Linus Torvalds 85cdaca697 Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 updates from Will Deacon:
 "There's a reasonable amount of stuff here, including a bunch of
  updates to the perf PMU drivers and some MPAM updates to expose the
  memory bandwidth counters via resctrl.

  On the architecture side, some highlights include support for BBML3
  and steps towards support for an architectural NMI solution, all
  wrapped up in a web of fixes for latent issues identified by Sashiko.

  ACPI:

   - Combine reads of AMU counters into a single FFH feedback counter op

  Confidential computing:

   - Fix smp_processor_id() in preemptible context when retrieving an
     attestation token inside a realm

   - Convert pKVM over to a "CC platform"

   - Clean-up our SWIOTLB configuration in preparation for reworking the
     handling of encrypted/decryped DMA buffers in the dma-mapping tree

  CPU errata handling:

   - Work around broken device memory ordering on NVIDIA Olympus cores

   - Fix broken 'nospectre_bhb' command-line option

   - Select the idle loop backend instruction on the command-line

  CPU features:

   - Replace our BBML2-noabort feature with the new architectural BBML3
     feature

   - Disable in-kernel BTI for recent versions of Clang due to issues
     with livepatch that are still being investigated

   - Clean-up documentation describing which ID register fields are
     exposed to userspace

  Interrupts:

   - Preliminary work towards supporting FEAT_NMI, which cleans up our
     IRQ entry code and fixes some latent issues with pseudo-NMI

   - Support for an SDEI backend to trigger an NMI backtrace

  Memory management:

   - Treat all devices as coherent when CLIDR_EL1.LoC == 0

   - Fix no-map handling of sub-page-sized regions

   - Second attempt at unmapping the linear aliases of the kernel data
     and bss sections

   - Fix EFI runtime calls when software-PAN is enabled

  Miscellaneous:

   - Add Mark Rutland as a reviewer!

   - Tidy-up our futex cmpxchg logic when using the new LSUI
     instructions

   - Drop the requirement on DYNAMIC_FTRACE_WITH_CALL_OPS when
     selecting HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS

   - Fix a false-positive KCSCAN splat in the delay loop

   - Use a portable typedef for 128-bit scalar types in our UAPI headers

   - Non-critical fixes for Sashiko reports all over

  MPAM:

   - Hook MPAM memory bandwidth counters into resctrl's counter
     assignment interface

   - Fix a quirk in the MPAM bandwidth counting on Nvidia T241 so that
     it also applies to 63 bit counters

  Perf:

   - Workarounds for hardware issues in the CMN-S3 PMU (Graviton 5) and
     CPU PMU (NVIDIA Olympus again!)

   - Add support for the DDR PMU on Marvell CN20K SoCs

   - Add support for Picoheart implementations of the DCW PCIe PMU

   - Add support for Channel/Rank/Bank filtering in the CXL PMU driver

   - Add support for 64-bit counters in the CSPMU device

   - Add support for revision 2 of the CMN S3 PMU

  Ptrace:

   - Fix a decade-old bug in our handling of seccomp and tracing on
     syscall entry

   - Fix regset handling for inactive SVE and SSVE registers

  Selftests

   - Add some tests for the decade-old bug that we just tried to fix in
     our syscall entry path

   - Fix SVE test crash on SME-only CPUs"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (95 commits)
  arm64/efi: Avoid voluntary preemption with efi_mm installed
  arm64: bti: Disable in-kernel BTI with recent versions of Clang
  arm64: entry: Avoid unnecessary local_irq_disable() on kernel exit
  irqchip/gic-v3: make the unmasking of pseudo-NMIs explicit when handling IRQs
  arm64: Disable KCSAN instrumentation in delay.o
  arm_mpam: Disable driver unbind to avoid UAF
  arm_mpam: Fix a NULL pointer dereference on unbinding after an error interrupt
  perf: arm_pmuv3: Zero initialize hw_id branch stack field
  arm64: mm: Unmap kernel data/bss entirely from the linear map
  iommu/arm-smmu-v3-sva: Use system_supports_bbml3() to detect CPU feature
  perf/arm-cmn: Support CMN S3 r2
  perf/arm-cmn: Plumb in new filter types
  perf/arm-cmn: Refactor event filter data
  perf/arm-cmn: Refactor event filter programming
  perf/arm-cmn: Rename filter variables for clarity
  arm64: mm: fix accidental linear mapping of no-map reserved memory
  tools: Ensure tools copy of linux/filter.h exports the UAPI
  kselftest/arm64: Fix abi test compilation errors
  arch: arm64: add early_param idle=<wfi|yield|nop>
  arm64: entry: mask DAIF before returning from C EL1 handlers
  ...
2026-08-18 11:57:17 -07:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2026-07-14 16:34:04 +02:00
2025-02-19 14:53:27 -07:00

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
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