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Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 743 |
1 files changed, 611 insertions, 132 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 363e348bff9..b7fa2f59945 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1,27 +1,37 @@ Kernel Parameters ~~~~~~~~~~~~~~~~~ -The following is a consolidated list of the kernel parameters as implemented -(mostly) by the __setup() macro and sorted into English Dictionary order -(defined as ignoring all punctuation and sorting digits before letters in a -case insensitive manner), and with descriptions where known. - -Module parameters for loadable modules are specified only as the -parameter name with optional '=' and value as appropriate, such as: - - modprobe usbcore blinkenlights=1 - -Module parameters for modules that are built into the kernel image -are specified on the kernel command line with the module name plus -'.' plus parameter name, with '=' and value if appropriate, such as: - - usbcore.blinkenlights=1 +The following is a consolidated list of the kernel parameters as +implemented by the __setup(), core_param() and module_param() macros +and sorted into English Dictionary order (defined as ignoring all +punctuation and sorting digits before letters in a case insensitive +manner), and with descriptions where known. + +The kernel parses parameters from the kernel command line up to "--"; +if it doesn't recognize a parameter and it doesn't contain a '.', the +parameter gets passed to init: parameters with '=' go into init's +environment, others are passed as command line arguments to init. +Everything after "--" is passed as an argument to init. + +Module parameters can be specified in two ways: via the kernel command +line with a module name prefix, or via modprobe, e.g.: + + (kernel command line) usbcore.blinkenlights=1 + (modprobe command line) modprobe usbcore blinkenlights=1 + +Parameters for modules which are built into the kernel need to be +specified on the kernel command line. modprobe looks through the +kernel command line (/proc/cmdline) and collects module parameters +when it loads a module, so the kernel command line can be used for +loadable modules too. Hyphens (dashes) and underscores are equivalent in parameter names, so log_buf_len=1M print-fatal-signals=1 can also be entered as log-buf-len=1M print_fatal_signals=1 +Double-quotes can be used to protect spaces in values, e.g.: + param="spaces in here" This document may not be entirely up to date and comprehensive. The command "modinfo -p ${modulename}" shows a current list of all parameters of a loadable @@ -44,6 +54,8 @@ parameter is applicable: AVR32 AVR32 architecture is enabled. AX25 Appropriate AX.25 support is enabled. BLACKFIN Blackfin architecture is enabled. + CLK Common clock infrastructure is enabled. + CMA Contiguous Memory Area support is enabled. DRM Direct Rendering Management support is enabled. DYNAMIC_DEBUG Build in debug messages and enable them at runtime EDD BIOS Enhanced Disk Drive Services (EDD) is enabled @@ -212,6 +224,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. unusable. The "log_buf_len" parameter may be useful if you need to capture more output. + acpi_force_table_verification [HW,ACPI] + Enable table checksum verification during early stage. + By default, this is disabled due to x86 early mapping + size limitation. + acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs default in APIC mode @@ -227,16 +244,91 @@ bytes respectively. Such letter suffixes can also be entirely omitted. use by PCI Format: <irq>,<irq>... - acpi_no_auto_ssdt [HW,ACPI] Disable automatic loading of SSDT + acpi_no_auto_serialize [HW,ACPI] + Disable auto-serialization of AML methods + AML control methods that contain the opcodes to create + named objects will be marked as "Serialized" by the + auto-serialization feature. + This feature is enabled by default. + This option allows to turn off the feature. + + acpi_no_static_ssdt [HW,ACPI] + Disable installation of static SSDTs at early boot time + By default, SSDTs contained in the RSDT/XSDT will be + installed automatically and they will appear under + /sys/firmware/acpi/tables. + This option turns off this feature. + Note that specifying this option does not affect + dynamic table installation which will install SSDT + tables to /sys/firmware/acpi/tables/dynamic. + + acpica_no_return_repair [HW, ACPI] + Disable AML predefined validation mechanism + This mechanism can repair the evaluation result to make + the return objects more ACPI specification compliant. + This option is useful for developers to identify the + root cause of an AML interpreter issue when the issue + has something to do with the repair mechanism. acpi_os_name= [HW,ACPI] Tell ACPI BIOS the name of the OS Format: To spoof as Windows 98: ="Microsoft Windows" acpi_osi= [HW,ACPI] Modify list of supported OS interface strings - acpi_osi="string1" # add string1 -- only one string - acpi_osi="!string2" # remove built-in string2 + acpi_osi="string1" # add string1 + acpi_osi="!string2" # remove string2 + acpi_osi=!* # remove all strings + acpi_osi=! # disable all built-in OS vendor + strings acpi_osi= # disable all strings + 'acpi_osi=!' can be used in combination with single or + multiple 'acpi_osi="string1"' to support specific OS + vendor string(s). Note that such command can only + affect the default state of the OS vendor strings, thus + it cannot affect the default state of the feature group + strings and the current state of the OS vendor strings, + specifying it multiple times through kernel command line + is meaningless. This command is useful when one do not + care about the state of the feature group strings which + should be controlled by the OSPM. + Examples: + 1. 'acpi_osi=! acpi_osi="Windows 2000"' is equivalent + to 'acpi_osi="Windows 2000" acpi_osi=!', they all + can make '_OSI("Windows 2000")' TRUE. + + 'acpi_osi=' cannot be used in combination with other + 'acpi_osi=' command lines, the _OSI method will not + exist in the ACPI namespace. NOTE that such command can + only affect the _OSI support state, thus specifying it + multiple times through kernel command line is also + meaningless. + Examples: + 1. 'acpi_osi=' can make 'CondRefOf(_OSI, Local1)' + FALSE. + + 'acpi_osi=!*' can be used in combination with single or + multiple 'acpi_osi="string1"' to support specific + string(s). Note that such command can affect the + current state of both the OS vendor strings and the + feature group strings, thus specifying it multiple times + through kernel command line is meaningful. But it may + still not able to affect the final state of a string if + there are quirks related to this string. This command + is useful when one want to control the state of the + feature group strings to debug BIOS issues related to + the OSPM features. + Examples: + 1. 'acpi_osi="Module Device" acpi_osi=!*' can make + '_OSI("Module Device")' FALSE. + 2. 'acpi_osi=!* acpi_osi="Module Device"' can make + '_OSI("Module Device")' TRUE. + 3. 'acpi_osi=! acpi_osi=!* acpi_osi="Windows 2000"' is + equivalent to + 'acpi_osi=!* acpi_osi=! acpi_osi="Windows 2000"' + and + 'acpi_osi=!* acpi_osi="Windows 2000" acpi_osi=!', + they all will make '_OSI("Windows 2000")' TRUE. + acpi_pm_good [X86] Override the pmtimer bug detection: force the kernel to assume that this machine's pmtimer latches its value @@ -245,8 +337,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted. acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode Format: { level | edge | high | low } - acpi_serialize [HW,ACPI] force serialization of AML methods - acpi_skip_timer_override [HW,ACPI] Recognize and ignore IRQ0/pin2 Interrupt Override. For broken nForce2 BIOS resulting in XT-PIC timer. @@ -290,6 +380,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. no: ACPI OperationRegions are not marked as reserved, no further checks are performed. + acpi_no_memhotplug [ACPI] Disable memory hotplug. Useful for kdump + kernels. + add_efi_memmap [EFI; X86] Include EFI memory map in kernel's map of available physical RAM. @@ -320,6 +413,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. on: enable for both 32- and 64-bit processes off: disable for both 32- and 64-bit processes + alloc_snapshot [FTRACE] + Allocate the ftrace snapshot buffer on boot up when the + main buffer is allocated. This is handy if debugging + and you need to use tracing_snapshot() on boot up, and + do not want to use tracing_snapshot_alloc() as it needs + to be done where GFP_KERNEL allocations are allowed. + amd_iommu= [HW,X86-64] Pass parameters to the AMD IOMMU driver in the system. Possible values are: @@ -403,6 +503,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted. atkbd.softrepeat= [HW] Use software keyboard repeat + audit= [KNL] Enable the audit sub-system + Format: { "0" | "1" } (0 = disabled, 1 = enabled) + 0 - kernel audit is disabled and can not be enabled + until the next reboot + unset - kernel audit is initialized but disabled and + will be fully enabled by the userspace auditd. + 1 - kernel audit is initialized and partially enabled, + storing at most audit_backlog_limit messages in + RAM until it is fully enabled by the userspace + auditd. + Default: unset + + audit_backlog_limit= [KNL] Set the audit queue size limit. + Format: <int> (must be >=0) + Default: 64 + baycom_epp= [HW,AX25] Format: <io>,<mode> @@ -420,6 +536,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: <io>,<irq>,<mode> See header of drivers/net/hamradio/baycom_ser_hdx.c. + blkdevparts= Manual partition parsing of block device(s) for + embedded devices based on command line input. + See Documentation/block/cmdline-partition.txt + boot_delay= Milliseconds to delay each printk during boot. Values larger than 10 seconds (10000) are changed to no delay (0). @@ -451,7 +571,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. cgroup_disable= [KNL] Disable a particular controller Format: {name of the controller(s) to disable} - {Currently supported controllers - "memory"} + The effects of cgroup_disable=foo are: + - foo isn't auto-mounted if you mount all cgroups in + a single hierarchy + - foo isn't visible as an individually mountable + subsystem + {Currently only "memory" controller deal with this and + cut the overhead, others just disable the usage. So + only cgroup_disable=memory is actually worthy} checkreqprot [SELINUX] Set initial checkreqprot flag value. Format: { "0" | "1" } @@ -465,6 +592,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. cio_ignore= [S390] See Documentation/s390/CommonIO for details. + clk_ignore_unused + [CLK] + Keep all clocks already enabled by bootloader on, + even if no driver has claimed them. This is useful + for debug and development, but should not be + needed on a platform with proper driver support. + For more information, see Documentation/clk.txt. clock= [BUGS=X86-32, HW] gettimeofday clocksource override. [Deprecated] @@ -506,8 +640,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Also note the kernel might malfunction if you disable some critical bits. - cma=nn[MG] [ARM,KNL] - Sets the size of kernel global memory area for contiguous + cma=nn[MG]@[start[MG][-end[MG]]] + [ARM,X86,KNL] + Sets the size of kernel global memory area for + contiguous memory allocations and optionally the + placement constraint by the physical address range of memory allocations. For more information, see include/linux/dma-contiguous.h @@ -564,6 +701,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. UART at the specified I/O port or MMIO address, switching to the matching ttyS device later. The options are the same as for ttyS, above. + hvc<n> Use the hypervisor console device <n>. This is for + both Xen and PowerPC hypervisors. If the device connected to the port is not a TTY but a braille device, prepend "brl," before the device type, for instance @@ -601,6 +740,26 @@ bytes respectively. Such letter suffixes can also be entirely omitted. a memory unit (amount[KMG]). See also Documentation/kdump/kdump.txt for an example. + crashkernel=size[KMG],high + [KNL, x86_64] range could be above 4G. Allow kernel + to allocate physical memory region from top, so could + be above 4G if system have more than 4G ram installed. + Otherwise memory region will be allocated below 4G, if + available. + It will be ignored if crashkernel=X is specified. + crashkernel=size[KMG],low + [KNL, x86_64] range under 4G. When crashkernel=X,high + is passed, kernel could allocate physical memory region + above 4G, that cause second kernel crash on system + that require some amount of low memory, e.g. swiotlb + requires at least 64M+32K low memory. Kernel would + try to allocate 72M below 4G automatically. + This one let user to specify own low range under 4G + for second kernel instead. + 0: to disable low allocation. + It will be ignored when crashkernel=X,high is not used + or memory reserved is below 4G. + cs89x0_dma= [HW,NET] Format: <dma> @@ -671,16 +830,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted. dhash_entries= [KNL] Set number of hash buckets for dentry cache. - digi= [HW,SERIAL] - IO parameters + enable/disable command. - - digiepca= [HW,SERIAL] - See drivers/char/README.epca and - Documentation/serial/digiepca.txt. - disable= [IPV6] See Documentation/networking/ipv6.txt. + disable_cpu_apicid= [X86,APIC,SMP] + Format: <int> + The number of initial APIC ID for the + corresponding CPU to be disabled at boot, + mostly used for the kdump 2nd kernel to + disable BSP to wake up multiple CPUs without + causing system reset or hang due to sending + INIT from AP to BSP. + disable_ddw [PPC/PSERIES] Disable Dynamic DMA Window support. Use this if to workaround buggy firmware. @@ -742,7 +903,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Enable debug messages at boot time. See Documentation/dynamic-debug-howto.txt for details. + early_ioremap_debug [KNL] + Enable debug messages in early_ioremap support. This + is useful for tracking down temporary early mappings + which are not unmapped. + earlycon= [KNL] Output early console device and options. + uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] uart[8250],mmio32,<addr>[,options] @@ -752,24 +919,57 @@ bytes respectively. Such letter suffixes can also be entirely omitted. (mmio) or 32-bit (mmio32). The options are the same as for ttyS, above. - earlyprintk= [X86,SH,BLACKFIN] + pl011,<addr> + Start an early, polled-mode console on a pl011 serial + port at the specified address. The pl011 serial port + must already be setup and configured. Options are not + yet supported. + + smh Use ARM semihosting calls for early console. + + earlyprintk= [X86,SH,BLACKFIN,ARM,M68k] earlyprintk=vga + earlyprintk=efi + earlyprintk=xen earlyprintk=serial[,ttySn[,baudrate]] + earlyprintk=serial[,0x...[,baudrate]] earlyprintk=ttySn[,baudrate] earlyprintk=dbgp[debugController#] + earlyprintk is useful when the kernel crashes before + the normal console is initialized. It is not enabled by + default because it has some cosmetic problems. + Append ",keep" to not disable it when the real console takes over. - Only vga or serial or usb debug port at a time. + Only one of vga, efi, serial, or usb debug port can + be used at a time. - Currently only ttyS0 and ttyS1 are supported. + Currently only ttyS0 and ttyS1 may be specified by + name. Other I/O ports may be explicitly specified + on some architectures (x86 and arm at least) by + replacing ttySn with an I/O port address, like this: + earlyprintk=serial,0x1008,115200 + You can find the port for a given device in + /proc/tty/driver/serial: + 2: uart:ST16650V2 port:00001008 irq:18 ... Interaction with the standard serial driver is not very good. - The VGA output is eventually overwritten by the real - console. + The VGA and EFI output is eventually overwritten by + the real console. + + The xen output can only be used by Xen PV guests. + + edac_report= [HW,EDAC] Control how to report EDAC event + Format: {"on" | "off" | "force"} + on: enable EDAC to report H/W event. May be overridden + by other higher priority error reporting module. + off: disable H/W event reporting through EDAC. + force: enforce the use of EDAC to report H/W event. + default: on. ekgdboc= [X86,KGDB] Allow early kernel console debugging ekgdboc=kbd @@ -780,6 +980,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted. edd= [EDD] Format: {"off" | "on" | "skip[mbr]"} + efi= [EFI] + Format: { "old_map" } + old_map [X86-64]: switch to the old ioremap-based EFI + runtime services mapping. 32-bit still uses this one by + default. + + efi_no_storage_paranoia [EFI; X86] + Using this parameter you can use more than 50% of + your efi variable storage. Use this parameter only if + you are really sure that your UEFI does sane gc and + fulfills the spec otherwise your board may brick. + eisa_irq_edge= [PARISC,HW] See header of drivers/parisc/eisa.c. @@ -846,6 +1058,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. parameter will force ia64_sal_cache_flush to call ia64_pal_cache_flush instead of SAL_CACHE_FLUSH. + forcepae [X86-32] + Forcefully enable Physical Address Extension (PAE). + Many Pentium M systems disable PAE but may have a + functionally usable PAE implementation. + Warning: use of this parameter will taint the kernel + and may cause unknown problems. + ftrace=[tracer] [FTRACE] will set and start the specified tracer as early as possible in order to facilitate early @@ -897,7 +1116,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. debugfs files are removed at module unload time. gpt [EFI] Forces disk with valid GPT signature but - invalid Protective MBR to be treated as GPT. + invalid Protective MBR to be treated as GPT. If the + primary GPT is corrupted, it enables the backup/alternate + GPT to be used instead. grcan.enable0= [HW] Configuration of physical interface 0. Determines the "Enable 0" bit of the configuration register. @@ -954,6 +1175,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. VIA, nVidia) verbose: show contents of HPET registers during setup + hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET + registers. Default set by CONFIG_HPET_MMAP_DEFAULT. + 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 @@ -970,6 +1194,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. If specified, z/VM IUCV HVC accepts connections from listed z/VM user IDs only. + hwthread_map= [METAG] Comma-separated list of Linux cpu id to + hardware thread id mappings. + Format: <cpu>:<hwthread> + keep_bootcon [KNL] Do not unregister boot console at start. This is only useful for debugging when something happens in the window @@ -1039,16 +1267,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Claim all unknown PCI IDE storage controllers. idle= [X86] - Format: idle=poll, idle=mwait, idle=halt, idle=nomwait + Format: idle=poll, idle=halt, idle=nomwait Poll forces a polling idle loop that can slightly improve the performance of waking up a idle CPU, but will use a lot of power and make the system run hot. Not recommended. - idle=mwait: On systems which support MONITOR/MWAIT but - the kernel chose to not use it because it doesn't save - as much power as a normal idle loop, use the - MONITOR/MWAIT idle loop anyways. Performance should be - the same as idle=poll. idle=halt: Halt is forced to be used for CPU idle. In such case C2/C3 won't be used again. idle=nomwait: Disable mwait for CPU C-states @@ -1071,21 +1294,25 @@ bytes respectively. Such letter suffixes can also be entirely omitted. The builtin appraise policy appraises all files owned by uid=0. - ima_audit= [IMA] - Format: { "0" | "1" } - 0 -- integrity auditing messages. (Default) - 1 -- enable informational integrity auditing messages. - ima_hash= [IMA] - Format: { "sha1" | "md5" } + Format: { md5 | sha1 | rmd160 | sha256 | sha384 + | sha512 | ... } default: "sha1" + The list of supported hash algorithms is defined + in crypto/hash_info.h. + ima_tcb [IMA] Load a policy which meets the needs of the Trusted Computing Base. This means IMA will measure all programs exec'd, files mmap'd for exec, and all files opened for read by uid=0. + ima_template= [IMA] + Select one of defined IMA measurements template formats. + Formats: { "ima" | "ima-ng" } + Default: "ima-ng" + init= [KNL] Format: <full_path> Run specified binary instead of /sbin/init as init @@ -1095,11 +1322,22 @@ bytes respectively. Such letter suffixes can also be entirely omitted. for working out where the kernel is dying during startup. + initcall_blacklist= [KNL] Do not execute a comma-separated list of + initcall functions. Useful for debugging built-in + modules and initcalls. + initrd= [BOOT] Specify the location of the initial ramdisk inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver Format: <irq> + int_pln_enable [x86] Enable power limit notification interrupt + + integrity_audit=[IMA] + Format: { "0" | "1" } + 0 -- basic integrity auditing messages. (Default) + 1 -- additional integrity auditing messages. + intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option on Enable intel iommu driver. @@ -1131,6 +1369,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 0 disables intel_idle and fall back on acpi_idle. 1 to 6 specify maximum depth of C-state. + intel_pstate= [X86] + disable + Do not enable intel_pstate as the default + scaling driver for the supported processors + intremap= [X86-64, Intel-IOMMU] on enable Interrupt Remapping (default) off disable Interrupt Remapping @@ -1214,9 +1457,30 @@ bytes respectively. Such letter suffixes can also be entirely omitted. iucv= [HW,NET] + ivrs_ioapic [HW,X86_64] + Provide an override to the IOAPIC-ID<->DEVICE-ID + mapping provided in the IVRS ACPI table. For + example, to map IOAPIC-ID decimal 10 to + PCI device 00:14.0 write the parameter as: + ivrs_ioapic[10]=00:14.0 + + ivrs_hpet [HW,X86_64] + Provide an override to the HPET-ID<->DEVICE-ID + mapping provided in the IVRS ACPI table. For + example, to map HPET-ID decimal 0 to + PCI device 00:14.0 write the parameter as: + ivrs_hpet[0]=00:14.0 + js= [HW,JOY] Analog joystick See Documentation/input/joystick.txt. + kaslr/nokaslr [X86] + Enable/disable kernel and module base offset ASLR + (Address Space Layout Randomization) if built into + the kernel. When CONFIG_HIBERNATION is selected, + kASLR is disabled by default. When kASLR is enabled, + hibernation will be disabled. + keepinitrd [HW,ARM] kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter @@ -1227,7 +1491,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. pages. In the event, a node is too small to have both kernelcore and Movable pages, kernelcore pages will take priority and other nodes will have a larger number - of kernelcore pages. The Movable zone is used for the + of Movable pages. The Movable zone is used for the allocation of pages that may be reclaimed or moved by the page migration subsystem. This means that HugeTLB pages may not be allocated from this zone. @@ -1267,6 +1531,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Valid arguments: on, off Default: on + kmemcheck= [X86] Boot-time kmemcheck enable/disable/one-shot mode + Valid arguments: 0, 1, 2 + kmemcheck=0 (disabled) + kmemcheck=1 (enabled) + kmemcheck=2 (one-shot mode) + Default: 2 (one-shot mode) + kstack=N [X86] Print N words from the kernel stack in oops dumps. @@ -1379,6 +1650,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. * dump_id: dump IDENTIFY data. + * atapi_dmadir: Enable ATAPI DMADIR bridge support + + * disable: Disable this device. + If there are multiple matching configurations changing the same attribute, the last one is used. @@ -1516,16 +1791,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted. option description. memmap=nn[KMG]@ss[KMG] - [KNL] Force usage of a specific region of memory - Region of memory to be used, from ss to ss+nn. + [KNL] Force usage of a specific region of memory. + Region of memory to be used is from ss to ss+nn. memmap=nn[KMG]#ss[KMG] [KNL,ACPI] Mark specific memory as ACPI data. - Region of memory to be used, from ss to ss+nn. + Region of memory to be marked is from ss to ss+nn. memmap=nn[KMG]$ss[KMG] [KNL,ACPI] Mark specific memory as reserved. - Region of memory to be used, from ss to ss+nn. + Region of memory to be reserved is from ss to ss+nn. Example: Exclude memory from 0x18690000-0x1869ffff memmap=64K$0x18690000 or @@ -1613,7 +1888,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. module.sig_enforce [KNL] When CONFIG_MODULE_SIG is set, this means that modules without (valid) signatures will fail to load. - Note that if CONFIG_MODULE_SIG_ENFORCE is set, that + Note that if CONFIG_MODULE_SIG_FORCE is set, that is always true, so this option does nothing. mousedev.tap_time= @@ -1637,6 +1912,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. that the amount of memory usable for all allocations is not too small. + movable_node [KNL,X86] Boot-time switch to enable the effects + of CONFIG_MOVABLE_NODE=y. See mm/Kconfig for details. + MTD_Partition= [MTD] Format: <name>,<region-number>,<size>,<offset> @@ -1766,6 +2044,18 @@ bytes respectively. Such letter suffixes can also be entirely omitted. will be sent. The default is to send the implementation identification information. + + nfs.recover_lost_locks = + [NFSv4] Attempt to recover locks that were lost due + to a lease timeout on the server. Please note that + doing this risks data corruption, since there are + no guarantees that the file will remain unchanged + after the locks are lost. + If you want to enable the kernel legacy behaviour of + attempting to recover these locks, then set this + parameter to '1'. + The default parameter value of '0' causes the kernel + not to attempt recovery of lost locks. nfsd.nfs4_disable_idmapping= [NFSv4] When set to the default of '1', the NFSv4 @@ -1886,10 +2176,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted. wfi(ARM) instruction doesn't work correctly and not to use it. This is also useful when using JTAG debugger. - no-hlt [BUGS=X86-32] Tells the kernel that the hlt - instruction doesn't work correctly and not to - use it. - no_file_caps Tells the kernel not to honor file capabilities. The only way then for a file to be executed with privilege is to be setuid root or executed by root. @@ -1901,10 +2187,20 @@ bytes respectively. Such letter suffixes can also be entirely omitted. in certain environments such as networked servers or real-time systems. + nohibernate [HIBERNATION] Disable hibernation and resume. + nohz= [KNL] Boottime enable/disable dynamic ticks Valid arguments: on, off Default: on + nohz_full= [KNL,BOOT] + In kernels built with CONFIG_NO_HZ_FULL=y, set + the specified list of CPUs whose tick will be stopped + whenever possible. The boot CPU will be forced outside + the range to maintain the timekeeping. + The CPUs in this range must also be included in the + rcu_nocbs= set. + noiotrap [SH] Disables trapped I/O port accesses. noirqdebug [X86-32] Disables the code which attempts to detect and @@ -1966,12 +2262,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. noreplace-smp [X86-32,SMP] Don't replace SMP instructions with UP alternatives - noresidual [PPC] Don't use residual data on PReP machines. - - nordrand [X86] Disable the direct use of the RDRAND - instruction even if it is supported by the - processor. RDRAND is still available to user - space applications. + nordrand [X86] Disable kernel use of the RDRAND and + RDSEED instructions even if they are supported + by the processor. RDRAND and RDSEED are still + available to user space applications. noresume [SWSUSP] Disables resume and restores original swap space. @@ -2082,6 +2376,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. timeout < 0: reboot immediately Format: <timeout> + crash_kexec_post_notifiers + Run kdump after running panic-notifiers and dumping + kmsg. This only for the users who doubt kdump always + succeeds in any situation. + Note that this also increases risks of kdump failure, + because some panic notifiers can make the crashed + kernel more unstable. + parkbd.port= [HW] Parallel port number the keyboard adapter is connected to, default is 0. Format: <parport#> @@ -2227,6 +2529,21 @@ bytes respectively. Such letter suffixes can also be entirely omitted. This sorting is done to get a device order compatible with older (<= 2.4) kernels. nobfsort Don't sort PCI devices into breadth-first order. + pcie_bus_tune_off Disable PCIe MPS (Max Payload Size) + tuning and use the BIOS-configured MPS defaults. + pcie_bus_safe Set every device's MPS to the largest value + supported by all devices below the root complex. + pcie_bus_perf Set device MPS to the largest allowable MPS + based on its parent bus. Also set MRRS (Max + Read Request Size) to the largest supported + value (no larger than the MPS that the device + or bus can support) for best performance. + pcie_bus_peer2peer Set every device's MPS to 128B, which + every device is guaranteed to support. This + configuration allows peer-to-peer DMA between + any pair of devices, possibly at the cost of + reduced performance. This also guarantees + that hot-added devices will work. cbiosize=nn[KMG] The fixed amount of bus space which is reserved for the CardBus bridge's IO window. The default value is 256 bytes. @@ -2248,6 +2565,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. the default. off: Turn ECRC off on: Turn ECRC on. + hpiosize=nn[KMG] The fixed amount of bus space which is + reserved for hotplug bridge's IO window. + Default size is 256 bytes. + hpmemsize=nn[KMG] The fixed amount of bus space which is + reserved for hotplug bridge's memory window. + Default size is 2 megabytes. realloc= Enable/disable reallocating PCI bridge resources if allocations done by BIOS are too small to accommodate resources required by all child @@ -2285,6 +2608,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. pcmv= [HW,PCMCIA] BadgePAD 4 + pd_ignore_unused + [PM] + Keep all power-domains already enabled by bootloader on, + even if no driver has claimed them. This is useful + for debug and development, but should not be + needed on a platform with proper driver support. + pd. [PARIDE] See Documentation/blockdev/paride.txt. @@ -2428,17 +2758,19 @@ bytes respectively. Such letter suffixes can also be entirely omitted. ramdisk_size= [RAM] Sizes of RAM disks in kilobytes See Documentation/blockdev/ramdisk.txt. - rcu_nocbs= [KNL,BOOT] + rcu_nocbs= [KNL] In kernels built with CONFIG_RCU_NOCB_CPU=y, set the specified list of CPUs to be no-callback CPUs. Invocation of these CPUs' RCU callbacks will - be offloaded to "rcuoN" kthreads created for - that purpose. This reduces OS jitter on the + be offloaded to "rcuox/N" kthreads created for + that purpose, where "x" is "b" for RCU-bh, "p" + for RCU-preempt, and "s" for RCU-sched, and "N" + is the CPU number. This reduces OS jitter on the offloaded CPUs, which can be useful for HPC and real-time workloads. It can also improve energy efficiency for asymmetric multiprocessors. - rcu_nocbs_poll [KNL,BOOT] + rcu_nocb_poll [KNL] Rather than requiring that offloaded CPUs (specified by rcu_nocbs= above) explicitly awaken the corresponding "rcuoN" kthreads, @@ -2449,129 +2781,179 @@ bytes respectively. Such letter suffixes can also be entirely omitted. energy efficiency by requiring that the kthreads periodically wake up to do the polling. - rcutree.blimit= [KNL,BOOT] - Set maximum number of finished RCU callbacks to process - in one batch. + rcutree.blimit= [KNL] + Set maximum number of finished RCU callbacks to + process in one batch. - rcutree.fanout_leaf= [KNL,BOOT] + rcutree.rcu_fanout_leaf= [KNL] Increase the number of CPUs assigned to each leaf rcu_node structure. Useful for very large systems. - rcutree.qhimark= [KNL,BOOT] - Set threshold of queued - RCU callbacks over which batch limiting is disabled. - - rcutree.qlowmark= [KNL,BOOT] - Set threshold of queued RCU callbacks below which - batch limiting is re-enabled. - - rcutree.rcu_cpu_stall_suppress= [KNL,BOOT] - Suppress RCU CPU stall warning messages. + 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(). - rcutree.rcu_cpu_stall_timeout= [KNL,BOOT] - Set timeout for RCU CPU stall warning messages. - - rcutree.jiffies_till_first_fqs= [KNL,BOOT] + rcutree.jiffies_till_first_fqs= [KNL] Set delay from grace-period initialization to first attempt to force quiescent states. Units are jiffies, minimum value is zero, and maximum value is HZ. - rcutree.jiffies_till_next_fqs= [KNL,BOOT] + rcutree.jiffies_till_next_fqs= [KNL] Set delay between subsequent attempts to force quiescent states. Units are jiffies, minimum value is one, and maximum value is HZ. - rcutorture.fqs_duration= [KNL,BOOT] + rcutree.qhimark= [KNL] + Set threshold of queued RCU callbacks beyond which + batch limiting is disabled. + + rcutree.qlowmark= [KNL] + Set threshold of queued RCU callbacks below which + batch limiting is re-enabled. + + rcutree.rcu_idle_gp_delay= [KNL] + Set wakeup interval for idle CPUs that have + RCU callbacks (RCU_FAST_NO_HZ=y). + + rcutree.rcu_idle_lazy_gp_delay= [KNL] + Set wakeup interval for idle CPUs that have + only "lazy" RCU callbacks (RCU_FAST_NO_HZ=y). + Lazy RCU callbacks are those which RCU can + prove do nothing more than free memory. + + rcutorture.fqs_duration= [KNL] Set duration of force_quiescent_state bursts. - rcutorture.fqs_holdoff= [KNL,BOOT] + rcutorture.fqs_holdoff= [KNL] Set holdoff time within force_quiescent_state bursts. - rcutorture.fqs_stutter= [KNL,BOOT] + rcutorture.fqs_stutter= [KNL] Set wait time between force_quiescent_state bursts. - rcutorture.irqreader= [KNL,BOOT] - Test RCU readers from irq handlers. + rcutorture.gp_exp= [KNL] + Use expedited update-side primitives. + + rcutorture.gp_normal= [KNL] + Use normal (non-expedited) update-side primitives. + If both gp_exp and gp_normal are set, do both. + If neither gp_exp nor gp_normal are set, still + do both. - rcutorture.n_barrier_cbs= [KNL,BOOT] + rcutorture.n_barrier_cbs= [KNL] Set callbacks/threads for rcu_barrier() testing. - rcutorture.nfakewriters= [KNL,BOOT] + rcutorture.nfakewriters= [KNL] Set number of concurrent RCU writers. These just stress RCU, they don't participate in the actual test, hence the "fake". - rcutorture.nreaders= [KNL,BOOT] + rcutorture.nreaders= [KNL] Set number of RCU readers. - rcutorture.onoff_holdoff= [KNL,BOOT] + rcutorture.object_debug= [KNL] + Enable debug-object double-call_rcu() testing. + + rcutorture.onoff_holdoff= [KNL] Set time (s) after boot for CPU-hotplug testing. - rcutorture.onoff_interval= [KNL,BOOT] + rcutorture.onoff_interval= [KNL] Set time (s) between CPU-hotplug operations, or zero to disable CPU-hotplug testing. - rcutorture.shuffle_interval= [KNL,BOOT] + rcutorture.rcutorture_runnable= [BOOT] + Start rcutorture running at boot time. + + rcutorture.shuffle_interval= [KNL] Set task-shuffle interval (s). Shuffling tasks allows some CPUs to go into dyntick-idle mode during the rcutorture test. - rcutorture.shutdown_secs= [KNL,BOOT] + rcutorture.shutdown_secs= [KNL] Set time (s) after boot system shutdown. This is useful for hands-off automated testing. - rcutorture.stall_cpu= [KNL,BOOT] + rcutorture.stall_cpu= [KNL] Duration of CPU stall (s) to test RCU CPU stall warnings, zero to disable. - rcutorture.stall_cpu_holdoff= [KNL,BOOT] + rcutorture.stall_cpu_holdoff= [KNL] Time to wait (s) after boot before inducing stall. - rcutorture.stat_interval= [KNL,BOOT] + rcutorture.stat_interval= [KNL] Time (s) between statistics printk()s. - rcutorture.stutter= [KNL,BOOT] + rcutorture.stutter= [KNL] Time (s) to stutter testing, for example, specifying five seconds causes the test to run for five seconds, wait for five seconds, and so on. This tests RCU's ability to transition abruptly to and from idle. - rcutorture.test_boost= [KNL,BOOT] + rcutorture.test_boost= [KNL] Test RCU priority boosting? 0=no, 1=maybe, 2=yes. "Maybe" means test if the RCU implementation under test support RCU priority boosting. - rcutorture.test_boost_duration= [KNL,BOOT] + rcutorture.test_boost_duration= [KNL] Duration (s) of each individual boost test. - rcutorture.test_boost_interval= [KNL,BOOT] + rcutorture.test_boost_interval= [KNL] Interval (s) between each boost test. - rcutorture.test_no_idle_hz= [KNL,BOOT] + rcutorture.test_no_idle_hz= [KNL] Test RCU's dyntick-idle handling. See also the rcutorture.shuffle_interval parameter. - rcutorture.torture_type= [KNL,BOOT] + rcutorture.torture_type= [KNL] Specify the RCU implementation to test. - rcutorture.verbose= [KNL,BOOT] + rcutorture.verbose= [KNL] Enable additional printk() statements. + rcupdate.rcu_expedited= [KNL] + Use expedited grace-period primitives, for + example, synchronize_rcu_expedited() instead + of synchronize_rcu(). This reduces latency, + but can increase CPU utilization, degrade + real-time latency, and degrade energy efficiency. + + rcupdate.rcu_cpu_stall_suppress= [KNL] + Suppress RCU CPU stall warning messages. + + rcupdate.rcu_cpu_stall_timeout= [KNL] + Set timeout for RCU CPU stall warning messages. + rdinit= [KNL] Format: <full_path> Run specified binary instead of /init from the ramdisk, used for early userspace startup. See initrd. - reboot= [BUGS=X86-32,BUGS=ARM,BUGS=IA-64] Rebooting mode - Format: <reboot_mode>[,<reboot_mode2>[,...]] - See arch/*/kernel/reboot.c or arch/*/kernel/process.c + reboot= [KNL] + Format (x86 or x86_64): + [w[arm] | c[old] | h[ard] | s[oft] | g[pio]] \ + [[,]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, + 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 + to be used for rebooting. relax_domain_level= [KNL, SMP] Set scheduler's default relax_domain_level. See Documentation/cgroups/cpusets.txt. + relative_sleep_states= + [SUSPEND] Use sleep state labeling where the deepest + state available other than hibernation is always "mem". + Format: { "0" | "1" } + 0 -- Traditional sleep state labels. + 1 -- Relative sleep state labels. + reserve= [KNL,BUGS] Force the kernel to ignore some iomem area reservetop= [X86-32] @@ -2609,15 +2991,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. noresume Don't check if there's a hibernation image present during boot. nocompress Don't compress/decompress hibernation images. + no Disable hibernation and resume. retain_initrd [RAM] Keep initrd memory after extraction rhash_entries= [KNL,NET] Set number of hash buckets for route cache - riscom8= [HW,SERIAL] - Format: <io_board1>[,<io_board2>[,...<io_boardN>]] - ro [KNL] Mount root device read-only on boot root= [KNL] Root filesystem @@ -2634,6 +3014,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Useful for devices that are detected asynchronously (e.g. USB and MMC devices). + rproc_mem=nn[KMG][@address] + [KNL,ARM,CMA] Remoteproc physical memory block. + Memory area to be used by remote processor image, + managed by CMA. + rw [KNL] Mount root device read-write on boot S [KNL] Run init in single mode @@ -2751,12 +3136,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. [KNL] Should the soft-lockup detector generate panics. Format: <integer> + softlockup_all_cpu_backtrace= + [KNL] Should the soft-lockup detector generate + backtraces on all cpus. + Format: <integer> + sonypi.*= [HW] Sony Programmable I/O Control Device driver See Documentation/laptops/sonypi.txt - specialix= [HW,SERIAL] Specialix multi-serial port adapter - See Documentation/serial/specialix.txt. - spia_io_base= [HW,MTD] spia_fio_base= spia_pedr= @@ -2823,12 +3210,16 @@ bytes respectively. Such letter suffixes can also be entirely omitted. improve throughput, but will also increase the amount of memory reserved for use by the client. - swapaccount[=0|1] + 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/cgroups/memory.txt) - swiotlb= [IA-64] Number of I/O TLB slabs + swiotlb= [ARM,IA-64,PPC,MIPS,X86] + Format: { <int> | force } + <int> -- Number of I/O TLB slabs + force -- force using of bounce buffers even if they + wouldn't be automatically used by the kernel switches= [HW,M68k] @@ -2887,6 +3278,27 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Force threading of all interrupt handlers except those marked explicitly IRQF_NO_THREAD. + tmem [KNL,XEN] + Enable the Transcendent memory driver if built-in. + + tmem.cleancache=0|1 [KNL, XEN] + Default is on (1). Disable the usage of the cleancache + API to send anonymous pages to the hypervisor. + + tmem.frontswap=0|1 [KNL, XEN] + Default is on (1). Disable the usage of the frontswap + API to send swap pages to the hypervisor. If disabled + the selfballooning and selfshrinking are force disabled. + + tmem.selfballooning=0|1 [KNL, XEN] + Default is on (1). Disable the driving of swap pages + to the hypervisor. + + tmem.selfshrinking=0|1 [KNL, XEN] + Default is on (1). Partial swapoff that immediately + transfers pages from Xen hypervisor back to the + kernel based on different criteria. + topology= [S390] Format: {off | on} Specify if the kernel should make use of the cpu @@ -2930,6 +3342,19 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See also Documentation/trace/ftrace.txt "trace options" section. + traceoff_on_warning + [FTRACE] enable this option to disable tracing when a + warning is hit. This turns off "tracing_on". Tracing can + be enabled again by echoing '1' into the "tracing_on" + file located in /sys/kernel/debug/tracing/ + + This option is useful, as it disables the trace before + the WARNING dump is called, which prevents the trace to + be filled with content caused by the warning output. + + This option can also be set at run time via the sysctl + option: kernel/traceoff_on_warning + transparent_hugepage= [KNL] Format: [always|madvise|never] @@ -3075,14 +3500,24 @@ bytes respectively. Such letter suffixes can also be entirely omitted. of CONFIG_HIGHPTE. vdso= [X86,SH] - vdso=2: enable compat VDSO (default with COMPAT_VDSO) - vdso=1: enable VDSO (default) + On X86_32, this is an alias for vdso32=. Otherwise: + + vdso=1: enable VDSO (the default) vdso=0: disable VDSO mapping - vdso32= [X86] - vdso32=2: enable compat VDSO (default with COMPAT_VDSO) - vdso32=1: enable 32-bit VDSO (default) - vdso32=0: disable 32-bit VDSO mapping + vdso32= [X86] Control the 32-bit vDSO + vdso32=1: enable 32-bit VDSO + vdso32=0 or vdso32=2: disable 32-bit VDSO + + See the help text for CONFIG_COMPAT_VDSO for more + details. If CONFIG_COMPAT_VDSO is set, the default is + vdso32=0; otherwise, the default is vdso32=1. + + For compatibility with older kernels, vdso32=2 is an + alias for vdso32=0. + + Try vdso32=0 if you encounter an error that says: + dl_main: Assertion `(void *) ph->p_vaddr == _rtld_local._dl_sysinfo_dso' failed! vector= [IA-64,SMP] vector=percpu: enable percpu vector domain @@ -3090,6 +3525,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. video= [FB] Frame buffer configuration See Documentation/fb/modedb.txt. + video.brightness_switch_enabled= [0,1] + If set to 1, on receiving an ACPI notify event + generated by hotkey, video driver will adjust brightness + level and then send out the event to user space through + the allocated input device; If set to 0, video driver + will only send out the event without touching backlight + brightness level. + default: 1 + virtio_mmio.device= [VMMIO] Memory mapped virtio (platform) device. @@ -3149,6 +3593,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. them quite hard to use for exploits but might break your system. + vt.color= [VT] Default text color. + Format: 0xYX, X = foreground, Y = background. + Default: 0x07 = light gray on black. + vt.cur_default= [VT] Default cursor shape. Format: 0xCCBBAA, where AA, BB, and CC are the same as the parameters of the <Esc>[?A;B;Cc escape sequence; @@ -3188,23 +3636,50 @@ bytes respectively. Such letter suffixes can also be entirely omitted. overridden by individual drivers. 0 will hide cursors, 1 will display them. + vt.italic= [VT] Default color for italic text; 0-15. + Default: 2 = green. + + vt.underline= [VT] Default color for underlined text; 0-15. + Default: 3 = cyan. + watchdog timers [HW,WDT] For information on watchdog timers, see Documentation/watchdog/watchdog-parameters.txt or other driver-specific files in the Documentation/watchdog/ directory. + workqueue.disable_numa + By default, all work items queued to unbound + workqueues are affine to the NUMA nodes they're + issued on, which results in better behavior in + general. If NUMA affinity needs to be disabled for + whatever reason, this option can be used. Note + that this also can be controlled per-workqueue for + workqueues visible under /sys/bus/workqueue/. + + workqueue.power_efficient + Per-cpu workqueues are generally preferred because + they show better performance thanks to cache + locality; unfortunately, per-cpu workqueues tend to + be more power hungry than unbound workqueues. + + Enabling this makes the per-cpu workqueues which + were observed to contribute significantly to power + consumption unbound, leading to measurably lower + power usage at the cost of small performance + overhead. + + The default value of this parameter is determined by + the config option CONFIG_WQ_POWER_EFFICIENT_DEFAULT. + x2apic_phys [X86-64,APIC] Use x2apic physical mode instead of default x2apic cluster mode on platforms supporting x2apic. - x86_mrst_timer= [X86-32,APBT] - Choose timer option for x86 Moorestown MID platform. + x86_intel_mid_timer= [X86-32,APBT] + Choose timer option for x86 Intel MID platform. Two valid options are apbt timer only and lapic timer plus one apbt timer for broadcast timer. - x86_mrst_timer=apbt_only | lapic_and_apbt - - xd= [HW,XT] Original XT pre-IDE (RLL encoded) disks. - xd_geo= See header of drivers/block/xd.c. + x86_intel_mid_timer=apbt_only | lapic_and_apbt xen_emul_unplug= [HW,X86,XEN] Unplug Xen emulated devices @@ -3218,6 +3693,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. the unplug protocol never -- do not unplug even if version check succeeds + xen_nopvspin [X86,XEN] + Disables the ticketlock slowpath using Xen PV + optimizations. + xirc2ps_cs= [NET,PCMCIA] Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]] |