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Linus Torvalds df37e39242 Power management updates for 7.4-rc1
- Fix multiple issues related to input validation, synchronization,
    access safety, memory layout and register field validation, and error
    handling in the ACPI CPPC library (Christian Loehle and Sumit Gupta)
 
  - Select the frequency-invariance callback per CPU in the CPPC cpufreq
    driver and create the FIE worker before enabling PCC callbacks in it
    to avoid queueing work through a missing worker and dereferencing a
    NULL pointer (Christian Loehle)
 
  - Update the CPPC cpufreq driver entry in MAINTAINERS and add a new
    entry for the ACPI CPPC library (Christian Loehle)
 
  - Minor fixes in various cpufreq drivers (Alexander Koskovich, Daniel
    Schwierzeck, Frank Zhang, Haotian Zhang, Kathiravan Thirumoorthy,
    Sumeet Pawnikar, and Xueqin Luo)
 
  - Fix wrong behaviors on multi-node servers in the Loongson cpufreq
    driver (Huacai Chen)
 
  - Reject NULL from cpufreq_cpu_get() in the Rust code (Mehmet Koseoglu)
 
  - Add suspend OPP to mediatek cpufreq driver and DT (Ryan Brue)
 
  - Fixups for a few bugs identified by Sashiko in the amd-pstate cpufreq
    driver (Mario Limoncielloi, Wentao Guan)
 
  - Initial support for maximum frequency capacity handling on Zen6
    client in amd-pstate (Mario Limonciello)
 
  - Fix for amd-pstate-ut with 'Requested CPU Min frequency' BIOS option
    (K Prateek Nayak)
 
  - New Zen6 tuning values for EPP in amd-pstate (Mario Limonciello,
    Vishal Badole)
 
  - amd-pstate documentation fix (Karl Mehltretter)
 
  - Restrict deferred downscaling to low load for shared policies in the
    conservative cpufreq governor to avoid undesirable CPU frequency
    reduction in some cases (Shengming Hu)
 
  - Serialize sugov_start() against rate limit updates in the schedutil
    cpufreq governor to avoid using a stale rate limit value (Hui Su)
 
  - Prevent cpuidle governors menu and teo from returning idle state 0
    after it has been disabled (Xueqin Luo)
 
  - Replace min_t() with the better alternatives in the intel_idle driver
    and make it use 2-argument strscpy() (Andy Shevchenko)
 
  - Fix two repeated phrase instances in cpuidle (Hemanth Selam, Syazwina
    Fazrul)
 
  - Add rugged Panther Lake support to the intel_rapl power capping
    driver and make it use %pe for printing error pointers (Srinivas
    Pandruvada and Sumeet Pawnikar)
 
  - Update and improve runtime PM documentation and add a kunit test for
    supplier idle/suspend (Brian Norris)
 
  - Add a pm_runtime_dont_use_autosuspend() call to pm_runtime_reinit()
    to ensure autosuspend disabling on driver teardown (Joshua Crofts)
 
  - Ignore page-zero RAM in E820 checksum during hibernation on x86 to
    avoid rejecting images created after kexec() (Matthias Goergens)
 
  - Add resume event mapping for PMSG_POWEROFF to the PM core to allow it
    to carry out device shutdown in the future (Mario Limonciello)
 
  - Add DPM watchdog to prepare/late/early/noirq/complete phases of
    device suspend and resume (Mayank Rungta)
 
  - Update swsusp.txt references to swsusp.rst in hibernation
    documentation (Li Jun)
 
  - Fix use-after-free of perf domain in netlink doit handlers for energy
    models (Fan Wu)
 
  - Add synchronize_rcu() back to cpu_pm_unregister_notifier() after it
    was removed inadvertently in previous development cycles to avoid
    use-after-free (Bradley Morgan)
 
  - Unregister CPU PM notifier outside the timer lock in the timer-ti-dm
    clocksource driver (Bradley Morgan)
 
  - Fix typo "sucessfully" in a comment in pm_clk_add_clk() kerneldoc
    comment and typo "hierachy" in a comment in pm-graph (Hemanth Selam)
 
  - Fix the return value in dev_pm_opp_get_of_node() kernel-doc (Karl
    Mehltretter)
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Merge tag 'pm-7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull power management updates from Rafael Wysocki:
 "This time, the most visible part are the ACPI CPPC updates from
  Christian Loehle, including CPPC cpufreq driver changes, even though
  updates of cpufreq drivers proper are still the largest topic group.
  However, the updates of cpufreq drivers depend on the ACPI CPPC
  updates, so they should really be counted together and that is well
  over 1/2 of the total commit count.

  Interestingly enough, almost all of the updates included here are
  fixes or cleanups, with some new feature support in the amd-pstate
  cpufreq driver and IPQ9650 support in the qcom-nvmem cpufreq driver.
  The runtime PM documentation improvements from Brian Norris can also
  be mostly regarded as fixes, but a new kunit test goes along with
  them.

  Specifics:

   - Fix multiple issues related to input validation, synchronization,
     access safety, memory layout and register field validation, and
     error handling in the ACPI CPPC library (Christian Loehle and Sumit
     Gupta)

   - Select the frequency-invariance callback per CPU in the CPPC
     cpufreq driver and create the FIE worker before enabling PCC
     callbacks in it to avoid queueing work through a missing worker and
     dereferencing a NULL pointer (Christian Loehle)

   - Update the CPPC cpufreq driver entry in MAINTAINERS and add a new
     entry for the ACPI CPPC library (Christian Loehle)

   - Minor fixes in various cpufreq drivers (Alexander Koskovich, Daniel
     Schwierzeck, Frank Zhang, Haotian Zhang, Kathiravan Thirumoorthy,
     Sumeet Pawnikar, and Xueqin Luo)

   - Fix wrong behaviors on multi-node servers in the Loongson cpufreq
     driver (Huacai Chen)

   - Reject NULL from cpufreq_cpu_get() in the Rust code (Mehmet
     Koseoglu)

   - Add suspend OPP to mediatek cpufreq driver and DT (Ryan Brue)

   - Fixups for a few bugs identified by Sashiko in the amd-pstate
     cpufreq driver (Mario Limoncielloi, Wentao Guan)

   - Initial support for maximum frequency capacity handling on Zen6
     client in amd-pstate (Mario Limonciello)

   - Fix for amd-pstate-ut with 'Requested CPU Min frequency' BIOS
     option (K Prateek Nayak)

   - New Zen6 tuning values for EPP in amd-pstate (Mario Limonciello,
     Vishal Badole)

   - amd-pstate documentation fix (Karl Mehltretter)

   - Restrict deferred downscaling to low load for shared policies in
     the conservative cpufreq governor to avoid undesirable CPU
     frequency reduction in some cases (Shengming Hu)

   - Serialize sugov_start() against rate limit updates in the schedutil
     cpufreq governor to avoid using a stale rate limit value (Hui Su)

   - Prevent cpuidle governors menu and teo from returning idle state 0
     after it has been disabled (Xueqin Luo)

   - Replace min_t() with the better alternatives in the intel_idle
     driver and make it use 2-argument strscpy() (Andy Shevchenko)

   - Fix two repeated phrase instances in cpuidle (Hemanth Selam,
     Syazwina Fazrul)

   - Add rugged Panther Lake support to the intel_rapl power capping
     driver and make it use %pe for printing error pointers (Srinivas
     Pandruvada and Sumeet Pawnikar)

   - Update and improve runtime PM documentation and add a kunit test
     for supplier idle/suspend (Brian Norris)

   - Add a pm_runtime_dont_use_autosuspend() call to pm_runtime_reinit()
     to ensure autosuspend disabling on driver teardown (Joshua Crofts)

   - Ignore page-zero RAM in E820 checksum during hibernation on x86 to
     avoid rejecting images created after kexec() (Matthias Goergens)

   - Add resume event mapping for PMSG_POWEROFF to the PM core to allow
     it to carry out device shutdown in the future (Mario Limonciello)

   - Add DPM watchdog to prepare/late/early/noirq/complete phases of
     device suspend and resume (Mayank Rungta)

   - Update swsusp.txt references to swsusp.rst in hibernation
     documentation (Li Jun)

   - Fix use-after-free of perf domain in netlink doit handlers for
     energy models (Fan Wu)

   - Add synchronize_rcu() back to cpu_pm_unregister_notifier() after it
     was removed inadvertently in previous development cycles to avoid
     use-after-free (Bradley Morgan)

   - Unregister CPU PM notifier outside the timer lock in the
     timer-ti-dm clocksource driver (Bradley Morgan)

   - Fix typo "sucessfully" in a comment in pm_clk_add_clk() kerneldoc
     comment and typo "hierachy" in a comment in pm-graph (Hemanth
     Selam)

   - Fix the return value in dev_pm_opp_get_of_node() kernel-doc (Karl
     Mehltretter)"

* tag 'pm-7.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (89 commits)
  cpufreq: loongson3: Replace IOCSR read/write with MMIO ones
  cpufreq: loongson3: Use global physical CPU ID in get/target callbacks
  cpufreq: loongson3: Replace per-package mutex with per-node
  cpufreq: loongson3: Adjust the width of id and val in smc_message
  cpufreq: loongson3: Make this driver depend on MACH_LOONGSON64
  PM: runtime: Expand introduction with core concepts and structure
  cpufreq: schedutil: Serialize sugov_start() against rate limit updates
  MAINTAINERS: ACPI: Add a separate CPPC entry
  MAINTAINERS: cpufreq: Replace CPPC reviewer
  arm64: dts: mediatek: mt8173: Mark the lowest CPU OPPs for suspend
  cpufreq: mediatek: Enter system sleep at the suspend OPP
  cpufreq: qcom-cpufreq-hw: fix device node refcount leak in phandle parsing
  cpufreq: qcom-nvmem: Add IPQ9650 support
  cpufreq: Add Milos to cpufreq-dt-platdev blocklist
  cpufreq: Use %pe to print error pointers symbolically
  rust: rcpufreq_dt: add module alias
  cpufreq: sti: avoid NULL dereference in dev_err()
  cpufreq: tegra194: fix double-pointer error in get_cpu_ndiv
  cpufreq: sparc-us2e: fix frequency table index copy-paste error
  rust: cpufreq: reject NULL from cpufreq_cpu_get()
  ...
2026-10-21 14:24:26 -10:00
arch Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
block vfs-7.4-rc1.iomap 2026-10-19 18:33:02 -10:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto lib/crypto: sparc/aes-xts: Add optimization using the AES opcodes 2026-10-04 21:40:47 +02:00
Documentation Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
drivers Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
fs Updates for the core timekeeping and timers subsystem: 2026-10-21 11:20:38 -10:00
include Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
init Kbuild / Kconfig updates for 7.4 2026-10-21 10:45:44 -10:00
io_uring Updates for the core timekeeping and timers subsystem: 2026-10-21 11:20:38 -10:00
ipc vfs-7.4-rc1.idmap 2026-10-19 17:57:49 -10:00
kernel Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
lib Updates for the VDSO subsystem: 2026-10-21 11:33:33 -10:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm \n 2026-10-20 16:30:13 -10:00
net Updates for the core timekeeping and timers subsystem: 2026-10-21 11:20:38 -10:00
rust Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
samples configfs: Updates for v7.4 2026-10-20 16:25:43 -10:00
scripts Kbuild / Kconfig updates for 7.4 2026-10-21 10:45:44 -10:00
security lsm/stable-7.4 PR 20261016 2026-10-20 20:04:07 -10:00
sound ACPI support updates for 7.4-rc1 2026-10-21 12:08:18 -10:00
tools Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
usr Merge branch 'kbuild-next-speedups' into kbuild-next 2026-10-17 15:20:23 -07:00
virt vfs-7.4-rc1.idmap 2026-10-19 17:57:49 -10:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add myself 2026-09-07 10:01:33 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore .gitignore: drop Module.markers 2026-10-04 18:18:08 +02:00
.mailmap Changes since last update: 2026-10-20 16:50:37 -10:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
AGENTS.md docs: add AGENTS.md as a symlink to README 2026-10-14 11:45:46 -06:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS vfs-7.4-rc1.bfs 2026-10-19 16:55:31 -10:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Power management updates for 7.4-rc1 2026-10-21 14:24:26 -10:00
Makefile Kbuild / Kconfig updates for 7.4 2026-10-21 10:45:44 -10:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

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
* AI Coding Assistant: LLMs and AI-powered development tools


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

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


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