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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Pull spi fixes from Mark Brown:
"A couple of changes here, one update to MAINTAINERS for the AMD
controller and a chnage from Pei Xiao which in spite of the changelog
is actually a fix - previously the zynq-qspi driver leaked a clock
enable for every flash operation it did which isn't good, these extra
enables were removed when doing the enable cleanup which are probably
a good idea anyway"
* tag 'spi-fix-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
MAINTAINERS: Update AMD SPI driver maintainers
spi: zynq-qspi: Simplify clock handling with devm_clk_get_enabled()
Pull regulator fix from Mark Brown:
"One last fix for v7.0, the BD72720 incorrectly described which DCDC is
tied to the LDO for its LDON-HEAD mode which automates using the DCDC
to more efficiently drop a supply for delivery via the LDO"
* tag 'regulator-fix-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regulator:
regulator: bd71828-regulator.c: Fix LDON-HEAD mode
Due to additional responsibilities, Raju Rangoju will no longer be
supporting AMD SPI driver. Maintenance will be handled by Krishnamoorthi
going forward.
Cc: Krishnamoorthi M <krishnamoorthi.m@amd.com>
Signed-off-by: Raju Rangoju <Raju.Rangoju@amd.com>
Link: https://patch.msgid.link/20260406091042.4065767-1-Raju.Rangoju@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull kvm fixes from Paolo Bonzini:
"s390:
- vsie: Fix races with partial gmap invalidations
x86:
- Use __DECLARE_FLEX_ARRAY() for UAPI structures with VLAs"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: s390: vsie: Fix races with partial gmap invalidations
KVM: x86: Use __DECLARE_FLEX_ARRAY() for UAPI structures with VLAs
The ROHM BD72720 supports so called LDON-HEAD -mode, in which the buck10
is expected to be supplying power for an LDO. In this mode, the buck10
voltage will follow what is set for the LDO, on order to lower the
power-loss in the LDO.
This hardware configuration can be adverticed via the device-tree. When
this is done, the Linux driver should omit registering the voltage
control operations for the buck10, because the voltage control is now
done by the hardware.
This is done by modifying the buck10 regulator descriptor, before
passing it to the regulator registration functions. There is an
off-by-one error when the regulator descriptor array is indexed, and
wrong descriptor is modified causing the LDO1 operations to be modified
instead of the BUCK10 operations.
Fix this by correcting the indexing.
Signed-off-by: Matti Vaittinen <mazziesaccount@gmail.com>
Fixes: f16a9d76a71d ("regulator: bd71828: Support ROHM BD72720")
Link: https://patch.msgid.link/e7eef0bd407522ae5d9b7d0c4ec43f40b1dba833.1775565148.git.mazziesaccount@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Replace devm_clk_get() followed by clk_prepare_enable() with
devm_clk_get_enabled() for both "pclk" and "ref_clk". This removes
the need for explicit clock enable and disable calls, as the managed
API automatically disables the clocks on device removal or probe
failure.
Remove the now-unnecessary clk_disable_unprepare() calls from the
probe error paths and the remove callback. Simplify error handling
by jumping directly to the remove_ctlr label.
Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Acked-by: Michal Simek <michal.simek@amd.com>
Link: https://patch.msgid.link/24043625f89376da36feca2408f990a85be7ab36.1775555500.git.xiaopei01@kylinos.cn
Signed-off-by: Mark Brown <broonie@kernel.org>
Pull tracing probe fix from Masami Hiramatsu:
"Reject non-closed empty immediate strings
Fix a buffer index underflow bug that occurred when passing an
non-closed empty immediate string to the probe event"
* tag 'probes-fixes-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
tracing/probe: reject non-closed empty immediate strings
KVM: s390: One very last second fix
Fix one more gmap-rewrite issue: races with partial gmap invalidations.
Pull USB fix from Greg KH:
"Here is a single USB fix for a reported regression in a recent USB
typec patch for 7.0-final. Sorry for the late submission, but it does
fix a problem that people have been seeing with 7.0-rc7 and the stable
kernels (due to a backported fix from there.)
This has been in linux-next this week with no reported issues, and the
reporter (Takashi), has said it resolves the problem they were seeing"
* tag 'usb-7.0-final' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
usb: typec: ucsi: skip connector validation before init
parse_probe_arg() accepts quoted immediate strings and passes the body
after the opening quote to __parse_imm_string(). That helper currently
computes strlen(str) and immediately dereferences str[len - 1], which
underflows when the body is empty and not closed with double-quotation.
Reject empty non-closed immediate strings before checking for the closing quote.
Link: https://lore.kernel.org/all/20260401160315.88518-1-pengpeng@iscas.ac.cn/
Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
KVM x86 fixes for 7.1
Declare flexible arrays in uAPI structures using __DECLARE_FLEX_ARRAY() so
that KVM's uAPI headers can be included in C++ projects.
Introduce a new boolean flag, used for shadow gmaps, to keep track of
whether the gmap has been invalidated, either partially or totally.
Use the new flag to check whether shadow gmap invalidations happened
during shadowing. In such cases, abort whatever was going on, return
-EAGAIN and let the caller try again.
Fixes: 19d6c5b80443 ("KVM: s390: vsie: Fix unshadowing while shadowing")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260407161721.247044-1-imbrenda@linux.ibm.com>
Pull RISC-V fixes from Paul Walmsley:
- Fix a CONFIG_SPARSEMEM crash on RV32 by avoiding early phys_to_page()
- Prevent runtime const infrastructure from being used by modules,
similar to what was done for x86
- Avoid problems when shutting down ACPI systems with IOMMUs by adding
a device dependency between IOMMU and devices that use it
- Fix a bug where the CPU pointer masking state isn't properly reset
when tagged addresses aren't enabled for a task
- Fix some incorrect register assignments, and add some missing ones,
in kgdb support code
- Fix compilation of non-kernel code that uses the ptrace uapi header
by replacing BIT() with _BITUL()
- Fix compilation of the validate_v_ptrace kselftest by working around
kselftest macro expansion issues
* tag 'riscv-for-linus-7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
ACPI: RIMT: Add dependency between iommu and devices
selftests: riscv: Add braces around EXPECT_EQ()
riscv: use _BITUL macro rather than BIT() in ptrace uapi and kselftests
riscv: Reset pmm when PR_TAGGED_ADDR_ENABLE is not set
riscv: make runtime const not usable by modules
riscv: patch: Avoid early phys_to_page()
riscv: kgdb: fix several debug register assignment bugs
Pull input fixes from Dmitry Torokhov:
"Two fixes for force feedback handling in uinput driver:
- fix circular locking dependency in uinput
- fix potential corruption of uinput event queue"
* tag 'input-for-v7.0-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
Input: uinput - take event lock when submitting FF request "event"
Input: uinput - fix circular locking dependency with ff-core
Notifications can arrive before ucsi_init() has populated
ucsi->cap.num_connectors via GET_CAPABILITY. At that point
num_connectors is still 0, causing all valid connector numbers to be
incorrectly rejected as bogus.
Skip the bounds check when num_connectors is 0 (not yet initialized).
Pre-init notifications are already handled safely by the early-event
guard in ucsi_connector_change().
Reported-by: Takashi Iwai <tiwai@suse.de>
Fixes: d2d8c17ac01a ("usb: typec: ucsi: validate connector number in ucsi_notify_common()")
Cc: stable@vger.kernel.org
Signed-off-by: Nathan Rebello <nathan.c.rebello@gmail.com>
Tested-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260407063958.863-1-nathan.c.rebello@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>