kernel/linux.git/Documentation/admin-guide/kernel-parameters.txt, branch v6.19.11

usb: core: new quirk to handle devices with zero configurations

2026-04-02T11:25:22+00:00

[ Upstream commit 9f6a983cfa22ac662c86e60816d3a357d4b551e9 ] Some USB devices incorrectly report bNumConfigurations as 0 in their device descriptor, which causes the USB core to reject them during enumeration. logs: usb 1-2: device descriptor read/64, error -71 usb 1-2: no configurations usb 1-2: can't read configurations, error -22 However, these devices actually work correctly when treated as having a single configuration. Add a new quirk USB_QUIRK_FORCE_ONE_CONFIG to handle such devices. When this quirk is set, assume the device has 1 configuration instead of failing with -EINVAL. This quirk is applied to the device with VID:PID 5131:2007 which exhibits this behavior. Signed-off-by: Jie Deng Link: https://patch.msgid.link/20260227084931.1527461-1-dengjie03@kylinos.cn Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

Documentation: document liveupdate cmdline parameter

2026-02-03T02:43:56+00:00

liveupdate is used to enable Live Update Orchestrator (LUO) early during boot. Add it to kernel-parameters.txt so users can discover and use it. Link: https://lkml.kernel.org/r/20260130112036.359806-1-me@linux.beauty Signed-off-by: Li Chen Acked-by: Mike Rapoport (Microsoft) Cc: Arnd Bergmann Cc: "Borislav Petkov (AMD)" Cc: Frank van der Linden Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Kees Cook Cc: Li RongQing Cc: Pawan Gupta Cc: Randy Dunlap Cc: Pratyush Yadav Cc: Pasha Tatashin Signed-off-by: Andrew Morton

docs: kernel-parameters: add kfence parameters

2026-01-15T06:16:20+00:00

Add a brief summary for KFENCE's kernel command-line parameters in admin-guide/kernel-parameters. Link: https://lkml.kernel.org/r/20251222150018.1349672-1-elver@google.com Signed-off-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitriy Vyukov Cc: Jonathan Corbet Signed-off-by: Andrew Morton

Merge tag 'memblock-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

2025-12-07T16:56:10+00:00

Pull memblock update from Mike Rapoport: "Introduce a 'check_pages' boot parameter to decouple simple checks for page state on allocation and free from CONFIG_DEBUG_VM. This allows enabling page checking without building kernel with CONFIG_DEBUG_VM or forcing init_on_{alloc, free} or other heavier mechanisms" * tag 'memblock-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock: mm/mm_init: Introduce a boot parameter for check_pages

Merge tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-12-06T22:01:20+00:00

Pull non-MM updates from Andrew Morton: - "panic: sys_info: Refactor and fix a potential issue" (Andy Shevchenko) fixes a build issue and does some cleanup in ib/sys_info.c - "Implement mul_u64_u64_div_u64_roundup()" (David Laight) enhances the 64-bit math code on behalf of a PWM driver and beefs up the test module for these library functions - "scripts/gdb/symbols: make BPF debug info available to GDB" (Ilya Leoshkevich) makes BPF symbol names, sizes, and line numbers available to the GDB debugger - "Enable hung_task and lockup cases to dump system info on demand" (Feng Tang) adds a sysctl which can be used to cause additional info dumping when the hung-task and lockup detectors fire - "lib/base64: add generic encoder/decoder, migrate users" (Kuan-Wei Chiu) adds a general base64 encoder/decoder to lib/ and migrates several users away from their private implementations - "rbree: inline rb_first() and rb_last()" (Eric Dumazet) makes TCP a little faster - "liveupdate: Rework KHO for in-kernel users" (Pasha Tatashin) reworks the KEXEC Handover interfaces in preparation for Live Update Orchestrator (LUO), and possibly for other future clients - "kho: simplify state machine and enable dynamic updates" (Pasha Tatashin) increases the flexibility of KEXEC Handover. Also preparation for LUO - "Live Update Orchestrator" (Pasha Tatashin) is a major new feature targeted at cloud environments. Quoting the cover letter: This series introduces the Live Update Orchestrator, a kernel subsystem designed to facilitate live kernel updates using a kexec-based reboot. This capability is critical for cloud environments, allowing hypervisors to be updated with minimal downtime for running virtual machines. LUO achieves this by preserving the state of selected resources, such as memory, devices and their dependencies, across the kernel transition. As a key feature, this series includes support for preserving memfd file descriptors, which allows critical in-memory data, such as guest RAM or any other large memory region, to be maintained in RAM across the kexec reboot. Mike Rappaport merits a mention here, for his extensive review and testing work. - "kexec: reorganize kexec and kdump sysfs" (Sourabh Jain) moves the kexec and kdump sysfs entries from /sys/kernel/ to /sys/kernel/kexec/ and adds back-compatibility symlinks which can hopefully be removed one day - "kho: fixes for vmalloc restoration" (Mike Rapoport) fixes a BUG which was being hit during KHO restoration of vmalloc() regions * tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (139 commits) calibrate: update header inclusion Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()" vmcoreinfo: track and log recoverable hardware errors kho: fix restoring of contiguous ranges of order-0 pages kho: kho_restore_vmalloc: fix initialization of pages array MAINTAINERS: TPM DEVICE DRIVER: update the W-tag init: replace simple_strtoul with kstrtoul to improve lpj_setup KHO: fix boot failure due to kmemleak access to non-PRESENT pages Documentation/ABI: new kexec and kdump sysfs interface Documentation/ABI: mark old kexec sysfs deprecated kexec: move sysfs entries to /sys/kernel/kexec test_kho: always print restore status kho: free chunks using free_page() instead of kfree() selftests/liveupdate: add kexec test for multiple and empty sessions selftests/liveupdate: add simple kexec-based selftest for LUO selftests/liveupdate: add userspace API selftests docs: add documentation for memfd preservation via LUO mm: memfd_luo: allow preserving memfd liveupdate: luo_file: add private argument to store runtime state mm: shmem: export some functions to internal.h ...

Merge tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core

2025-12-06T05:29:02+00:00

Pull driver core updates from Danilo Krummrich: "Arch Topology: - Move parse_acpi_topology() from arm64 to common code for reuse in RISC-V CPU: - Expose housekeeping CPUs through /sys/devices/system/cpu/housekeeping - Print a newline (or 0x0A) instead of '(null)' reading /sys/devices/system/cpu/nohz_full when nohz_full= is not set debugfs - Remove (broken) 'no-mount' mode - Remove redundant access mode checks in debugfs_get_tree() and debugfs_create_*() functions Devres: - Remove unused devm_free_percpu() helper - Move devm_alloc_percpu() from device.h to devres.h Firmware Loader: - Replace simple_strtol() with kstrtoint() - Do not call cancel_store() when no upload is in progress kernfs: - Increase struct super_block::maxbytes to MAX_LFS_FILESIZE - Fix a missing unwind path in __kernfs_new_node() Misc: - Increase the name size in struct auxiliary_device_id to 40 characters - Replace system_unbound_wq with system_dfl_wq and add WQ_PERCPU to alloc_workqueue() Platform: - Replace ERR_PTR() with IOMEM_ERR_PTR() in platform ioremap functions Rust: - Auxiliary: - Unregister auxiliary device on parent device unbind - Move parent() to impl Device; implement device context aware parent() for Device - Illustrate how to safely obtain a driver's device private data when calling from an auxiliary driver into the parant device driver - DebugFs: - Implement support for binary large objects - Device: - Let probe() return the driver's device private data as pinned initializer, i.e. impl PinInit - Implement safe accessor for a driver's device private data for Device (returned reference can't out-live driver binding and guarantees the correct private data type) - Implement AsBusDevice trait, to be used by class device abstractions to derive the bus device type of the parent device - DMA: - Store raw pointer of allocation as NonNull - Use start_ptr() and start_ptr_mut() to inherit correct mutability of self - FS: - Add file::Offset type alias - I2C: - Add abstractions for I2C device / driver infrastructure - Implement abstractions for manual I2C device registrations - I/O: - Use "kernel vertical" style for imports - Define ResourceSize as resource_size_t - Move ResourceSize to top-level I/O module - Add type alias for phys_addr_t - Implement Rust version of read_poll_timeout_atomic() - PCI: - Use "kernel vertical" style for imports - Move I/O and IRQ infrastructure to separate files - Add support for PCI interrupt vectors - Implement TryInto> for IrqVector<'a> to convert an IrqVector bound to specific pci::Device into an IrqRequest bound to the same pci::Device's parent Device - Leverage pin_init_scope() to get rid of redundant Result in IRQ methods - PinInit: - Add {pin_}init_scope() to execute code before creating an initializer - Platform: - Leverage pin_init_scope() to get rid of redundant Result in IRQ methods - Timekeeping: - Implement abstraction of udelay() - Uaccess: - Implement read_slice_partial() and read_slice_file() for UserSliceReader - Implement write_slice_partial() and write_slice_file() for UserSliceWriter sysfs: - Prepare the constification of struct attribute" * tag 'driver-core-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/driver-core/driver-core: (75 commits) rust: pci: fix build failure when CONFIG_PCI_MSI is disabled debugfs: Fix default access mode config check debugfs: Remove broken no-mount mode debugfs: Remove redundant access mode checks driver core: Check drivers_autoprobe for all added devices driver core: WQ_PERCPU added to alloc_workqueue users driver core: replace use of system_unbound_wq with system_dfl_wq tick/nohz: Expose housekeeping CPUs in sysfs tick/nohz: avoid showing '(null)' if nohz_full= not set sysfs/cpu: Use DEVICE_ATTR_RO for nohz_full attribute kernfs: fix memory leak of kernfs_iattrs in __kernfs_new_node fs/kernfs: raise sb->maxbytes to MAX_LFS_FILESIZE mod_devicetable: Bump auxiliary_device_id name size sysfs: simplify attribute definition macros samples/kobject: constify 'struct foo_attribute' samples/kobject: add is_visible() callback to attribute group sysfs: attribute_group: enable const variants of is_visible() sysfs: introduce __SYSFS_FUNCTION_ALTERNATIVE() sysfs: transparently handle const pointers in ATTRIBUTE_GROUPS() sysfs: attribute_group: allow registration of const attribute ...

Merge tag 'powerpc-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2025-12-06T00:18:21+00:00

Pull powerpc updates from Michael Ellerman: - Restore clearing of MSR[RI] at interrupt/syscall exit on 32-bit - Fix unpaired stwcx on interrupt exit on 32-bit - Fix race condition leading to double list-add in mac_hid_toggle_emumouse() - Fix mprotect on book3s 32-bit - Fix SLB multihit issue during SLB preload with 64-bit hash MMU - Add support for crashkernel CMA reservation - Add die_id and die_cpumask for Power10 & later to expose chip hemispheres - A series of minor fixes and improvements to the hash SLB code Thanks to Antonio Alvarez Feijoo, Ben Collins, Bhaskar Chowdhury, Christophe Leroy, Daniel Thompson, Dave Vasilevsky, Donet Tom, J. Neuschäfer, Kunwu Chan, Long Li, Naresh Kamboju, Nathan Chancellor, Ritesh Harjani (IBM), Shirisha G, Shrikanth Hegde, Sourabh Jain, Srikar Dronamraju, Stephen Rothwell, Thomas Zimmermann, Venkat Rao Bagalkote, and Vishal Chourasia. * tag 'powerpc-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (32 commits) macintosh/via-pmu-backlight: Include and powerpc/powermac: backlight: Include powerpc/64s/slb: Add no_slb_preload early cmdline param powerpc/64s/slb: Make preload_add return type as void powerpc/ptdump: Dump PXX level info for kernel_page_tables powerpc/64s/pgtable: Enable directMap counters in meminfo for Hash powerpc/64s/hash: Update directMap page counters for Hash powerpc/64s/hash: Hash hpt_order should be only available with Hash MMU powerpc/64s/hash: Improve hash mmu printk messages powerpc/64s/hash: Fix phys_addr_t printf format in htab_initialize() powerpc/64s/ptdump: Fix kernel_hash_pagetable dump for ISA v3.00 HPTE format powerpc/64s/hash: Restrict stress_hpt_struct memblock region to within RMA limit powerpc/64s/slb: Fix SLB multihit issue during SLB preload powerpc, mm: Fix mprotect on book3s 32-bit powerpc/smp: Expose die_id and die_cpumask powerpc/83xx: Add a null pointer check to mcu_gpiochip_add arch:powerpc:tools This file was missing shebang line, so added it kexec: Include kernel-end even without crashkernel powerpc: p2020: Rename wdt@ nodes to watchdog@ powerpc: 86xx: Rename wdt@ nodes to watchdog@ ...

mm/mm_init: Introduce a boot parameter for check_pages

2025-12-04T17:40:25+00:00

Use-after-free and double-free bugs can be very difficult to track down. The kernel is good at tracking these and preventing bad pages from being used/created through simple checks gated behind "check_pages_enabled". Currently, the only ways to enable this flag is by building with CONFIG_DEBUG_VM, or as a side effect of other checks such as init_on_{alloc, free}, page_poisoning, or debug_pagealloc among others. These solutions are powerful, but may often be too coarse in balancing the performance vs. safety that a user may want, particularly in latency-sensitive production environments. Introduce a new boot parameter "check_pages", which enables page checking with no other side effects. It takes kstrbool-able inputs as an argument (i.e. 0/1, true/false, on/off, ...). This patch is backwards-compatible; setting CONFIG_DEBUG_VM still enables page checking. Acked-by: SeongJae Park Acked-by: Michal Hocko Acked-by: Vlastimil Babka Reviewed-by: Anshuman Khandual Signed-off-by: Joshua Hahn Link: https://patch.msgid.link/20251201180739.2330474-1-joshua.hahnjy@gmail.com Signed-off-by: Mike Rapoport (Microsoft)

Merge tag 'docs-6.19' of git://git.lwn.net/linux

2025-12-03T19:34:28+00:00

Pull documentation updates from Jonathan Corbet: "This has been another busy cycle for documentation, with a lot of build-system thrashing. That work should slow down from here on out. - The various scripts and tools for documentation were spread out in several directories; now they are (almost) all coalesced under tools/docs/. The holdout is the kernel-doc script, which cannot be easily moved without some further thought. - As the amount of Python code increases, we are accumulating modules that are imported by multiple programs. These modules have been pulled together under tools/lib/python/ -- at least, for documentation-related programs. There is other Python code in the tree that might eventually want to move toward this organization. - The Perl kernel-doc.pl script has been removed. It is no longer used by default, and nobody has missed it, least of all anybody who actually had to look at it. - The docs build was controlled by a complex mess of makefilese that few dared to touch. Mauro has moved that logic into a new program (tools/docs/sphinx-build-wrapper) that, with any luck at all, will be far easier to understand and maintain. - The get_feat.pl program, used to access information under Documentation/features/, has been rewritten in Python, bringing an end to the use of Perl in the docs subsystem. - The top-level README file has been reorganized into a more reader-friendly presentation. - A lot of Chinese translation additions - Typo fixes and documentation updates as usual" * tag 'docs-6.19' of git://git.lwn.net/linux: (164 commits) docs: makefile: move rustdoc check to the build wrapper README: restructure with role-based documentation and guidelines docs: kdoc: various fixes for grammar, spelling, punctuation docs: kdoc_parser: use '@' for Excess enum value docs: submitting-patches: Clarify that removal of Acks needs explanation too docs: kdoc_parser: add data/function attributes to ignore docs: MAINTAINERS: update Mauro's files/paths docs/zh_CN: Add wd719x.rst translation docs/zh_CN: Add libsas.rst translation get_feat.pl: remove it, as it got replaced by get_feat.py Documentation/sphinx/kernel_feat.py: use class directly tools/docs/get_feat.py: convert get_feat.pl to Python Documentation/admin-guide: fix typo and comment in cscope example docs/zh_CN: Add data-integrity.rst translation docs/zh_CN: Add blk-mq.rst translation docs/zh_CN: Add block/index.rst translation docs/zh_CN: Update the Chinese translation of kbuild.rst docs: bring some order to our Python module hierarchy docs: Move the python libraries to tools/lib/python Documentation/kernel-parameters: Move the kernel build options ...

Merge tag 'pm-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

2025-12-03T01:31:22+00:00

Pull power management updates from Rafael Wysocki: "There are quite a few interesting things here, including new hardware support, new features, some bug fixes and documentation updates. In addition, there are a usual bunch of minor fixes and cleanups all over. In the new hardware support category, there are intel_pstate and intel_rapl driver updates to support new processors, Panther Lake, Wildcat Lake, Noval Lake, and Diamond Rapids in the OOB mode, OPP and bandwidth allocation support in the tegra186 cpufreq driver, and JH7110S SOC support in dt-platdev cpufreq. The new features are the PM QoS CPU latency limit for suspend-to-idle, the netlink support for the energy model management, support for terminating system suspend via a wakeup event during the sync of file systems, configurable number of hibernation compression threads, the runtime PM auto-cleanup macros, and the "poweroff" PM event that is expected to be used during system shutdown. Bugs are mostly fixed in cpuidle governors, but there are also fixes elsewhere, like in the amd-pstate cpufreq driver. Documentation updates include, but are not limited to, a new doc on debugging shutdown hangs, cross-referencing fixes and cleanups in the intel_pstate documentation, and updates of comments in the core hibernation code. Specifics: - Introduce and document a QoS limit on CPU exit latency during wakeup from suspend-to-idle (Ulf Hansson) - Add support for building libcpupower statically (Zuo An) - Add support for sending netlink notifications to user space on energy model updates (Changwoo Mini, Peng Fan) - Minor improvements to the Rust OPP interface (Tamir Duberstein) - Fixes to scope-based pointers in the OPP library (Viresh Kumar) - Use residency threshold in polling state override decisions in the menu cpuidle governor (Aboorva Devarajan) - Add sanity check for exit latency and target residency in the cpufreq core (Rafael Wysocki) - Use this_cpu_ptr() where possible in the teo governor (Christian Loehle) - Rework the handling of tick wakeups in the teo cpuidle governor to increase the likelihood of stopping the scheduler tick in the cases when tick wakeups can be counted as non-timer ones (Rafael Wysocki) - Fix a reverse condition in the teo cpuidle governor and drop a misguided target residency check from it (Rafael Wysocki) - Clean up multiple minor defects in the teo cpuidle governor (Rafael Wysocki) - Update header inclusion to make it follow the Include What You Use principle (Andy Shevchenko) - Enable MSR-based RAPL PMU support in the intel_rapl power capping driver and arrange for using it on the Panther Lake and Wildcat Lake processors (Kuppuswamy Sathyanarayanan) - Add support for Nova Lake and Wildcat Lake processors to the intel_rapl power capping driver (Kaushlendra Kumar, Srinivas Pandruvada) - Add OPP and bandwidth support for Tegra186 (Aaron Kling) - Optimizations for parameter array handling in the amd-pstate cpufreq driver (Mario Limonciello) - Fix for mode changes with offline CPUs in the amd-pstate cpufreq driver (Gautham Shenoy) - Preserve freq_table_sorted across suspend/hibernate in the cpufreq core (Zihuan Zhang) - Adjust energy model rules for Intel hybrid platforms in the intel_pstate cpufreq driver and improve printing of debug messages in it (Rafael Wysocki) - Replace deprecated strcpy() in cpufreq_unregister_governor() (Thorsten Blum) - Fix duplicate hyperlink target errors in the intel_pstate cpufreq driver documentation and use :ref: directive for internal linking in it (Swaraj Gaikwad, Bagas Sanjaya) - Add Diamond Rapids OOB mode support to the intel_pstate cpufreq driver (Kuppuswamy Sathyanarayanan) - Use mutex guard for driver locking in the intel_pstate driver and eliminate some code duplication from it (Rafael Wysocki) - Replace udelay() with usleep_range() in ACPI cpufreq (Kaushlendra Kumar) - Minor improvements to various cpufreq drivers (Christian Marangi, Hal Feng, Jie Zhan, Marco Crivellari, Miaoqian Lin, and Shuhao Fu) - Replace snprintf() with scnprintf() in show_trace_dev_match() (Kaushlendra Kumar) - Fix memory allocation error handling in pm_vt_switch_required() (Malaya Kumar Rout) - Introduce CALL_PM_OP() macro and use it to simplify code in generic PM operations (Kaushlendra Kumar) - Add module param to backtrace all CPUs in the device power management watchdog (Sergey Senozhatsky) - Rework message printing in swsusp_save() (Rafael Wysocki) - Make it possible to change the number of hibernation compression threads (Xueqin Luo) - Clarify that only cgroup1 freezer uses PM freezer (Tejun Heo) - Add document on debugging shutdown hangs to PM documentation and correct a mistaken configuration option in it (Mario Limonciello) - Shut down wakeup source timer before removing the wakeup source from the list (Kaushlendra Kumar, Rafael Wysocki) - Introduce new PMSG_POWEROFF event for system shutdown handling with the help of PM device callbacks (Mario Limonciello) - Make pm_test delay interruptible by wakeup events (Riwen Lu) - Clean up kernel-doc comment style usage in the core hibernation code and remove unuseful comments from it (Sunday Adelodun, Rafael Wysocki) - Add support for handling wakeup events and aborting the suspend process while it is syncing file systems (Samuel Wu, Rafael Wysocki) - Add WQ_UNBOUND to pm_wq workqueue (Marco Crivellari) - Add runtime PM wrapper macros for ACQUIRE()/ACQUIRE_ERR() and use them in the PCI core and the ACPI TAD driver (Rafael Wysocki) - Improve runtime PM in the ACPI TAD driver (Rafael Wysocki) - Update pm_runtime_allow/forbid() documentation (Rafael Wysocki) - Fix typos in runtime.c comments (Malaya Kumar Rout) - Move governor.h from devfreq under include/linux/ and rename to devfreq-governor.h to allow devfreq governor definitions in out of drivers/devfreq/ (Dmitry Baryshkov) - Use min() to improve readability in tegra30-devfreq.c (Thorsten Blum) - Fix potential use-after-free issue of OPP handling in hisi_uncore_freq.c (Pengjie Zhang) - Fix typo in DFSO_DOWNDIFFERENTIAL macro name in governor_simpleondemand.c in devfreq (Riwen Lu)" * tag 'pm-6.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (96 commits) PM / devfreq: Fix typo in DFSO_DOWNDIFFERENTIAL macro name cpuidle: Warn instead of bailing out if target residency check fails cpuidle: Update header inclusion Documentation: power/cpuidle: Document the CPU system wakeup latency QoS cpuidle: Respect the CPU system wakeup QoS limit for cpuidle sched: idle: Respect the CPU system wakeup QoS limit for s2idle pmdomain: Respect the CPU system wakeup QoS limit for cpuidle pmdomain: Respect the CPU system wakeup QoS limit for s2idle PM: QoS: Introduce a CPU system wakeup QoS limit cpuidle: governors: teo: Add missing space to the description PM: hibernate: Extra cleanup of comments in swap handling code PM / devfreq: tegra30: use min to simplify actmon_cpu_to_emc_rate PM / devfreq: hisi: Fix potential UAF in OPP handling PM / devfreq: Move governor.h to a public header location powercap: intel_rapl: Enable MSR-based RAPL PMU support powercap: intel_rapl: Prepare read_raw() interface for atomic-context callers cpufreq: qcom-nvmem: fix compilation warning for qcom_cpufreq_ipq806x_match_list PM: sleep: Call pm_sleep_fs_sync() instead of ksys_sync_helper() PM: sleep: Add support for wakeup during filesystem sync cpufreq: ACPI: Replace udelay() with usleep_range() ...