Linux Kernel Selftests
The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small tests to exercise individual code paths in the kernel. Tests are intended to be run after building, installing and booting a kernel.
On some systems, hot-plug tests could hang forever waiting for cpu and memory to be ready to be offlined. A special hot-plug target is created to run full range of hot-plug tests. In default mode, hot-plug tests run in safe mode with a limited scope. In limited mode, cpu-hotplug test is run on a single cpu as opposed to all hotplug capable cpus, and memory hotplug test is run on 2% of hotplug capable memory instead of 10%.
Running the selftests (hotplug tests are run in limited mode)
To build the tests:
$ make -C tools/testing/selftests
To run the tests:
$ make -C tools/testing/selftests run_tests
To build and run the tests with a single command, use:
$ make kselftest
Note that some tests will require root privileges.
Running a subset of selftests
You can use the "TARGETS" variable on the make command line to specify single test to run, or a list of tests to run.
To run only tests targeted for a single subsystem:
$ make -C tools/testing/selftests TARGETS=ptrace run_tests
You can specify multiple tests to build and run:
$ make TARGETS="size timers" kselftest
See the top-level tools/testing/selftests/Makefile for the list of all possible targets.
Running the full range hotplug selftests
To build the hotplug tests:
$ make -C tools/testing/selftests hotplug
To run the hotplug tests:
$ make -C tools/testing/selftests run_hotplug
Note that some tests will require root privileges.
Install selftests
You can use kselftest_install.sh tool installs selftests in default location which is tools/testing/selftests/kselftest or a user specified location.
To install selftests in default location:
$ cd tools/testing/selftests $ ./kselftest_install.sh
To install selftests in a user specified location:
$ cd tools/testing/selftests $ ./kselftest_install.sh install_dir
Running installed selftests
Kselftest install as well as the Kselftest tarball provide a script named "run_kselftest.sh" to run the tests.
You can simply do the following to run the installed Kselftests. Please note some tests will require root privileges:
$ cd kselftest $ ./run_kselftest.sh
Contributing new tests
In general, the rules for selftests are
- Do as much as you can if you're not root;
- Don't take too long;
- Don't break the build on any architecture, and
- Don't cause the top-level "make run_tests" to fail if your feature is unconfigured.
Contributing new tests (details)
Use TEST_GEN_XXX if such binaries or files are generated during compiling.
TEST_PROGS, TEST_GEN_PROGS mean it is the excutable tested by default.
TEST_PROGS_EXTENDED, TEST_GEN_PROGS_EXTENDED mean it is the executable which is not tested by default. TEST_FILES, TEST_GEN_FILES mean it is the file which is used by test.
Test Harness
The kselftest_harness.h file contains useful helpers to build tests. The tests from tools/testing/selftests/seccomp/seccomp_bpf.c can be used as example.