Documentation/dev-tools/kselftest.rst

Source file repositories/reference/linux-study-clean/Documentation/dev-tools/kselftest.rst

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Documentation/dev-tools/kselftest.rst
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Support Tooling And Documentation: documentation
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Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

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======================
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.

Kselftest from mainline can be run on older stable kernels. Running tests
from mainline offers the best coverage. Several test rings run mainline
kselftest suite on stable releases. The reason is that when a new test
gets added to test existing code to regression test a bug, we should be
able to run that test on an older kernel. Hence, it is important to keep
code that can still test an older kernel and make sure it skips the test
gracefully on newer releases.

You can find additional information on Kselftest framework, how to
write new tests using the framework on Kselftest wiki:

https://kselftest.wiki.kernel.org/

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 the 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%.

kselftest runs as a userspace process.  Tests that can be written/run in
userspace may wish to use the `Test Harness`_.  Tests that need to be
run in kernel space may wish to use a `Test Module`_.

Documentation on the tests
==========================

For documentation on the kselftests themselves, see:

.. toctree::

   testing-devices

Running the selftests (hotplug tests are run in limited mode)
=============================================================

To build the tests::

  $ make headers
  $ 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.

Kselftest supports saving output files in a separate directory and then
running tests. To locate output files in a separate directory two syntaxes
are supported. In both cases the working directory must be the root of the
kernel src. This is applicable to "Running a subset of selftests" section
below.

To build, save output files in a separate directory with O= ::

  $ make O=/tmp/kselftest kselftest

Annotation

Implementation Notes