  PCI: dwc: designware: Add EP mode support
  Documentation: PCI: Add binding documentation for pci-test endpoint function
  ixgbe: Use pcie_flr() instead of duplicating it
  IB/hfi1: Use pcie_flr() instead of duplicating it
  PCI: imx6: Fix spelling mistake: "contol" -> "control"
  ...
2017-05-08 19:03:25 -07:00
..
obsolete ACPI / scan: Drop support for force_remove 2017-04-13 03:51:47 +02:00
removed rfkill: Remove obsolete "claim" sysfs interface 2016-02-24 09:04:24 +01:00
stable docs-rst: fix usb cross-references 2017-04-11 14:41:29 -06:00
testing pci-v4.12-changes 2017-05-08 19:03:25 -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.