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 objtool fixes from Ingo Molnar:
- Fix cross-build bug by using HOSTCFLAGS for HAVE_XXHASH test
- Fix klp bug by fixing detection of corrupt static branch/call entries
- Handle unsupported pr_debug() usage more gracefully
- Fix hypothetical klp bug by avoiding NULL pointer dereference when
printing code symbol name
- Fix data alignment bug in elf_add_data() causing mangled strings
- Fix confusing ERROR_INSN() error message
- Handle unexpected Clang RSP musical chairs causing false positive
warnings
- Fix another objtool stack overflow in validate_branch()
* tag 'objtool-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix another stack overflow in validate_branch()
objtool: Handle Clang RSP musical chairs
objtool: Fix ERROR_INSN() error message
objtool: Fix data alignment in elf_add_data()
objtool: Use HOSTCFLAGS for HAVE_XXHASH test
objtool/klp: Avoid NULL pointer dereference when printing code symbol name
objtool/klp: Disable unsupported pr_debug() usage
objtool/klp: Fix detection of corrupt static branch/call entries
Pull irq fixes from Ingo Molnar:
"Two fixes for the riscv-aplic irqchip driver:
- Fix probing dependency bug on probing failure
- Fix double register_syscore() bug"
* tag 'irq-urgent-2026-03-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
irqchip/riscv-aplic: Register syscore operations only once
irqchip/riscv-aplic: Do not clear ACPI dependencies on probe failure
The insn state is getting saved on the stack twice for each recursive
iteration. No need for that, once is enough.
Fixes the following reported stack overflow:
drivers/scsi/qla2xxx/qla_dbg.o: error: SIGSEGV: objtool stack overflow!
Segmentation fault
Fixes: 70589843b36f ("objtool: Add option to trace function validation")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com
Link: https://patch.msgid.link/8b97f62d083457f3b0a29a424275f7957dd3372f.1772821683.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Pull i3c fixes from Alexandre Belloni:
"This introduces the I3C_OR_I2C symbol which is not a fix per se but is
affecting multiple subsystems so it is included to ease
synchronization.
Apart from that, Adrian is mostly fixing the mipi-i3c-hci driver DMA
handling, and I took the opportunity to add two fixes for the dw-i3c
driver.
Subsystem:
- simplify combined i3c/i2c dependencies
Drivers:
- dw: handle 2C properly, fix possible race condition
- mipi-i3c-hci: many DMA related fixes"
* tag 'i3c/fixes-for-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux:
i3c: dw-i3c-master: Set SIR_REJECT in DAT on device attach and reattach
i3c: master: dw-i3c: Fix missing of_node for virtual I2C adapter
i3c: mipi-i3c-hci: Fallback to software reset when bus disable fails
i3c: mipi-i3c-hci: Fix handling of shared IRQs during early initialization
i3c: mipi-i3c-hci: Fix race in DMA error handling in interrupt context
i3c: mipi-i3c-hci: Consolidate common xfer processing logic
i3c: mipi-i3c-hci: Restart DMA ring correctly after dequeue abort
i3c: mipi-i3c-hci: Add missing TID field to no-op command descriptor
i3c: mipi-i3c-hci: Correct RING_CTRL_ABORT handling in DMA dequeue
i3c: mipi-i3c-hci: Fix race between DMA ring dequeue and interrupt handler
i3c: mipi-i3c-hci: Fix race in DMA ring dequeue
i3c: mipi-i3c-hci: Fix race in DMA ring enqueue for parallel xfers
i3c: mipi-i3c-hci: Consolidate spinlocks
i3c: mipi-i3c-hci: Factor out DMA mapping from queuing path
i3c: mipi-i3c-hci: Fix Hot-Join NACK
i3c: mipi-i3c-hci: Use ETIMEDOUT instead of ETIME for timeout errors
i3c: simplify combined i3c/i2c dependencies
Since commit 95a8ddde3660 ("irqchip/riscv-aplic: Preserve APLIC
states across suspend/resume"), when multiple NUMA nodes exist
and AIA is not configured as "none", aplic_probe() is called
multiple times. This leads to register_syscore(&aplic_syscore)
being invoked repeatedly, causing the following Oops:
list_add double add: new=ffffffffb91461f0, prev=ffffffffb91461f0, next=ffffffffb915c408.
[<ffffffffb7b5c8ca>] __list_add_valid_or_report+0x60/0xc0
[<ffffffffb7cc3236>] register_syscore+0x3e/0x70
[<ffffffffb7b8d61c>] aplic_probe+0xc6/0x112
Fix this by registering syscore operations only once, using a static
variable aplic_syscore_registered to track registration.
[ tglx: Trim backtrace properly ]
Fixes: 95a8ddde3660 ("irqchip/riscv-aplic: Preserve APLIC states across suspend/resume")
Signed-off-by: Jessica Liu <liu.xuemei1@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260310141731145xMwLsyvXl9Gw-m6A4VRYj@zte.com.cn
For no apparent reason (possibly related to CONFIG_KMSAN), Clang can
randomly pass the value of RSP to other registers and then back again to
RSP. Handle that accordingly.
Fixes the following warnings:
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: undefined stack state
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: unknown CFA base reg -1
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com
Link: https://patch.msgid.link/240e6a172cc73292499334a3724d02ccb3247fc7.1772818491.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Pull i2c fix from Wolfram Sang:
"Designware DT binding maintainer update"
* tag 'i2c-for-7.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
dt-bindings: i2c: dw: Update maintainer
The DesignWare I3C master controller ACKs IBIs as soon as a valid
Device Address Table (DAT) entry is present. This can create a race
between device attachment (after DAA) and the point where the client
driver enables IBIs via i3c_device_enable_ibi().
Set DEV_ADDR_TABLE_SIR_REJECT in the DAT entry during
attach_i3c_dev() and reattach_i3c_dev() so that IBIs are rejected
by default. The bit is managed thereafter by the existing
dw_i3c_master_set_sir_enabled() function, which clears it in
enable_ibi() after ENEC is issued, and restores it in disable_ibi()
after DISEC.
Fixes: 1dd728f5d4d4 ("i3c: master: Add driver for Synopsys DesignWare IP")
Signed-off-by: Adrian Ng Ho Yin <adrianhoyin.ng@altera.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/53f5b8cbdd8af789ec38b95b02873f32f9182dd6.1770962368.git.adrianhoyin.ng@altera.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
aplic_probe() calls acpi_dev_clear_dependencies() unconditionally at the
end, even when the preceding setup (MSI or direct mode) has failed. This is
incorrect because if the device failed to probe, it should not be
considered as active and should not clear dependencies for other devices
waiting on it.
Fix this by returning immediately when the setup fails, skipping the ACPI
dependency cleanup. Also, explicitly return 0 on success instead of relying
on the value of 'rc' to make the success path clear.
Fixes: 5122e380c23b ("irqchip/riscv-aplic: Add ACPI support")
Signed-off-by: Jessica Liu <liu.xuemei1@zte.com.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260310141600411Fu8H8-GXOOgKISU48Tjgx@zte.com.cn
Confusingly, ERROR_INSN() shows "warning:" instead of "error:". Fix that.
Link: https://patch.msgid.link/c4fe793bb3d23fac2c636b2511059af1158410e2.1772681234.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Pull Rust fixes from Miguel Ojeda:
"Toolchain and infrastructure:
- Remap paths to avoid absolute ones starting with the upcoming Rust
1.95.0 release. This improves build reproducibility, avoids leaking
the exact path and avoids having the same path appear in two forms
The approach here avoids remapping debug information as well, in
order to avoid breaking tools that used the paths to access source
files, which was the previous attempt that needed to be reverted
- Allow 'unused_features' lint for the upcoming Rust 1.96.0 release.
While well-intentioned, we do not benefit much from the new lint
- Emit dependency information into '$(depfile)' directly to avoid a
temporary '.d' file (it was an old approach)
'kernel' crate:
- 'str' module: fix warning under '!CONFIG_BLOCK' by making
'NullTerminatedFormatter' public
- 'cpufreq' module: suppress false positive Clippy warning
'pin-init' crate:
- Remove '#[disable_initialized_field_access]' attribute which was
unsound. This means removing the support for structs with unaligned
fields (through the 'repr(packed)' attribute), for now
And document the load-bearing fact of field accessors (i.e. that
they are required for soundness)
- Replace shadowed return token by 'unsafe'-to-create token in order
to remain sound in the face of the likely upcoming Type Alias Impl
Trait (TAIT) and the next trait solver in upstream Rust"
* tag 'rust-fixes-7.0-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ojeda/linux:
rust: kbuild: allow `unused_features`
rust: cpufreq: suppress clippy::double_parens in Policy doctest
rust: pin-init: replace shadowed return token by `unsafe`-to-create token
rust: pin-init: internal: init: document load-bearing fact of field accessors
rust: pin-init: internal: init: remove `#[disable_initialized_field_access]`
rust: build: remap path to avoid absolute path
rust: kbuild: emit dep-info into $(depfile) directly
rust: str: make NullTerminatedFormatter public
Jarkko does now work for Intel anymore and since I'm currently
maintaining this driver, update my contact information here to make sure
patches get Cc'd to me as well.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reported-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> (internally)
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
The DesignWare I3C master driver creates a virtual I2C adapter to
provide backward compatibility with I2C devices. However, the current
implementation does not associate this virtual adapter with any
Device Tree node.
Propagate the of_node from the I3C master platform device to the
virtual I2C adapter's device structure. This ensures that standard
I2C aliases are correctly resolved and bus numbering remains consistent.
Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260302075645.1492766-1-peteryin.openbmc@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Any data added to a section needs to be aligned in accordance with the
section's sh_addralign value. Particularly strings added to a .str1.8
section. Otherwise you may get some funky strings.
Fixes: dd590d4d57eb ("objtool/klp: Introduce klp diff subcommand for diffing object files")
Link: https://patch.msgid.link/d962fc0ca24fa0825cca8dad71932dccdd9312a9.1772681234.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Pull USB fixes from Greg KH:
"Here is a large chunk of USB driver fixes for 7.0-rc4. Included in
here are:
- usb gadget reverts due to reported issues, and then a follow-on fix
to hopefully resolve the reported overall problem
- xhci driver fixes
- dwc3 driver fixes
- usb core "killable" bulk message api addition to fix a usbtmc
driver bug where userspace could hang the driver for forever
- small USB driver fixes for reported issues
- new usb device quirks
All except the last USB device quirk change have been in linux-next
with no reported issues. That one came in too late, and is 'obviously
correct' :)"
* tag 'usb-7.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (35 commits)
USB: ezcap401 needs USB_QUIRK_NO_BOS to function on 10gbs usb speed
usb: roles: get usb role switch from parent only for usb-b-connector
Revert "tcpm: allow looking for role_sw device in the main node"
usb: gadget: f_ncm: Fix net_device lifecycle with device_move
Revert "usb: gadget: u_ether: add gether_opts for config caching"
Revert "usb: gadget: u_ether: use <linux/hex.h> header file"
Revert "usb: gadget: u_ether: Add auto-cleanup helper for freeing net_device"
Revert "usb: gadget: f_ncm: align net_device lifecycle with bind/unbind"
Revert "usb: legacy: ncm: Fix NPE in gncm_bind"
Revert "usb: gadget: f_ncm: Fix atomic context locking issue"
usb: typec: altmode/displayport: set displayport signaling rate in configure message
usb: dwc3: pci: add support for the Intel Nova Lake -H
usb/core/quirks: Add Huawei ME906S-device to wakeup quirk
usb: gadget: uvc: fix interval_duration calculation
xhci: Fix NULL pointer dereference when reading portli debugfs files
usb: xhci: Prevent interrupt storm on host controller error (HCE)
usb: xhci: Fix memory leak in xhci_disable_slot()
usb: class: cdc-wdm: fix reordering issue in read code path
usb: renesas_usbhs: fix use-after-free in ISR during device removal
usb: cdc-acm: Restore CAP_BRK functionnality to CH343
...