5 The kernel contains a set of "self tests" under the tools/testing/selftests/
6 directory. These are intended to be small tests to exercise individual code
7 paths in the kernel. Tests are intended to be run after building, installing
10 You can find additional information on Kselftest framework, how to
11 write new tests using the framework on Kselftest wiki:
13 https://kselftest.wiki.kernel.org/
15 On some systems, hot-plug tests could hang forever waiting for cpu and
16 memory to be ready to be offlined. A special hot-plug target is created
17 to run the full range of hot-plug tests. In default mode, hot-plug tests run
18 in safe mode with a limited scope. In limited mode, cpu-hotplug test is
19 run on a single cpu as opposed to all hotplug capable cpus, and memory
20 hotplug test is run on 2% of hotplug capable memory instead of 10%.
22 kselftest runs as a userspace process. Tests that can be written/run in
23 userspace may wish to use the `Test Harness`_. Tests that need to be
24 run in kernel space may wish to use a `Test Module`_.
26 Running the selftests (hotplug tests are run in limited mode)
27 =============================================================
31 $ make -C tools/testing/selftests
35 $ make -C tools/testing/selftests run_tests
37 To build and run the tests with a single command, use::
41 Note that some tests will require root privileges.
43 Kselftest supports saving output files in a separate directory and then
44 running tests. To locate output files in a separate directory two syntaxes
45 are supported. In both cases the working directory must be the root of the
46 kernel src. This is applicable to "Running a subset of selftests" section
49 To build, save output files in a separate directory with O= ::
51 $ make O=/tmp/kselftest kselftest
53 To build, save output files in a separate directory with KBUILD_OUTPUT ::
55 $ export KBUILD_OUTPUT=/tmp/kselftest; make kselftest
57 The O= assignment takes precedence over the KBUILD_OUTPUT environment
60 The above commands by default run the tests and print full pass/fail report.
61 Kselftest supports "summary" option to make it easier to understand the test
62 results. Please find the detailed individual test results for each test in
63 /tmp/testname file(s) when summary option is specified. This is applicable
64 to "Running a subset of selftests" section below.
66 To run kselftest with summary option enabled ::
68 $ make summary=1 kselftest
70 Running a subset of selftests
71 =============================
73 You can use the "TARGETS" variable on the make command line to specify
74 single test to run, or a list of tests to run.
76 To run only tests targeted for a single subsystem::
78 $ make -C tools/testing/selftests TARGETS=ptrace run_tests
80 You can specify multiple tests to build and run::
82 $ make TARGETS="size timers" kselftest
84 To build, save output files in a separate directory with O= ::
86 $ make O=/tmp/kselftest TARGETS="size timers" kselftest
88 To build, save output files in a separate directory with KBUILD_OUTPUT ::
90 $ export KBUILD_OUTPUT=/tmp/kselftest; make TARGETS="size timers" kselftest
92 See the top-level tools/testing/selftests/Makefile for the list of all
95 Running the full range hotplug selftests
96 ========================================
98 To build the hotplug tests::
100 $ make -C tools/testing/selftests hotplug
102 To run the hotplug tests::
104 $ make -C tools/testing/selftests run_hotplug
106 Note that some tests will require root privileges.
112 You can use the kselftest_install.sh tool to install selftests in the
113 default location, which is tools/testing/selftests/kselftest, or in a
114 user specified location.
116 To install selftests in default location::
118 $ cd tools/testing/selftests
119 $ ./kselftest_install.sh
121 To install selftests in a user specified location::
123 $ cd tools/testing/selftests
124 $ ./kselftest_install.sh install_dir
126 Running installed selftests
127 ===========================
129 Kselftest install as well as the Kselftest tarball provide a script
130 named "run_kselftest.sh" to run the tests.
132 You can simply do the following to run the installed Kselftests. Please
133 note some tests will require root privileges::
138 Contributing new tests
139 ======================
141 In general, the rules for selftests are
143 * Do as much as you can if you're not root;
145 * Don't take too long;
147 * Don't break the build on any architecture, and
149 * Don't cause the top-level "make run_tests" to fail if your feature is
152 Contributing new tests (details)
153 ================================
155 * Use TEST_GEN_XXX if such binaries or files are generated during
158 TEST_PROGS, TEST_GEN_PROGS mean it is the executable tested by
161 TEST_CUSTOM_PROGS should be used by tests that require custom build
162 rules and prevent common build rule use.
164 TEST_PROGS are for test shell scripts. Please ensure shell script has
165 its exec bit set. Otherwise, lib.mk run_tests will generate a warning.
167 TEST_CUSTOM_PROGS and TEST_PROGS will be run by common run_tests.
169 TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the
170 executable which is not tested by default.
171 TEST_FILES, TEST_GEN_FILES mean it is the file which is used by
174 * First use the headers inside the kernel source and/or git repo, and then the
175 system headers. Headers for the kernel release as opposed to headers
176 installed by the distro on the system should be the primary focus to be able
179 * If a test needs specific kernel config options enabled, add a config file in
180 the test directory to enable them.
182 e.g: tools/testing/selftests/android/config
187 Kselftest tests the kernel from userspace. Sometimes things need
188 testing from within the kernel, one method of doing this is to create a
189 test module. We can tie the module into the kselftest framework by
190 using a shell script test runner. ``kselftest_module.sh`` is designed
191 to facilitate this process. There is also a header file provided to
192 assist writing kernel modules that are for use with kselftest:
194 - ``tools/testing/kselftest/kselftest_module.h``
195 - ``tools/testing/kselftest/kselftest_module.sh``
200 Here we show the typical steps to create a test module and tie it into
201 kselftest. We use kselftests for lib/ as an example.
203 1. Create the test module
205 2. Create the test script that will run (load/unload) the module
206 e.g. ``tools/testing/selftests/lib/printf.sh``
208 3. Add line to config file e.g. ``tools/testing/selftests/lib/config``
210 4. Add test script to makefile e.g. ``tools/testing/selftests/lib/Makefile``
216 # Assumes you have booted a fresh build of this kernel tree
217 cd /path/to/linux/tree
220 sudo make modules_install
221 make TARGETS=lib kselftest
226 A bare bones test module might look like this:
230 // SPDX-License-Identifier: GPL-2.0+
232 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
234 #include "../tools/testing/selftests/kselftest_module.h"
236 KSTM_MODULE_GLOBALS();
239 * Kernel module for testing the foobinator
242 static int __init test_function()
247 static void __init selftest(void)
249 KSTM_CHECK_ZERO(do_test_case("", 0));
252 KSTM_MODULE_LOADERS(test_foo);
253 MODULE_AUTHOR("John Developer <jd@fooman.org>");
254 MODULE_LICENSE("GPL");
262 # SPDX-License-Identifier: GPL-2.0+
263 $(dirname $0)/../kselftest_module.sh "foo" test_foo
269 The kselftest_harness.h file contains useful helpers to build tests. The
270 test harness is for userspace testing, for kernel space testing see `Test
273 The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as
279 .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
286 .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
287 :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP
288 FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN
293 .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
296 .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
297 :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE
298 ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE
299 ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT
300 EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE
301 EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE