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 arm platform SoC code updates from Arnd Bergmann:
"These are mainly code cleanups, dropping some unneeded code, plus a
reference counting leak fix"
* tag 'soc-arm-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
ARM: at91: remove unnecessary of_platform_default_populate calls
ARM: at91: Move PM init functions to .init_late hook
ARM: omap1: drop unused Kconfig symbol
ARM: omap2: Fix reference count leaks in omap_control_init()
Pull SoC driver updates from Arnd Bergmann:
"There are are a number of to firmware drivers, in particular the TEE
subsystem:
- a bus callback for TEE firmware that device drivers can register to
- sysfs support for tee firmware information
- minor updates to platform specific TEE drivers for AMD, NXP,
Qualcomm and the generic optee driver
- ARM SCMI firmware refactoring to improve the protocol discover
among other fixes and cleanups
- ARM FF-A firmware interoperability improvements
The reset controller and memory controller subsystems gain support for
additional hardware platforms from Mediatek, Renesas, NXP, Canaan and
SpacemiT.
Most of the other changes are for random drivers/soc code. Among a
number of cleanups and newly added hardware support, including:
- Mediatek MT8196 DVFS power management and mailbox support
- Qualcomm SCM firmware and MDT loader refactoring, as part of the
new Glymur platform support.
- NXP i.MX9 System Manager firmware support for accessing the syslog
- Minor updates for TI, Renesas, Samsung, Apple, Marvell and AMD
SoCs"
* tag 'soc-drivers-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (171 commits)
bus: fsl-mc: fix an error handling in fsl_mc_device_add()
reset: spacemit: Add SpacemiT K3 reset driver
reset: spacemit: Extract common K1 reset code
reset: Create subdirectory for SpacemiT drivers
dt-bindings: soc: spacemit: Add K3 reset support and IDs
reset: canaan: k230: drop OF dependency and enable by default
reset: rzg2l-usbphy-ctrl: Add suspend/resume support
reset: rzg2l-usbphy-ctrl: Propagate the return value of regmap_field_update_bits()
reset: gpio: check the return value of gpiod_set_value_cansleep()
reset: imx8mp-audiomix: Support i.MX8ULP SIM LPAV
reset: imx8mp-audiomix: Extend the driver usage
reset: imx8mp-audiomix: Switch to using regmap API
reset: imx8mp-audiomix: Drop unneeded macros
soc: fsl: qe: qe_ports_ic: Consolidate chained IRQ handler install/remove
soc: mediatek: mtk-cmdq: Add mminfra_offset adjustment for DRAM addresses
soc: mediatek: mtk-cmdq: Extend cmdq_pkt_write API for SoCs without subsys ID
soc: mediatek: mtk-cmdq: Add pa_base parsing for hardware without subsys ID support
soc: mediatek: mtk-cmdq: Add cmdq_get_mbox_priv() in cmdq_pkt_create()
mailbox: mtk-cmdq: Add driver data to support for MT8196
mailbox: mtk-cmdq: Add mminfra_offset configuration for DRAM transaction
...
ARM: omap: soc updates for v6.20
* tag 'omap-for-v6.20/soc-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/khilman/linux-omap:
ARM: omap1: drop unused Kconfig symbol
ARM: omap2: Fix reference count leaks in omap_control_init()
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Pull SoC defconfig updates from Arnd Bergmann:
"These are the usual updates, enabling mode newly merged device drivers
for various Arm and RISC-V based platforms in the defconfig files.
The Renesas and NXP defconfig files also get a refresh for modified
Kconfig options"
* tag 'soc-defconfig-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc:
riscv: defconfig: spacemit: k3: enable clock support
ARM: defconfig: turn off CONFIG_EXPERT
ARM: defconfig: move entries
arm64: defconfig: Enable configurations for Kontron SMARC-sAM67
ARM: imx_v4_v5_defconfig: update for v6.19-rc1
arm64: defconfig: Enable Apple Silicon drivers
arm64: select APPLE_PMGR_PWRSTATE for ARCH_APPLE
arm64: defconfig: Enable Mediatek HDMIv2 driver
ARM: shmobile: defconfig: Refresh for v6.19-rc1
arm64: defconfig: Enable PCIe for the Renesas RZ/G3S SoC
arm64: defconfig: Enable RZ/G3E USB3 PHY driver
arm64: defconfig: Enable EC drivers for Qualcomm-based laptops
arm64: defconfig: Enable options for Qualcomm Milos SoC
ARM: imx_v6_v7_defconfig: enable EPD regulator needed for Kobo Clara 2e
ARM: imx_v6_v7_defconfig: Configure CONFIG_SND_SOC_FSL_ASOC_CARD as module
ARM: multi_v7_defconfig: enable DA9052 and MC13XXX
arm64: defconfig: enable clocks, interconnect and pinctrl for Qualcomm Kaanapali
arm64: defconfig: Drop duplicate CONFIG_OMAP_USB2 entry
arm64: defconfig: Enable missing AMD/Xilinx drivers
FSL SOC Changes for 6.20
Freescale Management Complex:
- Convert fsl-mc bus to bus callbacks
- Fix a use-after-free
- Drop redundant error messages
- Fix ressources release on some error path
Freescale QUICC Engine:
- Add an interrupt controller for IO Ports
- Use scoped for-each OF child loop
* tag 'soc_fsl-6.20-1' of https://git.kernel.org/pub/scm/linux/kernel/git/chleroy/linux:
bus: fsl-mc: fix an error handling in fsl_mc_device_add()
soc: fsl: qe: qe_ports_ic: Consolidate chained IRQ handler install/remove
dt-bindings: soc: fsl: qe: Add an interrupt controller for QUICC Engine Ports
soc: fsl: qe: Add an interrupt controller for QUICC Engine Ports
soc: fsl: qe: Simplify with scoped for each OF child loop
bus: fsl-mc: fix use-after-free in driver_override_show()
bus: fsl-mc: Convert to bus callbacks
bus: fsl-mc: Drop error message in probe function
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Microchip AT91 SoC updates for v6.20
This update includes:
- drop the use of of_platform_default_populate() from the
machine specific code, as it is already handled by the DT core
* tag 'at91-soc-6.20' of https://git.kernel.org/pub/scm/linux/kernel/git/at91/linux:
ARM: at91: remove unnecessary of_platform_default_populate calls
ARM: at91: Move PM init functions to .init_late hook
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
"select ARCH_HAS_HOLES_MEMORYMODEL" was mistakenly merged here
due to a botched rebase (says Arnd [1]).
Drop that line since that symbol is not used anywhere else in the
kernel source tree.
[1] https://lore.kernel.org/all/5e335232-89b4-4c35-93bd-efad7e4d8995@app.fastmail.com/
Fixes: 7036440eab3e ("ARM: omap1: enable multiplatform")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Link: https://patch.msgid.link/20251230055230.3212260-1-rdunlap@infradead.org
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Pull asm-generic header updates from Arnd Bergmann:
"A series from Thomas Weißschuh cleans up the UAPI header files to no
longer contain any references to Kconfig symbols, as these make no
sense in userspace.
The build-time check for these was originally added by Sam Ravnborg in
linux-2.6.28, and a later version started warning for all newly added
CONFIG_* checks here but kept a list of known exceptions. With the
last exceptions gone from that list, the warning is now unconditional
in 'make headers_install'.
John Garry contributed a cleanup of cpumask_of_node()"
* tag 'asm-generic-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
scripts: headers_install.sh: Remove config leak ignore machinery
x86/uapi: Stop leaking kconfig references to userspace
nios2: uapi: Remove custom asm/swab.h from UAPI
ARM: uapi: Drop PSR_ENDSTATE
ARC: Always use SWAPE instructions for __arch_swab32()
include/asm-generic/topology.h: Remove unused definition of cpumask_of_node()
MediaTek defconfig updates
This adds a single change, enabling to compile the
MediaTek HDMIv2 driver as module.
* tag 'mtk-defconfig-for-v6.20' of https://git.kernel.org/pub/scm/linux/kernel/git/mediatek/linux:
arm64: defconfig: Enable Mediatek HDMIv2 driver
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Two fixes for the default-settings code for the General-Register-Files,
which sets system defaults for some settings like disabling the automatic
jtag/sdmmc switching.
One is a corrected register-offset and the other makes the code actually
look for all matched GRF instances, which it didn't do before.
* tag 'v6.20-rockchip-drivers1' of https://git.kernel.org/pub/scm/linux/kernel/git/mmind/linux-rockchip:
soc: rockchip: grf: Support multiple grf to be handled
soc: rockchip: grf: Fix wrong RK3576_IOCGRF_MISC_CON definition
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
In fsl_mc_device_add(), device_initialize() is called first.
put_device() should be called to drop the reference if error
occurs. And other resources would be released via put_device
-> fsl_mc_device_release. So remove redundant kfree() in
error handling path.
Fixes: bbf9d17d9875 ("staging: fsl-mc: Freescale Management Complex (fsl-mc) bus driver")
Cc: stable@vger.kernel.org
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/b767348e-d89c-416e-acea-1ebbff3bea20@stanley.mountain/
Signed-off-by: Su Hui <suhui@nfschina.com>
Suggested-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Link: https://lore.kernel.org/r/20260124102054.1613093-1-lihaoxiang@isrc.iscas.ac.cn
Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
The DT core will call of_platform_default_populate, so it is not
necessary for machine specific code to call it unless there are custom
match entries, auxdata or parent device. Neither of those apply here, so
remove the call.
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20260105-at91-probe-v3-3-594013ff2965@kernel.org
Signed-off-by: Claudiu Beznea <claudiu.beznea@tuxon.dev>
The of_get_child_by_name() function increments the reference count
of child nodes, causing multiple reference leaks in omap_control_init():
1. scm_conf node never released in normal/error paths
2. clocks node leak when checking existence
3. Missing scm_conf release before np in error paths
Fix these leaks by adding proper of_node_put() calls and separate error
handling.
Fixes: e5b635742e98 ("ARM: OMAP2+: control: add syscon support for register accesses")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Andreas Kemnade <andreas@kemnade.info>
Link: https://patch.msgid.link/20251217142122.1861292-1-vulab@iscas.ac.cn
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Commit 93d73005bff4 ("x86/entry/vdso: Rename vdso_image_* to
vdso*_image") updated the vdso .gitignore file with the new filenames,
which is certainly not incorrect.
However, while adding new generated names is obviously the right thing
to do, you should *not* immediately remove the old filenames from the
.gitignore file when things move around or get renamed, because people
still have those old generated files in their build trees - and they
haven't suddenly become valid files to commit to the repository just
because they were moved or renamed.
While it's mostly just a slight visual nuisance for 'git status' that
can be fixed up with a clean build tree, it can become more serious than
that: see for example commit 04a3389b3535 ("Remove stale generated
'genheaders' file").
That commit removed up a stale generated file that had been carelessly
committed by a kernel developer because it wasn't properly ignored any
more and thus showed up as a new file in their tree.
Fixes: 93d73005bff4 ("x86/entry/vdso: Rename vdso_image_* to vdso*_image")
Cc: Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are no entries left to ignore and none should be added again.
Remove the now unused logic.
Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>