diff options
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 161 |
1 files changed, 131 insertions, 30 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index c07815d230bc..7bc83f3d9bdf 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -22,11 +22,13 @@ default: 0 acpi_backlight= [HW,ACPI] - acpi_backlight=vendor - acpi_backlight=video - If set to vendor, prefer vendor specific driver + { vendor | video | native | none } + If set to vendor, prefer vendor-specific driver (e.g. thinkpad_acpi, sony_acpi, etc.) instead of the ACPI video.ko driver. + If set to video, use the ACPI video.ko driver. + If set to native, use the device's native backlight mode. + If set to none, disable the ACPI backlight interface. acpi_force_32bit_fadt_addr force FADT to use 32 bit addresses rather than the @@ -450,6 +452,9 @@ bert_disable [ACPI] Disable BERT OS support on buggy BIOSes. + bgrt_disable [ACPI][X86] + Disable BGRT to avoid flickering OEM logo. + bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards) bttv.radio= Most important insmod options are available as kernel args too. @@ -522,6 +527,7 @@ Default value is set via a kernel config option. Value can be changed at runtime via /sys/fs/selinux/checkreqprot. + Setting checkreqprot to 1 is deprecated. cio_ignore= [S390] See Documentation/s390/common_io.rst for details. @@ -679,7 +685,7 @@ coredump_filter= [KNL] Change the default value for /proc/<pid>/coredump_filter. - See also Documentation/filesystems/proc.txt. + See also Documentation/filesystems/proc.rst. coresight_cpu_debug.enable [ARM,ARM64] @@ -956,7 +962,7 @@ 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/driver-api/edid.rst. An EDID + available in Documentation/admin-guide/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 @@ -986,10 +992,6 @@ Documentation/admin-guide/dynamic-debug-howto.rst for details. - nompx [X86] Disables Intel Memory Protection Extensions. - See Documentation/x86/intel_mpx.rst for more - information about the feature. - nopku [X86] Disable Memory Protection Keys CPU feature found in some Intel CPUs. @@ -1099,6 +1101,12 @@ A valid base address must be provided, and the serial port must already be setup and configured. + ec_imx21,<addr> + ec_imx6q,<addr> + Start an early, polled-mode, output-only console on the + Freescale i.MX UART at the specified address. The UART + must already be setup and configured. + ar3700_uart,<addr> Start an early, polled-mode console on the Armada 3700 serial port at the specified @@ -1354,6 +1362,24 @@ can be changed at run time by the max_graph_depth file in the tracefs tracing directory. default: 0 (no limit) + fw_devlink= [KNL] Create device links between consumer and supplier + devices by scanning the firmware to infer the + consumer/supplier relationships. This feature is + especially useful when drivers are loaded as modules as + it ensures proper ordering of tasks like device probing + (suppliers first, then consumers), supplier boot state + clean up (only after all consumers have probed), + suspend/resume & runtime PM (consumers first, then + suppliers). + Format: { off | permissive | on | rpm } + off -- Don't create device links from firmware info. + permissive -- Create device links from firmware info + but use it only for ordering boot state clean + up (sync_state() calls). + on -- Create device links from firmware info and use it + to enforce probe and suspend/resume ordering. + rpm -- Like "on", but also use to order runtime PM. + gamecon.map[2|3]= [HW,JOY] Multisystem joystick and NES/SNES/PSX pad support via parallel port (up to 5 devices per port) @@ -1445,6 +1471,14 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. + hugetlb_cma= [HW] The size of a cma area used for allocation + of gigantic hugepages. + Format: nn[KMGTPE] + + Reserve a cma area of given size and allocate gigantic + hugepages using the cma allocator. If enabled, the + boot-time allocation of gigantic hugepages is skipped. + hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot. hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. On x86-64 and powerpc, this option can be specified @@ -1779,7 +1813,7 @@ provided by tboot because it makes the system vulnerable to DMA attacks. nobounce [Default off] - Disable bounce buffer for unstrusted devices such as + Disable bounce buffer for untrusted devices such as the Thunderbolt devices. This will treat the untrusted devices as the trusted ones, hence might expose security risks of DMA attacks. @@ -1883,7 +1917,7 @@ No delay ip= [IP_PNP] - See Documentation/filesystems/nfs/nfsroot.txt. + See Documentation/admin-guide/nfs/nfsroot.rst. ipcmni_extend [KNL] Extend the maximum number of unique System V IPC identifiers from 32,768 to 16,777,216. @@ -2543,13 +2577,22 @@ 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. + Amount of memory to be used in cases as follows: + + 1 for test; + 2 when the kernel is not able to see the whole system memory; + 3 memory that lies after 'mem=' boundary is excluded from + the hypervisor, then assigned to KVM guests. + [X86] Work as limiting max address. Use together with memmap= to avoid physical address space collisions. Without memmap= PCI devices could be placed at addresses belonging to unused RAM. + Note that this only takes effects during boot time since + in above case 3, memory may need be hot added after boot + if system memory of hypervisor is not sufficient. + mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel memory. @@ -2795,7 +2838,7 @@ <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>] mtdparts= [MTD] - See drivers/mtd/cmdlinepart.c. + See drivers/mtd/parsers/cmdlinepart.c multitce=off [PPC] This parameter disables the use of the pSeries firmware feature for updating multiple TCE entries @@ -2853,13 +2896,13 @@ Default value is 0. nfsaddrs= [NFS] Deprecated. Use ip= instead. - See Documentation/filesystems/nfs/nfsroot.txt. + See Documentation/admin-guide/nfs/nfsroot.rst. nfsroot= [NFS] nfs root filesystem for disk-less boxes. - See Documentation/filesystems/nfs/nfsroot.txt. + See Documentation/admin-guide/nfs/nfsroot.rst. nfsrootdebug [NFS] enable nfsroot debugging messages. - See Documentation/filesystems/nfs/nfsroot.txt. + See Documentation/admin-guide/nfs/nfsroot.rst. nfs.callback_nr_threads= [NFSv4] set the total number of threads that the @@ -3174,7 +3217,7 @@ [X86,PV_OPS] Disable paravirtualized VMware scheduler clock and use the default one. - no-steal-acc [X86,KVM,ARM64] Disable paravirtualized steal time + no-steal-acc [X86,PV_OPS,ARM64] Disable paravirtualized steal time accounting. steal time is computed, but won't influence scheduler behaviour @@ -3285,12 +3328,6 @@ This can be set from sysctl after boot. See Documentation/admin-guide/sysctl/vm.rst for details. - of_devlink [OF, KNL] Create device links between consumer and - supplier devices by scanning the devictree to infer the - consumer/supplier relationships. A consumer device - will not be probed until all the supplier devices have - probed successfully. - ohci1394_dma=early [HW] enable debugging via the ohci1394 driver. See Documentation/debugging-via-ohci1394.txt for more info. @@ -3698,6 +3735,9 @@ Override pmtimer IOPort with a hex value. e.g. pmtmr=0x508 + pm_debug_messages [SUSPEND,KNL] + Enable suspend/resume debug messages during boot up. + pnp.debug=1 [PNP] Enable PNP debug messages (depends on the CONFIG_PNP_DEBUG_MESSAGES option). Change at run-time @@ -3799,6 +3839,11 @@ before loading. See Documentation/admin-guide/blockdev/ramdisk.rst. + prot_virt= [S390] enable hosting protected virtual machines + isolated from the hypervisor (if hardware supports + that). + Format: <bool> + psi= [KNL] Enable or disable pressure stall information tracking. Format: <bool> @@ -3984,6 +4029,15 @@ Set threshold of queued RCU callbacks below which batch limiting is re-enabled. + rcutree.qovld= [KNL] + Set threshold of queued RCU callbacks beyond which + RCU's force-quiescent-state scan will aggressively + enlist help from cond_resched() and sched IPIs to + help CPUs more quickly reach quiescent states. + Set to less than zero to make this be set based + on rcutree.qhimark at boot time and to zero to + disable more aggressive help enlistment. + rcutree.rcu_idle_gp_delay= [KNL] Set wakeup interval for idle CPUs that have RCU callbacks (RCU_FAST_NO_HZ=y). @@ -4199,6 +4253,12 @@ rcupdate.rcu_cpu_stall_suppress= [KNL] Suppress RCU CPU stall warning messages. + rcupdate.rcu_cpu_stall_suppress_at_boot= [KNL] + Suppress RCU CPU stall warning messages and + rcutorture writer stall warnings that occur + during early boot, that is, during the time + before the init task is spawned. + rcupdate.rcu_cpu_stall_timeout= [KNL] Set timeout for RCU CPU stall warning messages. @@ -4392,6 +4452,22 @@ incurs a small amount of overhead in the scheduler but is useful for debugging and performance tuning. + sched_thermal_decay_shift= + [KNL, SMP] Set a decay shift for scheduler thermal + pressure signal. Thermal pressure signal follows the + default decay period of other scheduler pelt + signals(usually 32 ms but configurable). Setting + sched_thermal_decay_shift will left shift the decay + period for the thermal pressure signal by the shift + value. + i.e. with the default pelt decay period of 32 ms + sched_thermal_decay_shift thermal pressure decay pr + 1 64 ms + 2 128 ms + and so on. + Format: integer between 0 and 10 + Default is 0. + skew_tick= [KNL] Offset the periodic timer tick per cpu to mitigate xtime_lock contention on larger systems, and/or RCU lock contention on all systems with CONFIG_MAXSMP set. @@ -4514,10 +4590,10 @@ Format: <integer> A nonzero value instructs the soft-lockup detector - to panic the machine when a soft-lockup occurs. This - is also controlled by CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC - which is the respective build-time switch to that - functionality. + to panic the machine when a soft-lockup occurs. It is + also controlled by the kernel.softlockup_panic sysctl + and CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC, which is the + respective build-time switch to that functionality. softlockup_all_cpu_backtrace= [KNL] Should the soft-lockup detector generate @@ -4659,6 +4735,28 @@ spia_pedr= spia_peddr= + split_lock_detect= + [X86] Enable split lock detection + + When enabled (and if hardware support is present), atomic + instructions that access data across cache line + boundaries will result in an alignment check exception. + + off - not enabled + + warn - the kernel will emit rate limited warnings + about applications triggering the #AC + exception. This mode is the default on CPUs + that supports split lock detection. + + fatal - the kernel will send SIGBUS to applications + that trigger the #AC exception. + + If an #AC exception is hit in the kernel or in + firmware (i.e. not while executing in user mode) + the kernel will oops in either "warn" or "fatal" + mode. + srcutree.counter_wrap_check [KNL] Specifies how frequently to check for grace-period sequence counter wrap for the @@ -4871,6 +4969,10 @@ topology updates sent by the hypervisor to this LPAR. + torture.disable_onoff_at_boot= [KNL] + Prevent the CPU-hotplug component of torturing + until after init has spawned. + tp720= [HW,PS2] tpm_suspend_pcr=[HW,TPM] @@ -5085,8 +5187,7 @@ usbcore.old_scheme_first= [USB] Start with the old device initialization - scheme, applies only to low and full-speed devices - (default 0 = off). + scheme (default 0 = off). usbcore.usbfs_memory_mb= [USB] Memory limit (in MB) for buffers allocated by |