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Ryota Sakamoto 4101b3b571 lib/tests: add KUnit test for bitops
Add a KUnit test suite for the bitops API.

The existing 'lib/test_bitops.c' is preserved as-is because it contains
ad-hoc micro-benchmarks 'test_fns' and is intended to ensure no compiler
warnings from C=1 sparse checker or -Wextra compilations.

Introduce 'lib/tests/bitops_kunit.c' for functional regression testing. It
ports the test logic and data patterns from 'lib/test_bitops.c' to KUnit,
verifying correct behavior across various input patterns and
architecture-specific edge cases using isolated stack-allocated bitmaps.

The following test logic has been ported from test_bitops_startup() in
lib/test_bitops.c:
- set_bit() / clear_bit() / find_first_bit() validation ->
  test_set_bit_clear_bit()
- get_count_order() validation -> test_get_count_order()
- get_count_order_long() validation -> test_get_count_order_long()

Also improve the find_first_bit() test to check the full bitmap length
(BITOPS_LENGTH) instead of omitting the last bit, ensuring the bitmap is
completely empty after cleanup.

Verified on x86_64, i386, and arm64 architectures.

Sample KUnit output:

    KTAP version 1
    # Subtest: bitops
    # module: bitops_kunit
    1..3
        KTAP version 1
        # Subtest: test_set_bit_clear_bit
        ok 1 BITOPS_4
        ok 2 BITOPS_7
        ok 3 BITOPS_11
        ok 4 BITOPS_31
        ok 5 BITOPS_88
    # test_set_bit_clear_bit: pass:5 fail:0 skip:0 total:5
    ok 1 test_set_bit_clear_bit
        KTAP version 1
        # Subtest: test_get_count_order
        ok 1 0x00000003
        ok 2 0x00000004
        ok 3 0x00001fff
        ok 4 0x00002000
        ok 5 0x50000000
        ok 6 0x80000000
        ok 7 0x80003000
    # test_get_count_order: pass:7 fail:0 skip:0 total:7
    ok 2 test_get_count_order
        KTAP version 1
        # Subtest: test_get_count_order_long
        ok 1 0x0000000300000000
        ok 2 0x0000000400000000
        ok 3 0x00001fff00000000
        ok 4 0x0000200000000000
        ok 5 0x5000000000000000
        ok 6 0x8000000000000000
        ok 7 0x8000300000000000
    # test_get_count_order_long: pass:7 fail:0 skip:0 total:7
    ok 3 test_get_count_order_long

[Yury: trim Kconfig help message]

CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Ryota Sakamoto <sakamo.ryota@gmail.com>
Signed-off-by: Yury Norov <ynorov@nvidia.com>
History 2026-02-08 18:47:29 -05:00
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Linux kernel
============

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
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* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
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* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
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============

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* New Kernel Developer - Getting started with kernel development
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For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
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* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
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---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
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* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
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--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
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* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
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Maintainer
----------

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* Maintainer Handbook: Documentation/maintainer/index.rst
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---------------

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* Driver API Guide: Documentation/driver-api/index.rst
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* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

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-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
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=========================

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