1Linux Kernel Selftests
2
3The kernel contains a set of "self tests" under the tools/testing/selftests/
4directory. These are intended to be small unit tests to exercise individual
5code paths in the kernel.
6
7On some systems, hot-plug tests could hang forever waiting for cpu and
8memory to be ready to be offlined. A special hot-plug target is created
9to run full range of hot-plug tests. In default mode, hot-plug tests run
10in safe mode with a limited scope. In limited mode, cpu-hotplug test is
11run on a single cpu as opposed to all hotplug capable cpus, and memory
12hotplug test is run on 2% of hotplug capable memory instead of 10%.
13
14Running the selftests (hotplug tests are run in limited mode)
15=============================================================
16
17To build the tests:
18  $ make -C tools/testing/selftests
19
20
21To run the tests:
22  $ make -C tools/testing/selftests run_tests
23
24To build and run the tests with a single command, use:
25  $ make kselftest
26
27- note that some tests will require root privileges.
28
29
30Running a subset of selftests
31========================================
32You can use the "TARGETS" variable on the make command line to specify
33single test to run, or a list of tests to run.
34
35To run only tests targeted for a single subsystem:
36  $  make -C tools/testing/selftests TARGETS=ptrace run_tests
37
38You can specify multiple tests to build and run:
39  $  make TARGETS="size timers" kselftest
40
41See the top-level tools/testing/selftests/Makefile for the list of all
42possible targets.
43
44
45Running the full range hotplug selftests
46========================================
47
48To build the hotplug tests:
49  $ make -C tools/testing/selftests hotplug
50
51To run the hotplug tests:
52  $ make -C tools/testing/selftests run_hotplug
53
54- note that some tests will require root privileges.
55
56
57Contributing new tests
58======================
59
60In general, the rules for for selftests are
61
62 * Do as much as you can if you're not root;
63
64 * Don't take too long;
65
66 * Don't break the build on any architecture, and
67
68 * Don't cause the top-level "make run_tests" to fail if your feature is
69   unconfigured.
70