======================

  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.
  
  Example
  -------
  
  .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
      :doc: example
  
  
  Helpers
  -------
  
  .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
      :functions: TH_LOG TEST TEST_SIGNAL FIXTURE FIXTURE_DATA FIXTURE_SETUP
                  FIXTURE_TEARDOWN TEST_F TEST_HARNESS_MAIN
  
  Operators
  ---------
  
  .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
      :doc: operators
  
  .. kernel-doc:: tools/testing/selftests/kselftest_harness.h
      :functions: ASSERT_EQ ASSERT_NE ASSERT_LT ASSERT_LE ASSERT_GT ASSERT_GE
                  ASSERT_NULL ASSERT_TRUE ASSERT_NULL ASSERT_TRUE ASSERT_FALSE
                  ASSERT_STREQ ASSERT_STRNE EXPECT_EQ EXPECT_NE EXPECT_LT
                  EXPECT_LE EXPECT_GT EXPECT_GE EXPECT_NULL EXPECT_TRUE
                  EXPECT_FALSE EXPECT_STREQ EXPECT_STRNE