1====================== 2Linux Kernel Selftests 3====================== 4 5The kernel contains a set of "self tests" under the tools/testing/selftests/ 6directory. These are intended to be small tests to exercise individual code 7paths in the kernel. Tests are intended to be run after building, installing 8and booting a kernel. 9 10You can find additional information on Kselftest framework, how to 11write new tests using the framework on Kselftest wiki: 12 13https://kselftest.wiki.kernel.org/ 14 15On some systems, hot-plug tests could hang forever waiting for cpu and 16memory to be ready to be offlined. A special hot-plug target is created 17to run the full range of hot-plug tests. In default mode, hot-plug tests run 18in safe mode with a limited scope. In limited mode, cpu-hotplug test is 19run on a single cpu as opposed to all hotplug capable cpus, and memory 20hotplug test is run on 2% of hotplug capable memory instead of 10%. 21 22Running the selftests (hotplug tests are run in limited mode) 23============================================================= 24 25To build the tests:: 26 27 $ make -C tools/testing/selftests 28 29To run the tests:: 30 31 $ make -C tools/testing/selftests run_tests 32 33To build and run the tests with a single command, use:: 34 35 $ make kselftest 36 37Note that some tests will require root privileges. 38 39Kselftest supports saving output files in a separate directory and then 40running tests. To locate output files in a separate directory two syntaxes 41are supported. In both cases the working directory must be the root of the 42kernel src. This is applicable to "Running a subset of selftests" section 43below. 44 45To build, save output files in a separate directory with O= :: 46 47 $ make O=/tmp/kselftest kselftest 48 49To build, save output files in a separate directory with KBUILD_OUTPUT :: 50 51 $ export KBUILD_OUTPUT=/tmp/kselftest; make kselftest 52 53The O= assignment takes precedence over the KBUILD_OUTPUT environment 54variable. 55 56The above commands by default run the tests and print full pass/fail report. 57Kselftest supports "summary" option to make it easier to understand the test 58results. Please find the detailed individual test results for each test in 59/tmp/testname file(s) when summary option is specified. This is applicable 60to "Running a subset of selftests" section below. 61 62To run kselftest with summary option enabled :: 63 64 $ make summary=1 kselftest 65 66Running a subset of selftests 67============================= 68 69You can use the "TARGETS" variable on the make command line to specify 70single test to run, or a list of tests to run. 71 72To run only tests targeted for a single subsystem:: 73 74 $ make -C tools/testing/selftests TARGETS=ptrace run_tests 75 76You can specify multiple tests to build and run:: 77 78 $ make TARGETS="size timers" kselftest 79 80To build, save output files in a separate directory with O= :: 81 82 $ make O=/tmp/kselftest TARGETS="size timers" kselftest 83 84To build, save output files in a separate directory with KBUILD_OUTPUT :: 85 86 $ export KBUILD_OUTPUT=/tmp/kselftest; make TARGETS="size timers" kselftest 87 88See the top-level tools/testing/selftests/Makefile for the list of all 89possible targets. 90 91Running the full range hotplug selftests 92======================================== 93 94To build the hotplug tests:: 95 96 $ make -C tools/testing/selftests hotplug 97 98To run the hotplug tests:: 99 100 $ make -C tools/testing/selftests run_hotplug 101 102Note that some tests will require root privileges. 103 104 105Install selftests 106================= 107 108You can use the kselftest_install.sh tool to install selftests in the 109default location, which is tools/testing/selftests/kselftest, or in a 110user specified location. 111 112To install selftests in default location:: 113 114 $ cd tools/testing/selftests 115 $ ./kselftest_install.sh 116 117To install selftests in a user specified location:: 118 119 $ cd tools/testing/selftests 120 $ ./kselftest_install.sh install_dir 121 122Running installed selftests 123=========================== 124 125Kselftest install as well as the Kselftest tarball provide a script 126named "run_kselftest.sh" to run the tests. 127 128You can simply do the following to run the installed Kselftests. Please 129note some tests will require root privileges:: 130 131 $ cd kselftest 132 $ ./run_kselftest.sh 133 134Contributing new tests 135====================== 136 137In general, the rules for selftests are 138 139 * Do as much as you can if you're not root; 140 141 * Don't take too long; 142 143 * Don't break the build on any architecture, and 144 145 * Don't cause the top-level "make run_tests" to fail if your feature is 146 unconfigured. 147 148Contributing new tests (details) 149================================ 150 151 * Use TEST_GEN_XXX if such binaries or files are generated during 152 compiling. 153 154 TEST_PROGS, TEST_GEN_PROGS mean it is the executable tested by 155 default. 156 157 TEST_CUSTOM_PROGS should be used by tests that require custom build 158 rules and prevent common build rule use. 159 160 TEST_PROGS are for test shell scripts. Please ensure shell script has 161 its exec bit set. Otherwise, lib.mk run_tests will generate a warning. 162 163 TEST_CUSTOM_PROGS and TEST_PROGS will be run by common run_tests. 164 165 TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the 166 executable which is not tested by default. 167 TEST_FILES, TEST_GEN_FILES mean it is the file which is used by 168 test. 169 170 * First use the headers inside the kernel source and/or git repo, and then the 171 system headers. Headers for the kernel release as opposed to headers 172 installed by the distro on the system should be the primary focus to be able 173 to find regressions. 174 175 * If a test needs specific kernel config options enabled, add a config file in 176 the test directory to enable them. 177 178 e.g: tools/testing/selftests/android/config 179 180Test Harness 181============ 182 183The kselftest_harness.h file contains useful helpers to build tests. The tests 184from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example. 185 186Example 187------- 188 189.. kernel-doc:: tools/testing/selftests/kselftest_harness.h 190 :doc: example 191 192 193Helpers 194------- 195 196.. kernel-doc:: tools/testing/selftests/kselftest_harness.h 197 :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP 198 FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN 199 200Operators 201--------- 202 203.. kernel-doc:: tools/testing/selftests/kselftest_harness.h 204 :doc: operators 205 206.. kernel-doc:: tools/testing/selftests/kselftest_harness.h 207 :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE 208 ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE 209 ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT 210 EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE 211 EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE 212