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Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 347 |
1 files changed, 258 insertions, 89 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 858b6c0b9a15..a5f4004e8705 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -13,7 +13,7 @@ For ARM64, ONLY "acpi=off", "acpi=on" or "acpi=force" are available - See also Documentation/power/runtime_pm.txt, pci=noacpi + See also Documentation/power/runtime_pm.rst, pci=noacpi acpi_apic_instance= [ACPI, IOAPIC] Format: <int> @@ -53,7 +53,7 @@ ACPI_DEBUG_PRINT statements, e.g., ACPI_DEBUG_PRINT((ACPI_DB_INFO, ... The debug_level mask defaults to "info". See - Documentation/acpi/debug.txt for more information about + Documentation/firmware-guide/acpi/debug.rst for more information about debug layers and levels. Enable processor driver info messages: @@ -223,7 +223,7 @@ acpi_sleep= [HW,ACPI] Sleep options Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig, old_ordering, nonvs, sci_force_enable, nobl } - See Documentation/power/video.txt for information on + See Documentation/power/video.rst for information on s3_bios and s3_mode. s3_beep is for debugging; it makes the PC's speaker beep as soon as the kernel's real-mode entry point is called. @@ -430,7 +430,7 @@ blkdevparts= Manual partition parsing of block device(s) for embedded devices based on command line input. - See Documentation/block/cmdline-partition.txt + See Documentation/block/cmdline-partition.rst boot_delay= Milliseconds to delay each printk during boot. Values larger than 10 seconds (10000) are changed to @@ -461,6 +461,11 @@ possible to determine what the correct size should be. This option provides an override for these situations. + carrier_timeout= + [NET] Specifies amount of time (in seconds) that + the kernel should wait for a network carrier. By default + it waits 120 seconds. + ca_keys= [KEYS] This parameter identifies a specific key(s) on the system trusted keyring to be used for certificate trust validation. @@ -473,7 +478,7 @@ others). ccw_timeout_log [S390] - See Documentation/s390/CommonIO for details. + See Documentation/s390/common_io.rst for details. cgroup_disable= [KNL] Disable a particular controller Format: {name of the controller(s) to disable} @@ -511,7 +516,7 @@ /selinux/checkreqprot. cio_ignore= [S390] - See Documentation/s390/CommonIO for details. + See Documentation/s390/common_io.rst for details. clk_ignore_unused [CLK] Prevents the clock framework from automatically gating @@ -699,15 +704,18 @@ upon panic. This parameter reserves the physical memory region [offset, offset + size] for that kernel image. If '@offset' is omitted, then a suitable offset - is selected automatically. Check - Documentation/kdump/kdump.txt for further details. + is selected automatically. + [KNL, x86_64] select a region under 4G first, and + fall back to reserve region above 4G when '@offset' + hasn't been specified. + See Documentation/admin-guide/kdump/kdump.rst for further details. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory in the running system. The syntax of range is start-[end] where start and end are both a memory unit (amount[KMG]). See also - Documentation/kdump/kdump.txt for an example. + Documentation/admin-guide/kdump/kdump.rst for an example. crashkernel=size[KMG],high [KNL, x86_64] range could be above 4G. Allow kernel @@ -797,12 +805,10 @@ tracking down these problems. debug_pagealloc= - [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this - parameter enables the feature at boot time. In - default, it is disabled. We can avoid allocating huge - chunk of memory for debug pagealloc if we don't enable - it at boot time and the system will work mostly same - with the kernel built without CONFIG_DEBUG_PAGEALLOC. + [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this parameter + enables the feature at boot time. By default, it is + disabled and the system will work mostly the same as a + kernel built without CONFIG_DEBUG_PAGEALLOC. on: enable the feature debugpat [X86] Enable PAT debugging @@ -910,6 +916,10 @@ The filter can be disabled or changed to another driver later using sysfs. + driver_async_probe= [KNL] + List of driver names to be probed asynchronously. + Format: <driver_name1>,<driver_name2>... + drm.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>] Broken monitors, graphic adapters, KVMs and EDIDless panels may send no or incorrect EDID data sets. @@ -920,7 +930,7 @@ edid/1680x1050.bin, or edid/1920x1080.bin is given and no file with the same name exists. Details and instructions how to build your own EDID data are - available in Documentation/EDID/HOWTO.txt. An EDID + available in Documentation/driver-api/edid.rst. An EDID data set will only be used for a particular connector, if its name and a colon are prepended to the EDID name. Each connector may use a unique EDID data @@ -951,7 +961,7 @@ for details. nompx [X86] Disables Intel Memory Protection Extensions. - See Documentation/x86/intel_mpx.txt for more + See Documentation/x86/intel_mpx.rst for more information about the feature. nopku [X86] Disable Memory Protection Keys CPU feature found @@ -1073,9 +1083,15 @@ specified address. The serial port must already be setup and configured. Options are not yet supported. + efifb,[options] + Start an early, unaccelerated console on the EFI + memory mapped framebuffer (if available). On cache + coherent non-x86 systems that use system memory for + the framebuffer, pass the 'ram' option so that it is + mapped with the correct attributes. + earlyprintk= [X86,SH,ARM,M68k,S390] earlyprintk=vga - earlyprintk=efi earlyprintk=sclp earlyprintk=xen earlyprintk=serial[,ttySn[,baudrate]] @@ -1171,7 +1187,7 @@ that is to be dynamically loaded by Linux. If there are multiple variables with the same name but with different vendor GUIDs, all of them will be loaded. See - Documentation/acpi/ssdt-overlays.txt for details. + Documentation/admin-guide/acpi/ssdt-overlays.rst for details. eisa_irq_edge= [PARISC,HW] @@ -1182,15 +1198,16 @@ arch/x86/kernel/cpu/cpufreq/elanfreq.c. elevator= [IOSCHED] - Format: {"cfq" | "deadline" | "noop"} - See Documentation/block/cfq-iosched.txt and - Documentation/block/deadline-iosched.txt for details. + Format: { "mq-deadline" | "kyber" | "bfq" } + See Documentation/block/deadline-iosched.rst, + Documentation/block/kyber-iosched.rst and + Documentation/block/bfq-iosched.rst for details. elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390] Specifies physical address of start of kernel core image elf header and optionally the size. Generally kexec loader will pass this option to capture kernel. - See Documentation/kdump/kdump.txt for details. + See Documentation/admin-guide/kdump/kdump.rst for details. enable_mtrr_cleanup [X86] The kernel tries to adjust MTRR layout from continuous @@ -1232,7 +1249,7 @@ See also Documentation/fault-injection/. floppy= [HW] - See Documentation/blockdev/floppy.txt. + See Documentation/admin-guide/blockdev/floppy.rst. force_pal_cache_flush [IA-64] Avoid check_sal_cache_flush which may hang on @@ -1369,9 +1386,6 @@ Valid parameters: "on", "off" Default: "on" - hisax= [HW,ISDN] - See Documentation/isdn/README.HiSax. - hlt [BUGS=ARM,SH] hpet= [X86-32,HPET] option to control HPET usage @@ -1488,7 +1502,7 @@ Format: =0.0 to prevent dma on hda, =0.1 hdb =1.0 hdc .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr .cdrom .chs .ignore_cable are additional options - See Documentation/ide/ide.txt. + See Documentation/ide/ide.rst. ide-generic.probe-mask= [HW] (E)IDE subsystem Format: <int> @@ -1569,7 +1583,7 @@ Format: { "off" | "enforce" | "fix" | "log" } default: "enforce" - ima_appraise_tcb [IMA] + ima_appraise_tcb [IMA] Deprecated. Use ima_policy= instead. The builtin appraise policy appraises all files owned by uid=0. @@ -1596,8 +1610,7 @@ uid=0. The "appraise_tcb" policy appraises the integrity of - all files owned by root. (This is the equivalent - of ima_appraise_tcb.) + all files owned by root. The "secure_boot" policy appraises the integrity of files (eg. kexec kernel image, kernel modules, @@ -1655,6 +1668,15 @@ initrd= [BOOT] Specify the location of the initial ramdisk + init_on_alloc= [MM] Fill newly allocated pages and heap objects with + zeroes. + Format: 0 | 1 + Default set by CONFIG_INIT_ON_ALLOC_DEFAULT_ON. + + init_on_free= [MM] Fill freed pages and heap objects with zeroes. + Format: 0 | 1 + Default set by CONFIG_INIT_ON_FREE_DEFAULT_ON. + init_pkru= [x86] Specify the default memory protection keys rights register contents for all processes. 0x55555554 by default (disallow access to all but pkey 0). Can @@ -1812,6 +1834,9 @@ ip= [IP_PNP] See Documentation/filesystems/nfs/nfsroot.txt. + ipcmni_extend [KNL] Extend the maximum number of unique System V + IPC identifiers from 32,768 to 16,777,216. + irqaffinity= [SMP] Set the default irq affinity mask The argument is a cpu list, as described above. @@ -1830,6 +1855,11 @@ to let secondary kernels in charge of setting up LPIs. + irqchip.gicv3_pseudo_nmi= [ARM64] + Enables support for pseudo-NMIs in the kernel. This + requires the kernel to be built with + CONFIG_ARM64_PSEUDO_NMI. + irqfixup [HW] When an interrupt is not handled search all handlers for it. Intended to get systems with badly broken @@ -1981,6 +2011,12 @@ Built with CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=y, the default is off. + kpti= [ARM64] Control page table isolation of user + and kernel address spaces. + Default: enabled on cores which need mitigation. + 0: force disabled + 1: force enabled + kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs. Default is 0 (don't ignore, but inject #GP) @@ -2114,7 +2150,7 @@ Default is 'flush'. - For details see: Documentation/admin-guide/l1tf.rst + For details see: Documentation/admin-guide/hw-vuln/l1tf.rst l2cr= [PPC] @@ -2198,7 +2234,7 @@ memblock=debug [KNL] Enable memblock debug messages. load_ramdisk= [RAM] List of ramdisks to load from floppy - See Documentation/blockdev/ramdisk.txt. + See Documentation/admin-guide/blockdev/ramdisk.rst. lockd.nlm_grace_period=P [NFS] Assign grace period. Format: <integer> @@ -2318,6 +2354,10 @@ lsm.debug [SECURITY] Enable LSM initialization debugging output. + lsm=lsm1,...,lsmN + [SECURITY] Choose order of LSM initialization. This + overrides CONFIG_LSM, and the "security=" parameter. + machvec= [IA-64] Force the use of a particular machine-vector (machvec) in a generic kernel. Example: machvec=hpzx1_swiotlb @@ -2347,7 +2387,7 @@ mce [X86-32] Machine Check Exception - mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt + mce=option [X86-64] See Documentation/x86/x86_64/boot-options.rst md= [HW] RAID subsystems devices and level See Documentation/admin-guide/md.rst. @@ -2356,6 +2396,32 @@ Format: <first>,<last> Specifies range of consoles to be captured by the MDA. + mds= [X86,INTEL] + Control mitigation for the Micro-architectural Data + Sampling (MDS) vulnerability. + + Certain CPUs are vulnerable to an exploit against CPU + internal buffers which can forward information to a + disclosure gadget under certain conditions. + + In vulnerable processors, the speculatively + forwarded data can be used in a cache side channel + attack, to access data to which the attacker does + not have direct access. + + This parameter controls the MDS mitigation. The + options are: + + full - Enable MDS mitigation on vulnerable CPUs + full,nosmt - Enable MDS mitigation and disable + SMT on vulnerable CPUs + off - Unconditionally disable MDS mitigation + + Not specifying this option is equivalent to + mds=full. + + For details see: Documentation/admin-guide/hw-vuln/mds.rst + mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory Amount of memory to be used when the kernel is not able to see the whole system memory or for test. @@ -2377,7 +2443,7 @@ set according to the CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config option. - See Documentation/memory-hotplug.txt. + See Documentation/admin-guide/mm/memory-hotplug.rst. memmap=exactmap [KNL,X86] Enable setting of an exact E820 memory map, as specified by the user. @@ -2466,7 +2532,7 @@ mem_encrypt=on: Activate SME mem_encrypt=off: Do not activate SME - Refer to Documentation/x86/amd-memory-encryption.txt + Refer to Documentation/virtual/kvm/amd-memory-encryption.rst for details on when memory encryption can be activated. mem_sleep_default= [SUSPEND] Default system suspend mode: @@ -2513,6 +2579,42 @@ in the "bleeding edge" mini2440 support kernel at http://repo.or.cz/w/linux-2.6/mini2440.git + mitigations= + [X86,PPC,S390,ARM64] Control optional mitigations for + CPU vulnerabilities. This is a set of curated, + arch-independent options, each of which is an + aggregation of existing arch-specific options. + + off + Disable all optional CPU mitigations. This + improves system performance, but it may also + expose users to several CPU vulnerabilities. + Equivalent to: nopti [X86,PPC] + kpti=0 [ARM64] + nospectre_v1 [PPC] + nobp=0 [S390] + nospectre_v2 [X86,PPC,S390,ARM64] + spectre_v2_user=off [X86] + spec_store_bypass_disable=off [X86,PPC] + ssbd=force-off [ARM64] + l1tf=off [X86] + mds=off [X86] + + auto (default) + Mitigate all CPU vulnerabilities, but leave SMT + enabled, even if it's vulnerable. This is for + users who don't want to be surprised by SMT + getting disabled across kernel upgrades, or who + have other ways of avoiding SMT-based attacks. + Equivalent to: (default behavior) + + auto,nosmt + Mitigate all CPU vulnerabilities, disabling SMT + if needed. This is for users who always want to + be fully mitigated, even if it means losing SMT. + Equivalent to: l1tf=flush,nosmt [X86] + mds=full,nosmt [X86] + mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this parameter allows control of the logging verbosity for @@ -2738,8 +2840,9 @@ 0 - turn hardlockup detector in nmi_watchdog off 1 - turn hardlockup detector in nmi_watchdog on When panic is specified, panic when an NMI watchdog - timeout occurs (or 'nopanic' to override the opposite - default). To disable both hard and soft lockup detectors, + timeout occurs (or 'nopanic' to not panic on an NMI + watchdog, if CONFIG_BOOTPARAM_HARDLOCKUP_PANIC is set) + To disable both hard and soft lockup detectors, please see 'nowatchdog'. This is useful when you use a panic=... timeout and need the box quickly up again. @@ -2774,6 +2877,17 @@ /sys/module/printk/parameters/console_suspend) to turn on/off it dynamically. + novmcoredd [KNL,KDUMP] + Disable device dump. Device dump allows drivers to + append dump data to vmcore so you can collect driver + specified debug info. Drivers can append the data + without any limit and this data is stored in memory, + so this may cause significant memory stress. Disabling + device dump can help save memory but the driver debug + data will be no longer available. This parameter + is only available when CONFIG_PROC_VMCORE_DEVICE_DUMP + is set. + noaliencache [MM, NUMA, SLAB] Disables the allocation of alien caches in the slab allocator. Saves per-node memory, but will impact performance. @@ -2808,11 +2922,11 @@ noexec=on: enable non-executable mappings (default) noexec=off: disable non-executable mappings - nosmap [X86] + nosmap [X86,PPC] Disable SMAP (Supervisor Mode Access Prevention) even if it is supported by processor. - nosmep [X86] + nosmep [X86,PPC] Disable SMEP (Supervisor Mode Execution Prevention) even if it is supported by processor. @@ -2829,7 +2943,7 @@ register save and restore. The kernel will only save legacy floating-point registers on task switch. - nohugeiomap [KNL,x86] Disable kernel huge I/O mappings. + nohugeiomap [KNL,x86,PPC] Disable kernel huge I/O mappings. nosmt [KNL,S390] Disable symmetric multithreading (SMT). Equivalent to smt=1. @@ -2842,10 +2956,10 @@ check bypass). With this option data leaks are possible in the system. - nospectre_v2 [X86,PPC_FSL_BOOK3E] Disable all mitigations for the Spectre variant 2 - (indirect branch prediction) vulnerability. System may - allow data leaks with this option, which is equivalent - to spectre_v2=off. + nospectre_v2 [X86,PPC_FSL_BOOK3E,ARM64] Disable all mitigations for + the Spectre variant 2 (indirect branch prediction) + vulnerability. System may allow data leaks with this + option. nospec_store_bypass_disable [HW] Disable all mitigations for the Speculative Store Bypass vulnerability @@ -3041,7 +3155,7 @@ numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA. 'node', 'default' can be specified This can be set from sysctl after boot. - See Documentation/sysctl/vm.txt for details. + See Documentation/admin-guide/sysctl/vm.rst for details. ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. See Documentation/debugging-via-ohci1394.txt for more @@ -3079,6 +3193,16 @@ This will also cause panics on machine check exceptions. Useful together with panic=30 to trigger a reboot. + page_alloc.shuffle= + [KNL] Boolean flag to control whether the page allocator + should randomize its free lists. The randomization may + be automatically enabled if the kernel detects it is + running on a platform with a direct-mapped memory-side + cache, and this parameter can be used to + override/disable that behavior. The state of the flag + can be read from sysfs at: + /sys/module/page_alloc/parameters/shuffle. + page_owner= [KNL] Boot-time page_owner enabling option. Storage of the information about who allocated each page is disabled in default. With this switch, @@ -3104,6 +3228,7 @@ bit 2: print timer info bit 3: print locks info if CONFIG_LOCKDEP is on bit 4: print ftrace buffer + bit 5: print all printk messages in buffer panic_on_warn panic() instead of WARN(). Useful to cause kdump on a WARN(). @@ -3154,7 +3279,7 @@ pcd. [PARIDE] See header of drivers/block/paride/pcd.c. - See also Documentation/blockdev/paride.txt. + See also Documentation/admin-guide/blockdev/paride.rst. pci=option[,option...] [PCI] various PCI subsystem options. @@ -3363,6 +3488,8 @@ bridges without forcing it upstream. Note: this removes isolation between devices and may put more devices in an IOMMU group. + force_floating [S390] Force usage of floating interrupts. + nomio [S390] Do not use MIO instructions. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. @@ -3396,7 +3523,7 @@ needed on a platform with proper driver support. pd. [PARIDE] - See Documentation/blockdev/paride.txt. + See Documentation/admin-guide/blockdev/paride.rst. pdcchassis= [PARISC,HW] Disable/Enable PDC Chassis Status codes at boot time. @@ -3411,13 +3538,13 @@ and performance comparison. pf. [PARIDE] - See Documentation/blockdev/paride.txt. + See Documentation/admin-guide/blockdev/paride.rst. pg. [PARIDE] - See Documentation/blockdev/paride.txt. + See Documentation/admin-guide/blockdev/paride.rst. pirq= [SMP,APIC] Manual mp-table setup - See Documentation/x86/i386/IO-APIC.txt. + See Documentation/x86/i386/IO-APIC.rst. plip= [PPT,NET] Parallel port network link Format: { parport<nr> | timid | 0 } @@ -3526,7 +3653,7 @@ prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk before loading. - See Documentation/blockdev/ramdisk.txt. + See Documentation/admin-guide/blockdev/ramdisk.rst. psi= [KNL] Enable or disable pressure stall information tracking. @@ -3548,7 +3675,7 @@ pstore.backend= Specify the name of the pstore backend to use pt. [PARIDE] - See Documentation/blockdev/paride.txt. + See Documentation/admin-guide/blockdev/paride.rst. pti= [X86_64] Control Page Table Isolation of user and kernel address spaces. Disabling this feature @@ -3577,7 +3704,7 @@ See Documentation/admin-guide/md.rst. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes - See Documentation/blockdev/ramdisk.txt. + See Documentation/admin-guide/blockdev/ramdisk.rst. random.trust_cpu={on,off} [KNL] Enable or disable trusting the use of the @@ -3592,7 +3719,9 @@ see CONFIG_RAS_CEC help text. rcu_nocbs= [KNL] - The argument is a cpu list, as described above. + The argument is a cpu list, as described above, + except that the string "all" can be used to + specify every CPU on the system. In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. @@ -3639,6 +3768,12 @@ the propagation of recent CPU-hotplug changes up the rcu_node combining tree. + rcutree.use_softirq= [KNL] + If set to zero, move all RCU_SOFTIRQ processing to + per-CPU rcuc kthreads. Defaults to a non-zero + value, meaning that RCU_SOFTIRQ is used by default. + Specify rcutree.use_softirq=0 to use rcuc kthreads. + rcutree.rcu_fanout_exact= [KNL] Disable autobalancing of the rcu_node combining tree. This is used by rcutorture, and might @@ -3653,19 +3788,6 @@ latencies, which will choose a value aligned with the appropriate hardware boundaries. - rcutree.jiffies_till_sched_qs= [KNL] - Set required age in jiffies for a - given grace period before RCU starts - soliciting quiescent-state help from - rcu_note_context_switch(). If not specified, the - kernel will calculate a value based on the most - recent settings of rcutree.jiffies_till_first_fqs - and rcutree.jiffies_till_next_fqs. - This calculated value may be viewed in - rcutree.jiffies_to_sched_qs. Any attempt to - set rcutree.jiffies_to_sched_qs will be - cheerfully overwritten. - rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to first attempt to force quiescent states. @@ -3677,6 +3799,20 @@ quiescent states. Units are jiffies, minimum value is one, and maximum value is HZ. + rcutree.jiffies_till_sched_qs= [KNL] + Set required age in jiffies for a + given grace period before RCU starts + soliciting quiescent-state help from + rcu_note_context_switch() and cond_resched(). + If not specified, the kernel will calculate + a value based on the most recent settings + of rcutree.jiffies_till_first_fqs + and rcutree.jiffies_till_next_fqs. + This calculated value may be viewed in + rcutree.jiffies_to_sched_qs. Any attempt to set + rcutree.jiffies_to_sched_qs will be cheerfully + overwritten. + rcutree.kthread_prio= [KNL,BOOT] Set the SCHED_FIFO priority of the RCU per-CPU kthreads (rcuc/N). This value is also used for @@ -3720,6 +3856,11 @@ This wake_up() will be accompanied by a WARN_ONCE() splat and an ftrace_dump(). + rcutree.sysrq_rcu= [KNL] + Commandeer a sysrq key to dump out Tree RCU's + rcu_node tree with an eye towards determining + why a new grace period has not yet started. + rcuperf.gp_async= [KNL] Measure performance of asynchronous grace-period primitives such as call_rcu(). @@ -3949,7 +4090,9 @@ [[,]s[mp]#### \ [[,]b[ios] | a[cpi] | k[bd] | t[riple] | e[fi] | p[ci]] \ [[,]f[orce] - Where reboot_mode is one of warm (soft) or cold (hard) or gpio, + Where reboot_mode is one of warm (soft) or cold (hard) or gpio + (prefix with 'panic_' to set mode for panic + reboot only), reboot_type is one of bios, acpi, kbd, triple, efi, or pci, reboot_force is either force or not specified, reboot_cpu is s[mp]#### with #### being the processor @@ -3957,7 +4100,7 @@ relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. - See Documentation/cgroup-v1/cpusets.txt. + See Documentation/admin-guide/cgroup-v1/cpusets.rst. reserve= [KNL,BUGS] Force kernel to ignore I/O ports or memory Format: <base1>,<size1>[,<base2>,<size2>,...] @@ -3987,7 +4130,7 @@ Specify the offset from the beginning of the partition given by "resume=" at which the swap header is located, in <PAGE_SIZE> units (needed only for swap files). - See Documentation/power/swsusp-and-swap-files.txt + See Documentation/power/swsusp-and-swap-files.rst resumedelay= [HIBERNATION] Delay (in seconds) to pause before attempting to read the resume files @@ -4089,11 +4232,9 @@ Note: increases power consumption, thus should only be enabled if running jitter sensitive (HPC/RT) workloads. - security= [SECURITY] Choose a security module to enable at boot. - If this boot parameter is not specified, only the first - security module asking for security registration will be - loaded. An invalid security module name will be treated - as if no module has been chosen. + security= [SECURITY] Choose a legacy "major" security module to + enable at boot. This has been deprecated by the + "lsm=" parameter. selinux= [SELINUX] Disable or enable SELinux at boot time. Format: { "0" | "1" } @@ -4217,7 +4358,7 @@ Format: <integer> sonypi.*= [HW] Sony Programmable I/O Control Device driver - See Documentation/laptops/sonypi.txt + See Documentation/admin-guide/laptops/sonypi.rst spectre_v2= [X86] Control mitigation of Spectre variant 2 (indirect branch speculation) vulnerability. @@ -4469,7 +4610,7 @@ swapaccount=[0|1] [KNL] Enable accounting of swap in memory resource controller if no parameter or 1 is given or disable - it if 0 is given (See Documentation/cgroup-v1/memory.txt) + it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) swiotlb= [ARM,IA-64,PPC,MIPS,X86] Format: { <int> | force | noforce } @@ -4668,6 +4809,10 @@ [x86] unstable: mark the TSC clocksource as unstable, this marks the TSC unconditionally unstable at bootup and avoids any further wobbles once the TSC watchdog notices. + [x86] nowatchdog: disable clocksource watchdog. Used + in situations with strict latency requirements (where + interruptions from clocksource watchdog are not + acceptable). turbografx.map[2|3]= [HW,JOY] TurboGraFX parallel port interface @@ -4697,7 +4842,8 @@ usbcore.authorized_default= [USB] Default USB device authorization: (default -1 = authorized except for wireless USB, - 0 = not authorized, 1 = authorized) + 0 = not authorized, 1 = authorized, 2 = authorized + if device connected to internal port) usbcore.autosuspend= [USB] The autosuspend time delay (in seconds) used @@ -4902,7 +5048,7 @@ vector=percpu: enable percpu vector domain video= [FB] Frame buffer configuration - See Documentation/fb/modedb.txt. + See Documentation/fb/modedb.rst. video.brightness_switch_enabled= [0,1] If set to 1, on receiving an ACPI notify event @@ -4930,8 +5076,8 @@ Can be used multiple times for multiple devices. vga= [BOOT,X86-32] Select a particular video mode - See Documentation/x86/boot.txt and - Documentation/svga.txt. + See Documentation/x86/boot.rst and + Documentation/admin-guide/svga.rst. Use vga=ask for menu. This is actually a boot loader parameter; the value is passed to the kernel using a special protocol. @@ -4976,13 +5122,12 @@ targets for exploits that can control RIP. emulate [default] Vsyscalls turn into traps and are - emulated reasonably safely. + emulated reasonably safely. The vsyscall + page is readable. - native Vsyscalls are native syscall instructions. - This is a little bit faster than trapping - and makes a few dynamic recompilers work - better than they would in emulation mode. - It also makes exploits much easier to write. + xonly Vsyscalls turn into traps and are + emulated reasonably safely. The vsyscall + page is not readable. none Vsyscalls don't work at all. This makes them quite hard to use for exploits but @@ -5038,10 +5183,18 @@ Default: 3 = cyan. watchdog timers [HW,WDT] For information on watchdog timers, - see Documentation/watchdog/watchdog-parameters.txt + see Documentation/watchdog/watchdog-parameters.rst or other driver-specific files in the Documentation/watchdog/ directory. + watchdog_thresh= + [KNL] + Set the hard lockup detector stall duration + threshold in seconds. The soft lockup detector + threshold is set to twice the value. A value of 0 + disables both lockup detectors. Default is 10 + seconds. + workqueue.watchdog_thresh= If CONFIG_WQ_WATCHDOG is configured, workqueue can warn stall conditions and dump internal state to @@ -5129,10 +5282,26 @@ with /sys/devices/system/xen_memory/xen_memory0/scrub_pages. Default value controlled with CONFIG_XEN_SCRUB_PAGES_DEFAULT. + xen_timer_slop= [X86-64,XEN] + Set the timer slop (in nanoseconds) for the virtual Xen + timers (default is 100000). This adjusts the minimum + delta of virtualized Xen timers, where lower values + improve timer resolution at the expense of processing + more timer interrupts. + xirc2ps_cs= [NET,PCMCIA] Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] + xive= [PPC] + By default on POWER9 and above, the kernel will + natively use the XIVE interrupt controller. This option + allows the fallback firmware mode to be used: + + off Fallback to firmware control of XIVE interrupt + controller on both pseries and powernv + platforms. Only useful on POWER9 and above. + xhci-hcd.quirks [USB,KNL] A hex value specifying bitmask with supplemental xhci host controller quirks. Meaning of each bit can be |