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authorGreg Kroah-Hartman <gregkh@suse.de>2006-04-27 17:10:12 -0400
committerGreg Kroah-Hartman <gregkh@suse.de>2006-06-21 15:40:47 -0400
commitc18f6365fdbaf30611a8822afcd7097865dcaa32 (patch)
treefb136fffab80d3022edcc4fc17b3da789eb7b838 /Documentation/ABI
parent183bd5b3da82b80920c30c4772222df8027fc364 (diff)
[PATCH] Add kernel<->userspace ABI stability documentation
Signed-off-by: Kay Sievers <kay.sievers@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/README77
-rw-r--r--Documentation/ABI/obsolete/devfs13
-rw-r--r--Documentation/ABI/stable/syscalls10
-rw-r--r--Documentation/ABI/stable/sysfs-module30
-rw-r--r--Documentation/ABI/testing/sysfs-class16
-rw-r--r--Documentation/ABI/testing/sysfs-devices25
6 files changed, 171 insertions, 0 deletions
diff --git a/Documentation/ABI/README b/Documentation/ABI/README
new file mode 100644
index 000000000000..9feaf16f1617
--- /dev/null
+++ b/Documentation/ABI/README
@@ -0,0 +1,77 @@
1This directory attempts to document the ABI between the Linux kernel and
2userspace, and the relative stability of these interfaces. Due to the
3everchanging nature of Linux, and the differing maturity levels, these
4interfaces should be used by userspace programs in different ways.
5
6We have four different levels of ABI stability, as shown by the four
7different subdirectories in this location. Interfaces may change levels
8of stability according to the rules described below.
9
10The different levels of stability are:
11
12 stable/
13 This directory documents the interfaces that the developer has
14 defined to be stable. Userspace programs are free to use these
15 interfaces with no restrictions, and backward compatibility for
16 them will be guaranteed for at least 2 years. Most interfaces
17 (like syscalls) are expected to never change and always be
18 available.
19
20 testing/
21 This directory documents interfaces that are felt to be stable,
22 as the main development of this interface has been completed.
23 The interface can be changed to add new features, but the
24 current interface will not break by doing this, unless grave
25 errors or security problems are found in them. Userspace
26 programs can start to rely on these interfaces, but they must be
27 aware of changes that can occur before these interfaces move to
28 be marked stable. Programs that use these interfaces are
29 strongly encouraged to add their name to the description of
30 these interfaces, so that the kernel developers can easily
31 notify them if any changes occur (see the description of the
32 layout of the files below for details on how to do this.)
33
34 obsolete/
35 This directory documents interfaces that are still remaining in
36 the kernel, but are marked to be removed at some later point in
37 time. The description of the interface will document the reason
38 why it is obsolete and when it can be expected to be removed.
39 The file Documentation/feature-removal-schedule.txt may describe
40 some of these interfaces, giving a schedule for when they will
41 be removed.
42
43 removed/
44 This directory contains a list of the old interfaces that have
45 been removed from the kernel.
46
47Every file in these directories will contain the following information:
48
49What: Short description of the interface
50Date: Date created
51KernelVersion: Kernel version this feature first showed up in.
52Contact: Primary contact for this interface (may be a mailing list)
53Description: Long description of the interface and how to use it.
54Users: All users of this interface who wish to be notified when
55 it changes. This is very important for interfaces in
56 the "testing" stage, so that kernel developers can work
57 with userspace developers to ensure that things do not
58 break in ways that are unacceptable. It is also
59 important to get feedback for these interfaces to make
60 sure they are working in a proper way and do not need to
61 be changed further.
62
63
64How things move between levels:
65
66Interfaces in stable may move to obsolete, as long as the proper
67notification is given.
68
69Interfaces may be removed from obsolete and the kernel as long as the
70documented amount of time has gone by.
71
72Interfaces in the testing state can move to the stable state when the
73developers feel they are finished. They cannot be removed from the
74kernel tree without going through the obsolete state first.
75
76It's up to the developer to place their interfaces in the category they
77wish for it to start out in.
diff --git a/Documentation/ABI/obsolete/devfs b/Documentation/ABI/obsolete/devfs
new file mode 100644
index 000000000000..b8b87399bc8f
--- /dev/null
+++ b/Documentation/ABI/obsolete/devfs
@@ -0,0 +1,13 @@
1What: devfs
2Date: July 2005
3Contact: Greg Kroah-Hartman <gregkh@suse.de>
4Description:
5 devfs has been unmaintained for a number of years, has unfixable
6 races, contains a naming policy within the kernel that is
7 against the LSB, and can be replaced by using udev.
8 The files fs/devfs/*, include/linux/devfs_fs*.h will be removed,
9 along with the the assorted devfs function calls throughout the
10 kernel tree.
11
12Users:
13
diff --git a/Documentation/ABI/stable/syscalls b/Documentation/ABI/stable/syscalls
new file mode 100644
index 000000000000..c3ae3e7d6a0c
--- /dev/null
+++ b/Documentation/ABI/stable/syscalls
@@ -0,0 +1,10 @@
1What: The kernel syscall interface
2Description:
3 This interface matches much of the POSIX interface and is based
4 on it and other Unix based interfaces. It will only be added to
5 over time, and not have things removed from it.
6
7 Note that this interface is different for every architecture
8 that Linux supports. Please see the architecture-specific
9 documentation for details on the syscall numbers that are to be
10 mapped to each syscall.
diff --git a/Documentation/ABI/stable/sysfs-module b/Documentation/ABI/stable/sysfs-module
new file mode 100644
index 000000000000..75be43118335
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-module
@@ -0,0 +1,30 @@
1What: /sys/module
2Description:
3 The /sys/module tree consists of the following structure:
4
5 /sys/module/MODULENAME
6 The name of the module that is in the kernel. This
7 module name will show up either if the module is built
8 directly into the kernel, or if it is loaded as a
9 dyanmic module.
10
11 /sys/module/MODULENAME/parameters
12 This directory contains individual files that are each
13 individual parameters of the module that are able to be
14 changed at runtime. See the individual module
15 documentation as to the contents of these parameters and
16 what they accomplish.
17
18 Note: The individual parameter names and values are not
19 considered stable, only the fact that they will be
20 placed in this location within sysfs. See the
21 individual driver documentation for details as to the
22 stability of the different parameters.
23
24 /sys/module/MODULENAME/refcnt
25 If the module is able to be unloaded from the kernel, this file
26 will contain the current reference count of the module.
27
28 Note: If the module is built into the kernel, or if the
29 CONFIG_MODULE_UNLOAD kernel configuration value is not enabled,
30 this file will not be present.
diff --git a/Documentation/ABI/testing/sysfs-class b/Documentation/ABI/testing/sysfs-class
new file mode 100644
index 000000000000..4b0cb891e46e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class
@@ -0,0 +1,16 @@
1What: /sys/class/
2Date: Febuary 2006
3Contact: Greg Kroah-Hartman <gregkh@suse.de>
4Description:
5 The /sys/class directory will consist of a group of
6 subdirectories describing individual classes of devices
7 in the kernel. The individual directories will consist
8 of either subdirectories, or symlinks to other
9 directories.
10
11 All programs that use this directory tree must be able
12 to handle both subdirectories or symlinks in order to
13 work properly.
14
15Users:
16 udev <linux-hotplug-devel@lists.sourceforge.net>
diff --git a/Documentation/ABI/testing/sysfs-devices b/Documentation/ABI/testing/sysfs-devices
new file mode 100644
index 000000000000..6a25671ee5f6
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-devices
@@ -0,0 +1,25 @@
1What: /sys/devices
2Date: February 2006
3Contact: Greg Kroah-Hartman <gregkh@suse.de>
4Description:
5 The /sys/devices tree contains a snapshot of the
6 internal state of the kernel device tree. Devices will
7 be added and removed dynamically as the machine runs,
8 and between different kernel versions, the layout of the
9 devices within this tree will change.
10
11 Please do not rely on the format of this tree because of
12 this. If a program wishes to find different things in
13 the tree, please use the /sys/class structure and rely
14 on the symlinks there to point to the proper location
15 within the /sys/devices tree of the individual devices.
16 Or rely on the uevent messages to notify programs of
17 devices being added and removed from this tree to find
18 the location of those devices.
19
20 Note that sometimes not all devices along the directory
21 chain will have emitted uevent messages, so userspace
22 programs must be able to handle such occurrences.
23
24Users:
25 udev <linux-hotplug-devel@lists.sourceforge.net>