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Linus Torvalds 36492b7141 Detect unused tracepoints for v6.19:
If a tracepoint is defined but never used (TRACE_EVENT() created but no
 trace_<tracepoint>() called), it can take up to or more than 5K of memory
 each. This can add up as there are around a hundred unused tracepoints with
 various configs. That is 500K of wasted memory.
 
 Add a make build parameter of "UT=1" to have the build warn if an unused
 tracepoint is detected in the build. This allows detection of unused
 tracepoints to be upstream so that outreachy and the mentoring project can
 have new developers look for fixing them, without having these warnings
 suddenly show up when someone upgrades their kernel. When all known unused
 tracepoints are removed, then the "UT=1" build parameter can be removed and
 unused tracepoints will always warn. This will catch new unused tracepoints
 after the current ones have been removed.
 
 - Separate out elf functions from sorttable.c
 
   Move out the ELF parsing functions from sorttable.c so that the tracing
   tooling can use it.
 
 - Add a tracepoint verifier tool to the build process
 
   If "UT=1" is added to the kernel command line, any unused tracepoints will
   trigger a warning at build time.
 
 - Do not warn about unused tracepoints for tracepoints that are exported
 
   There are sever cases where a tracepoint is created by the kernel and used
   by modules. Since there's no easy way to detect if these are truly unused
   since the users are in modules, if a tracepoint is exported, assume it
   will eventually be used by a module. Note, there's not many exported
   tracepoints so this should not be a problem to ignore them.
 
 - Have building of modules also detect unused tracepoints
 
   Do not only check the main vmlinux for unused tracepoints, also check
   modules. If a module is defining a tracepoint it should be using it.
 
 - Add the tracepoint-update program to the ignore file
 
   The new tracepoint-update program needs to be ignored by git.
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Merge tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull unused tracepoints update from Steven Rostedt:
 "Detect unused tracepoints.

  If a tracepoint is defined but never used (TRACE_EVENT() created but
  no trace_<tracepoint>() called), it can take up to or more than 5K of
  memory each. This can add up as there are around a hundred unused
  tracepoints with various configs. That is 500K of wasted memory.

  Add a make build parameter of "UT=1" to have the build warn if an
  unused tracepoint is detected in the build. This allows detection of
  unused tracepoints to be upstream so that outreachy and the mentoring
  project can have new developers look for fixing them, without having
  these warnings suddenly show up when someone upgrades their kernel.

  When all known unused tracepoints are removed, then the "UT=1" build
  parameter can be removed and unused tracepoints will always warn. This
  will catch new unused tracepoints after the current ones have been
  removed.

  Summary:

   - Separate out elf functions from sorttable.c

     Move out the ELF parsing functions from sorttable.c so that the
     tracing tooling can use it.

   - Add a tracepoint verifier tool to the build process

     If "UT=1" is added to the kernel command line, any unused
     tracepoints will trigger a warning at build time.

   - Do not warn about unused tracepoints for tracepoints that are
     exported

     There are sever cases where a tracepoint is created by the kernel
     and used by modules. Since there's no easy way to detect if these
     are truly unused since the users are in modules, if a tracepoint is
     exported, assume it will eventually be used by a module. Note,
     there's not many exported tracepoints so this should not be a
     problem to ignore them.

   - Have building of modules also detect unused tracepoints

     Do not only check the main vmlinux for unused tracepoints, also
     check modules. If a module is defining a tracepoint it should be
     using it.

   - Add the tracepoint-update program to the ignore file

     The new tracepoint-update program needs to be ignored by git"

* tag 'tracepoints-v6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  scripts: add tracepoint-update to the list of ignores files
  tracing: Add warnings for unused tracepoints for modules
  tracing: Allow tracepoint-update.c to work with modules
  tracepoint: Do not warn for unused event that is exported
  tracing: Add a tracepoint verification check at build time
  sorttable: Move ELF parsing into scripts/elf-parse.[ch]
2025-12-05 09:37:41 -08:00
Documentation rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
LICENSES LICENSES: Replace the obsolete address of the FSF in the GFDL-1.2 2025-07-24 11:15:39 +02:00
arch IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
block VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
certs sign-file,extract-cert: use pkcs11 provider for OPENSSL MAJOR >= 3 2024-09-20 19:52:48 +03:00
crypto Networking changes for 6.19. 2025-12-03 17:24:33 -08:00
drivers hardening updates for v6.19-rc1 2025-12-05 09:11:02 -08:00
fs pstore update for v6.19-rc1 2025-12-05 09:08:13 -08:00
include Detect unused tracepoints for v6.19: 2025-12-05 09:37:41 -08:00
init drm-next for 6.19-rc1: 2025-12-04 08:53:30 -08:00
io_uring for-6.19/io_uring-20251201 2025-12-03 18:58:57 -08:00
ipc vfs-6.19-rc1.fd_prepare.fs 2025-12-01 17:32:07 -08:00
kernel VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
lib sound updates for 6.19-rc1 2025-12-04 10:08:40 -08:00
mm VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
net for-6.19/io_uring-20251201 2025-12-03 18:58:57 -08:00
rust pwm: Changes for v6.19-rc1 2025-12-04 11:04:38 -08:00
samples VFIO updates for v6.19-rc1 2025-12-04 18:42:48 -08:00
scripts Detect unused tracepoints for v6.19: 2025-12-05 09:37:41 -08:00
security Capabilities patch for v6.19 2025-12-04 20:10:28 -08:00
sound firewire updates for v6.19 2025-12-04 12:26:36 -08:00
tools rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
usr initramfs: add gen_init_cpio to hostprogs unconditionally 2025-11-26 21:55:40 +01:00
virt A large overhaul of the restartable sequences and CID management: 2025-12-02 08:48:53 -08:00
.clang-format IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about `clippy::disallowed_macros` configuration 2025-05-07 00:11:47 +02:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap IOMMU Updates for Linux v6.19 2025-12-04 18:05:06 -08:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS MAINTAINERS: mark ISDN subsystem as orphan 2025-10-27 17:49:45 -07:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS rtla updaets for v6.19: 2025-12-05 09:34:01 -08:00
Makefile Detect unused tracepoints for v6.19: 2025-12-05 09:37:41 -08:00
README README: restructure with role-based documentation and guidelines 2025-11-29 08:40:33 -07:00

README

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
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

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

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer - Getting started with kernel development
* Academic Researcher - Studying kernel internals and architecture
* Security Expert - Hardening and vulnerability analysis
* Backport/Maintenance Engineer - Maintaining stable kernels
* System Administrator - Configuring and troubleshooting
* Maintainer - Leading subsystems and reviewing patches
* Hardware Vendor - Writing drivers for new hardware
* Distribution Maintainer - Packaging kernels for distros


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
* Build System: Documentation/kbuild/index.rst
* 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
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

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
* CVE Procedures: Documentation/process/cve.rst
* 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
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

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
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst



Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst