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Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 560 |
1 files changed, 355 insertions, 205 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3f1cc5e317ed..710b52d87bdd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -461,6 +461,12 @@ Format: <io>,<irq>,<mode> See header of drivers/net/hamradio/baycom_ser_hdx.c. + bert_disable [ACPI] + Disable BERT OS support on buggy BIOSes. + + bgrt_disable [ACPI][X86] + Disable BGRT to avoid flickering OEM logo. + blkdevparts= Manual partition parsing of block device(s) for embedded devices based on command line input. See Documentation/block/cmdline-partition.rst @@ -476,12 +482,6 @@ See Documentation/admin-guide/bootconfig.rst - 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. @@ -563,6 +563,25 @@ cio_ignore= [S390] See Documentation/s390/common_io.rst for details. + + clearcpuid=X[,X...] [X86] + Disable CPUID feature X for the kernel. See + arch/x86/include/asm/cpufeatures.h for the valid bit + numbers X. Note the Linux-specific bits are not necessarily + stable over kernel options, but the vendor-specific + ones should be. + X can also be a string as appearing in the flags: line + in /proc/cpuinfo which does not have the above + instability issue. However, not all features have names + in /proc/cpuinfo. + Note that using this option will taint your kernel. + Also note that user programs calling CPUID directly + or using the feature without checking anything + will still see it. This just prevents it from + being used by the kernel or shown in /proc/cpuinfo. + Also note the kernel might malfunction if you disable + some critical bits. + clk_ignore_unused [CLK] Prevents the clock framework from automatically gating @@ -631,19 +650,6 @@ Defaults to zero when built as a module and to 10 seconds when built into the kernel. - clearcpuid=BITNUM[,BITNUM...] [X86] - Disable CPUID feature X for the kernel. See - arch/x86/include/asm/cpufeatures.h for the valid bit - numbers. Note the Linux specific bits are not necessarily - stable over kernel options, but the vendor specific - ones should be. - Also note that user programs calling CPUID directly - or using the feature without checking anything - will still see it. This just prevents it from - being used by the kernel or shown in /proc/cpuinfo. - Also note the kernel might malfunction if you disable - some critical bits. - cma=nn[MG]@[start[MG][-end[MG]]] [KNL,CMA] Sets the size of kernel global memory area for @@ -765,6 +771,24 @@ 0: default value, disable debugging 1: enable debugging at boot time + cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver + Format: + <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + + cpu0_hotplug [X86] Turn on CPU0 hotplug feature when + CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. + Some features depend on CPU0. Known dependencies are: + 1. Resume from suspend/hibernate depends on CPU0. + Suspend/hibernate will fail if CPU0 is offline and you + need to online CPU0 before suspend/hibernate. + 2. PIC interrupts also depend on CPU0. CPU0 can't be + removed if a PIC interrupt is detected. + It's said poweroff/reboot may depend on CPU0 on some + machines although I haven't seen such issues so far + after CPU0 is offline on a few tested machines. + If the dependencies are under your control, you can + turn on cpu0_hotplug. + cpuidle.off=1 [CPU_IDLE] disable the cpuidle sub-system @@ -785,9 +809,13 @@ on every CPU online, such as boot, and resume from suspend. Default: 10000 - cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver - Format: - <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] + 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. crashkernel=size[KMG][@offset[KMG]] [KNL] Using kexec, Linux can switch to a 'crash kernel' @@ -808,7 +836,7 @@ Documentation/admin-guide/kdump/kdump.rst for an example. crashkernel=size[KMG],high - [KNL, X86-64] range could be above 4G. Allow kernel + [KNL, X86-64, ARM64] 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 @@ -821,14 +849,20 @@ that require some amount of low memory, e.g. swiotlb requires at least 64M+32K low memory, also enough extra low memory is needed to make sure DMA buffers for 32-bit - devices won't run out. Kernel would try to allocate at + devices won't run out. Kernel would try to allocate at least 256M below 4G automatically. - This one let user to specify own low range under 4G + This one lets the user 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. + [KNL, ARM64] range in low memory. + This one lets the user specify a low range in the + DMA zone for the crash dump kernel. + It will be ignored when crashkernel=X,high is not used + or memory reserved is located in the DMA zones. + cryptomgr.notests [KNL] Disable crypto self-tests @@ -950,6 +984,8 @@ dump out devices still on the deferred probe list after retrying. + delayacct [KNL] Enable per-task delay accounting + dell_smm_hwmon.ignore_dmi= [HW] Continue probing hardware even if DMI data indicates that the driver is running on unsupported @@ -1003,17 +1039,6 @@ disable= [IPV6] See Documentation/networking/ipv6.rst. - hardened_usercopy= - [KNL] Under CONFIG_HARDENED_USERCOPY, whether - hardening is enabled for this boot. Hardened - usercopy checking is used to protect the kernel - from reading or writing beyond known memory - allocation boundaries as a proactive defense - against bounds-checking flaws in the kernel's - copy_to_user()/copy_from_user() interface. - on Perform hardened usercopy checks (default). - off Disable hardened usercopy checks. - disable_radix [PPC] Disable RADIX MMU mode on POWER9 @@ -1282,7 +1307,7 @@ Append ",keep" to not disable it when the real console takes over. - Only one of vga, efi, serial, or usb debug port can + Only one of vga, serial, or usb debug port can be used at a time. Currently only ttyS0 and ttyS1 may be specified by @@ -1297,7 +1322,7 @@ Interaction with the standard serial driver is not very good. - The VGA and EFI output is eventually overwritten by + The VGA output is eventually overwritten by the real console. The xen option can only be used in Xen domains. @@ -1316,17 +1341,6 @@ force: enforce the use of EDAC to report H/W event. default: on. - ekgdboc= [X86,KGDB] Allow early kernel console debugging - ekgdboc=kbd - - This is designed to be used in conjunction with - the boot argument: earlyprintk=vga - - This parameter works in place of the kgdboc parameter - but can only be used if the backing tty is available - very early in the boot process. For early debugging - via a serial port see kgdboc_earlycon instead. - edd= [EDD] Format: {"off" | "on" | "skip[mbr]"} @@ -1388,6 +1402,17 @@ eisa_irq_edge= [PARISC,HW] See header of drivers/parisc/eisa.c. + ekgdboc= [X86,KGDB] Allow early kernel console debugging + Format: ekgdboc=kbd + + This is designed to be used in conjunction with + the boot argument: earlyprintk=vga + + This parameter works in place of the kgdboc parameter + but can only be used if the backing tty is available + very early in the boot process. For early debugging + via a serial port see kgdboc_earlycon instead. + elanfreq= [X86-32] See comment before function elanfreq_setup() in arch/x86/kernel/cpu/cpufreq/elanfreq.c. @@ -1586,6 +1611,17 @@ Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. Default: 1024 + hardened_usercopy= + [KNL] Under CONFIG_HARDENED_USERCOPY, whether + hardening is enabled for this boot. Hardened + usercopy checking is used to protect the kernel + from reading or writing beyond known memory + allocation boundaries as a proactive defense + against bounds-checking flaws in the kernel's + copy_to_user()/copy_from_user() interface. + on Perform hardened usercopy checks (default). + off Disable hardened usercopy checks. + hardlockup_all_cpu_backtrace= [KNL] Should the hard-lockup detector generate backtraces on all cpus. @@ -1606,6 +1642,15 @@ corresponding firmware-first mode error processing logic will be disabled. + hibernate= [HIBERNATION] + 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. + protect_image Turn on image protection during restoration + (that will set all pages holding image data + during restoration read-only). + highmem=nn[KMG] [KNL,BOOT] forces the highmem zone to have an exact size of <nn>. This works even on boxes that have no highmem otherwise. This also works to reduce highmem @@ -1628,16 +1673,6 @@ hpet_mmap= [X86, HPET_MMAP] Allow userspace to mmap HPET registers. Default set by CONFIG_HPET_MMAP_DEFAULT. - hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation - of gigantic hugepages. Or using node format, the size - of a CMA area per node can be specified. - Format: nn[KMGTPE] or (node format) - <node>:nn[KMGTPE][,<node>: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] Number of HugeTLB pages to allocate at boot. If this follows hugepagesz (below), it specifies the number of pages of hugepagesz to be allocated. @@ -1659,17 +1694,27 @@ Documentation/admin-guide/mm/hugetlbpage.rst. Format: size[KMG] + hugetlb_cma= [HW,CMA] The size of a CMA area used for allocation + of gigantic hugepages. Or using node format, the size + of a CMA area per node can be specified. + Format: nn[KMGTPE] or (node format) + <node>:nn[KMGTPE][,<node>: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. + hugetlb_free_vmemmap= - [KNL] Reguires CONFIG_HUGETLB_PAGE_FREE_VMEMMAP + [KNL] Reguires CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP enabled. Allows heavy hugetlb users to free up some more memory (7 * PAGE_SIZE for each 2MB hugetlb page). - Format: { on | off (default) } + Format: { [oO][Nn]/Y/y/1 | [oO][Ff]/N/n/0 (default) } - on: enable the feature - off: disable the feature + [oO][Nn]/Y/y/1: enable the feature + [oO][Ff]/N/n/0: disable the feature - Built with CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON=y, + Built with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=y, the default is on. This is not compatible with memory_hotplug.memmap_on_memory. @@ -1758,26 +1803,6 @@ icn= [HW,ISDN] Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]] - ide-core.nodma= [HW] (E)IDE subsystem - 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.rst. - - ide-generic.probe-mask= [HW] (E)IDE subsystem - Format: <int> - Probe mask for legacy ISA IDE ports. Depending on - platform up to 6 ports are supported, enabled by - setting corresponding bits in the mask to 1. The - default value is 0x0, which has a special meaning. - On systems that have PCI, it triggers scanning the - PCI bus for the first and the second port, which - are then probed. On systems without PCI the value - of 0x0 enables probing the two first ports as if it - was 0x3. - - ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem - Claim all unknown PCI IDE storage controllers. idle= [X86] Format: idle=poll, idle=halt, idle=nomwait @@ -1903,7 +1928,8 @@ ima_template= [IMA] Select one of defined IMA measurements template formats. - Formats: { "ima" | "ima-ng" | "ima-sig" } + Formats: { "ima" | "ima-ng" | "ima-ngv2" | "ima-sig" | + "ima-sigv2" } Default: "ima-ng" ima_template_fmt= @@ -2622,14 +2648,14 @@ when set. Format: <int> - libata.force= [LIBATA] Force configurations. The format is comma- - separated list of "[ID:]VAL" where ID is - PORT[.DEVICE]. PORT and DEVICE are decimal numbers - matching port, link or device. Basically, it matches - the ATA ID string printed on console by libata. If - the whole ID part is omitted, the last PORT and DEVICE - values are used. If ID hasn't been specified yet, the - configuration applies to all ports, links and devices. + libata.force= [LIBATA] Force configurations. The format is a comma- + separated list of "[ID:]VAL" where ID is PORT[.DEVICE]. + PORT and DEVICE are decimal numbers matching port, link + or device. Basically, it matches the ATA ID string + printed on console by libata. If the whole ID part is + omitted, the last PORT and DEVICE values are used. If + ID hasn't been specified yet, the configuration applies + to all ports, links and devices. If only DEVICE is omitted, the parameter applies to the port and all links and devices behind it. DEVICE @@ -2639,7 +2665,7 @@ host link and device attached to it. The VAL specifies the configuration to force. As long - as there's no ambiguity shortcut notation is allowed. + as there is no ambiguity, shortcut notation is allowed. For example, both 1.5 and 1.5G would work for 1.5Gbps. The following configurations can be forced. @@ -2652,27 +2678,64 @@ udma[/][16,25,33,44,66,100,133] notation is also allowed. + * nohrst, nosrst, norst: suppress hard, soft and both + resets. + + * rstonce: only attempt one reset during hot-unplug + link recovery. + + * [no]dbdelay: Enable or disable the extra 200ms delay + before debouncing a link PHY and device presence + detection. + * [no]ncq: Turn on or off NCQ. - * [no]ncqtrim: Turn off queued DSM TRIM. + * [no]ncqtrim: Enable or disable queued DSM TRIM. + + * [no]ncqati: Enable or disable NCQ trim on ATI chipset. + + * [no]trim: Enable or disable (unqueued) TRIM. + + * trim_zero: Indicate that TRIM command zeroes data. + + * max_trim_128m: Set 128M maximum trim size limit. + + * [no]dma: Turn on or off DMA transfers. - * nohrst, nosrst, norst: suppress hard, soft - and both resets. + * atapi_dmadir: Enable ATAPI DMADIR bridge support. - * rstonce: only attempt one reset during - hot-unplug link recovery + * atapi_mod16_dma: Enable the use of ATAPI DMA for + commands that are not a multiple of 16 bytes. - * dump_id: dump IDENTIFY data. + * [no]dmalog: Enable or disable the use of the + READ LOG DMA EXT command to access logs. - * atapi_dmadir: Enable ATAPI DMADIR bridge support + * [no]iddevlog: Enable or disable access to the + identify device data log. + + * [no]logdir: Enable or disable access to the general + purpose log directory. + + * max_sec_128: Set transfer size limit to 128 sectors. + + * max_sec_1024: Set or clear transfer size limit to + 1024 sectors. + + * max_sec_lba48: Set or clear transfer size limit to + 65535 sectors. + + * [no]lpm: Enable or disable link power management. + + * [no]setxfer: Indicate if transfer speed mode setting + should be skipped. + + * dump_id: Dump IDENTIFY data. * disable: Disable this device. If there are multiple matching configurations changing the same attribute, the last one is used. - memblock=debug [KNL] Enable memblock debug messages. - load_ramdisk= [RAM] [Deprecated] lockd.nlm_grace_period=P [NFS] Assign grace period. @@ -2814,7 +2877,7 @@ different yeeloong laptops. Example: machtype=lemote-yeeloong-2f-7inch - max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater + max_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory greater than or equal to this physical address is ignored. maxcpus= [SMP] Maximum number of processors that an SMP kernel @@ -2914,6 +2977,8 @@ mem=nopentium [BUGS=X86-32] Disable usage of 4MB pages for kernel memory. + memblock=debug [KNL] Enable memblock debug messages. + memchunk=nn[KMG] [KNL,SH] Allow user to override the default size for per-device physically contiguous DMA buffers. @@ -3057,7 +3122,7 @@ mga= [HW,DRM] - min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this + min_addr=nn[KMG] [KNL,BOOT,IA-64] All physical memory below this physical address is ignored. mini2440= [ARM,HW,KNL] @@ -3103,6 +3168,7 @@ mds=off [X86] tsx_async_abort=off [X86] kvm.nx_huge_pages=off [X86] + srbds=off [X86,INTEL] no_entry_flush [PPC] no_uaccess_flush [PPC] @@ -3181,20 +3247,6 @@ mtdparts= [MTD] See drivers/mtd/parsers/cmdlinepart.c - multitce=off [PPC] This parameter disables the use of the pSeries - firmware feature for updating multiple TCE entries - at a time. - - onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration - - Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] - - boundary - index of last SLC block on Flex-OneNAND. - The remaining blocks are configured as MLC blocks. - lock - Configure if Flex-OneNAND boundary should be locked. - Once locked, the boundary cannot be changed. - 1 indicates lock status, 0 indicates unlock status. - mtdset= [ARM] ARM/S3C2412 JIVE boot control @@ -3221,6 +3273,10 @@ Used for mtrr cleanup. It is spare mtrr entries number. Set to 2 or more if your graphical card needs more. + multitce=off [PPC] This parameter disables the use of the pSeries + firmware feature for updating multiple TCE entries + at a time. + n2= [NET] SDL Inc. RISCom/N2 synchronous serial card netdev= [NET] Network devices parameters @@ -3230,6 +3286,11 @@ This usage is only documented in each driver source file if at all. + netpoll.carrier_timeout= + [NET] Specifies amount of time (in seconds) that + netpoll should wait for a carrier. By default netpoll + waits 4 seconds. + nf_conntrack.acct= [NETFILTER] Enable connection tracking flow accounting 0 to disable accounting @@ -3380,11 +3441,6 @@ These settings can be accessed at runtime via the nmi_watchdog and hardlockup_panic sysctls. - netpoll.carrier_timeout= - [NET] Specifies amount of time (in seconds) that - netpoll should wait for a carrier. By default netpoll - waits 4 seconds. - no387 [BUGS=X86-32] Tells the kernel to use the 387 maths emulation library even if a 387 maths coprocessor is present. @@ -3439,10 +3495,6 @@ nocache [ARM] - noclflush [BUGS=X86] Don't use the CLFLUSH instruction - - delayacct [KNL] Enable per-task delay accounting - nodsp [SH] Disable hardware DSP at boot time. noefi Disable EFI runtime services support. @@ -3451,16 +3503,11 @@ noexec [IA-64] - noexec [X86] - On X86-32 available only on PAE configured kernels. - noexec=on: enable non-executable mappings (default) - noexec=off: disable non-executable mappings - - nosmap [X86,PPC] + nosmap [PPC] Disable SMAP (Supervisor Mode Access Prevention) even if it is supported by processor. - nosmep [X86,PPC64s] + nosmep [PPC64s] Disable SMEP (Supervisor Mode Execution Prevention) even if it is supported by processor. @@ -3660,8 +3707,6 @@ nosbagart [IA-64] - nosep [BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support. - nosgx [X86-64,SGX] Disables Intel SGX kernel support. nosmp [SMP] Tells an SMP kernel to act as a UP kernel, @@ -3678,20 +3723,6 @@ nox2apic [X86-64,APIC] Do not enable x2APIC mode. - cpu0_hotplug [X86] Turn on CPU0 hotplug feature when - CONFIG_BOOTPARAM_HOTPLUG_CPU0 is off. - Some features depend on CPU0. Known dependencies are: - 1. Resume from suspend/hibernate depends on CPU0. - Suspend/hibernate will fail if CPU0 is offline and you - need to online CPU0 before suspend/hibernate. - 2. PIC interrupts also depend on CPU0. CPU0 can't be - removed if a PIC interrupt is detected. - It's said poweroff/reboot may depend on CPU0 on some - machines although I haven't seen such issues so far - after CPU0 is offline on a few tested machines. - If the dependencies are under your control, you can - turn on cpu0_hotplug. - nps_mtm_hs_ctr= [KNL,ARC] This parameter sets the maximum duration, in cycles, each HW thread of the CTOP can run @@ -3744,6 +3775,16 @@ For example, to override I2C bus2: omap_mux=i2c2_scl.i2c2_scl=0x100,i2c2_sda.i2c2_sda=0x100 + onenand.bdry= [HW,MTD] Flex-OneNAND Boundary Configuration + + Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock] + + boundary - index of last SLC block on Flex-OneNAND. + The remaining blocks are configured as MLC blocks. + lock - Configure if Flex-OneNAND boundary should be locked. + Once locked, the boundary cannot be changed. + 1 indicates lock status, 0 indicates unlock status. + oops=panic Always panic on oopses. Default is to just kill the process, but there is a small probability of deadlocking the machine. @@ -3814,14 +3855,6 @@ panic_on_warn panic() instead of WARN(). Useful to cause kdump on a WARN(). - 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#> @@ -4066,6 +4099,15 @@ please report a bug. nocrs [X86] Ignore PCI host bridge windows from ACPI. If you need to use this, please report a bug. + use_e820 [X86] Use E820 reservations to exclude parts of + PCI host bridge windows. This is a workaround + for BIOS defects in host bridge _CRS methods. + If you need to use this, please report a bug to + <linux-pci@vger.kernel.org>. + no_e820 [X86] Ignore E820 reservations for PCI host + bridge windows. This is the default on modern + hardware. If you need to use this, please report + a bug to <linux-pci@vger.kernel.org>. routeirq Do IRQ routing for all PCI devices. This is normally done in pci_enable_device(), so this option is a temporary workaround @@ -4893,6 +4935,18 @@ rcupdate.rcu_cpu_stall_timeout= [KNL] Set timeout for RCU CPU stall warning messages. + The value is in seconds and the maximum allowed + value is 300 seconds. + + rcupdate.rcu_exp_cpu_stall_timeout= [KNL] + Set timeout for expedited RCU CPU stall warning + messages. The value is in milliseconds + and the maximum allowed value is 21000 + milliseconds. Please note that this value is + adjusted to an arch timer tick resolution. + Setting this to zero causes the value from + rcupdate.rcu_cpu_stall_timeout to be used (after + conversion from seconds to milliseconds). rcupdate.rcu_expedited= [KNL] Use expedited grace-period primitives, for @@ -4955,10 +5009,34 @@ number avoids disturbing real-time workloads, but lengthens grace periods. + rcupdate.rcu_task_stall_info= [KNL] + Set initial timeout in jiffies for RCU task stall + informational messages, which give some indication + of the problem for those not patient enough to + wait for ten minutes. Informational messages are + only printed prior to the stall-warning message + for a given grace period. Disable with a value + less than or equal to zero. Defaults to ten + seconds. A change in value does not take effect + until the beginning of the next grace period. + + rcupdate.rcu_task_stall_info_mult= [KNL] + Multiplier for time interval between successive + RCU task stall informational messages for a given + RCU tasks grace period. This value is clamped + to one through ten, inclusive. It defaults to + the value three, so that the first informational + message is printed 10 seconds into the grace + period, the second at 40 seconds, the third at + 160 seconds, and then the stall warning at 600 + seconds would prevent a fourth at 640 seconds. + rcupdate.rcu_task_stall_timeout= [KNL] - Set timeout in jiffies for RCU task stall warning - messages. Disable with a value less than or equal - to zero. + Set timeout in jiffies for RCU task stall + warning messages. Disable with a value less + than or equal to zero. Defaults to ten minutes. + A change in value does not take effect until + the beginning of the next grace period. rcupdate.rcu_self_test= [KNL] Run the RCU early boot self tests @@ -5077,15 +5155,6 @@ Useful for devices that are detected asynchronously (e.g. USB and MMC devices). - hibernate= [HIBERNATION] - 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. - protect_image Turn on image protection during restoration - (that will set all pages holding image data - during restoration read-only). - retain_initrd [RAM] Keep initrd memory after extraction rfkill.default_state= @@ -5308,6 +5377,8 @@ serialnumber [BUGS=X86-32] + sev=option[,option...] [X86-64] See Documentation/x86/x86_64/boot-options.rst + shapers= [NET] Maximal number of shapers. @@ -5377,6 +5448,17 @@ smart2= [HW] Format: <io1>[,<io2>[,...,<io8>]] + smp.csd_lock_timeout= [KNL] + Specify the period of time in milliseconds + that smp_call_function() and friends will wait + for a CPU to release the CSD lock. This is + useful when diagnosing bugs involving CPUs + disabling interrupts for extended periods + of time. Defaults to 5,000 milliseconds, and + setting a value of zero disables this feature. + This feature may be more efficiently disabled + using the csdlock_debug- kernel parameter. + smsc-ircc2.nopnp [HW] Don't use PNP to discover SMC devices smsc-ircc2.ircc_cfg= [HW] Device configuration I/O port smsc-ircc2.ircc_sir= [HW] SIR base I/O port @@ -5388,7 +5470,7 @@ 1: Fast pin select (default) 2: ATC IRMode - smt [KNL,S390] Set the maximum number of threads (logical + smt= [KNL,S390] Set the maximum number of threads (logical CPUs) to use per physical CPU on systems capable of symmetric multithreading (SMT). Will be capped to the actual hardware limit. @@ -5608,6 +5690,30 @@ off: Disable mitigation and remove performance impact to RDRAND and RDSEED + srcutree.big_cpu_lim [KNL] + Specifies the number of CPUs constituting a + large system, such that srcu_struct structures + should immediately allocate an srcu_node array. + This kernel-boot parameter defaults to 128, + but takes effect only when the low-order four + bits of srcutree.convert_to_big is equal to 3 + (decide at boot). + + srcutree.convert_to_big [KNL] + Specifies under what conditions an SRCU tree + srcu_struct structure will be converted to big + form, that is, with an rcu_node tree: + + 0: Never. + 1: At init_srcu_struct() time. + 2: When rcutorture decides to. + 3: Decide at boot time (default). + 0x1X: Above plus if high contention. + + Either way, the srcu_node tree will be sized based + on the actual runtime number of CPUs (nr_cpu_ids) + instead of the compile-time CONFIG_NR_CPUS. + srcutree.counter_wrap_check [KNL] Specifies how frequently to check for grace-period sequence counter wrap for the @@ -5625,6 +5731,14 @@ expediting. Set to zero to disable automatic expediting. + srcutree.small_contention_lim [KNL] + Specifies the number of update-side contention + events per jiffy will be tolerated before + initiating a conversion of an srcu_struct + structure to big form. Note that the value of + srcutree.convert_to_big must have the 0x10 bit + set for contention-based conversions to occur. + ssbd= [ARM64,HW] Speculative Store Bypass Disable control @@ -5743,8 +5857,9 @@ This parameter controls use of the Protected Execution Facility on pSeries. - swapaccount=[0|1] - [KNL] Enable accounting of swap in memory resource + swapaccount= [KNL] + Format: [0|1] + Enable accounting of swap in memory resource controller if no parameter or 1 is given or disable it if 0 is given (See Documentation/admin-guide/cgroup-v1/memory.rst) @@ -5790,7 +5905,8 @@ tdfx= [HW,DRM] - test_suspend= [SUSPEND][,N] + test_suspend= [SUSPEND] + Format: { "mem" | "standby" | "freeze" }[,N] Specify "mem" (for Suspend-to-RAM) or "standby" (for standby suspend) or "freeze" (for suspend type freeze) as the system sleep state during system startup with @@ -5874,32 +5990,7 @@ This will guarantee that all the other pcrs are saved. - trace_buf_size=nn[KMG] - [FTRACE] will set tracing buffer size on each cpu. - - trace_event=[event-list] - [FTRACE] Set and start specified trace events in order - to facilitate early boot debugging. The event-list is a - comma-separated list of trace events to enable. See - also Documentation/trace/events.rst - - trace_options=[option-list] - [FTRACE] Enable or disable tracer options at boot. - The option-list is a comma delimited list of options - that can be enabled or disabled just as if you were - to echo the option name into - - /sys/kernel/debug/tracing/trace_options - - For example, to enable stacktrace option (to dump the - stack trace of each event), add to the command line: - - trace_options=stacktrace - - See also Documentation/trace/ftrace.rst "trace options" - section. - - tp_printk[FTRACE] + tp_printk [FTRACE] Have the tracepoints sent to printk as well as the tracing ring buffer. This is useful for early boot up where the system hangs or reboots and does not give the @@ -5921,7 +6012,7 @@ frequency tracepoints such as irq or sched, can cause the system to live lock. - tp_printk_stop_on_boot[FTRACE] + tp_printk_stop_on_boot [FTRACE] When tp_printk (above) is set, it can cause a lot of noise on the console. It may be useful to only include the printing of events during boot up, as user space may @@ -5930,6 +6021,53 @@ This command line option will stop the printing of events to console at the late_initcall_sync() time frame. + trace_buf_size=nn[KMG] + [FTRACE] will set tracing buffer size on each cpu. + + trace_clock= [FTRACE] Set the clock used for tracing events + at boot up. + local - Use the per CPU time stamp counter + (converted into nanoseconds). Fast, but + depending on the architecture, may not be + in sync between CPUs. + global - Event time stamps are synchronize across + CPUs. May be slower than the local clock, + but better for some race conditions. + counter - Simple counting of events (1, 2, ..) + note, some counts may be skipped due to the + infrastructure grabbing the clock more than + once per event. + uptime - Use jiffies as the time stamp. + perf - Use the same clock that perf uses. + mono - Use ktime_get_mono_fast_ns() for time stamps. + mono_raw - Use ktime_get_raw_fast_ns() for time + stamps. + boot - Use ktime_get_boot_fast_ns() for time stamps. + Architectures may add more clocks. See + Documentation/trace/ftrace.rst for more details. + + trace_event=[event-list] + [FTRACE] Set and start specified trace events in order + to facilitate early boot debugging. The event-list is a + comma-separated list of trace events to enable. See + also Documentation/trace/events.rst + + trace_options=[option-list] + [FTRACE] Enable or disable tracer options at boot. + The option-list is a comma delimited list of options + that can be enabled or disabled just as if you were + to echo the option name into + + /sys/kernel/debug/tracing/trace_options + + For example, to enable stacktrace option (to dump the + stack trace of each event), add to the command line: + + trace_options=stacktrace + + See also Documentation/trace/ftrace.rst "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 @@ -5958,11 +6096,22 @@ sources: - "tpm" - "tee" + - "caam" If not specified then it defaults to iterating through the trust source list starting with TPM and assigns the first trust source as a backend which is initialized successfully during iteration. + trusted.rng= [KEYS] + Format: <string> + The RNG used to generate key material for trusted keys. + Can be one of: + - "kernel" + - the same value as trusted.source: "tpm" or "tee" + - "default" + If not specified, "default" is used. In this case, + the RNG's choice is left to each individual trust source. + tsc= Disable clocksource stability checks for TSC. Format: <string> [x86] reliable: mark tsc clocksource as reliable, this @@ -6270,7 +6419,7 @@ HIGHMEM regardless of setting of CONFIG_HIGHPTE. - vdso= [X86,SH] + vdso= [X86,SH,SPARC] On X86_32, this is an alias for vdso32=. Otherwise: vdso=1: enable VDSO (the default) @@ -6296,11 +6445,12 @@ video= [FB] Frame buffer configuration See Documentation/fb/modedb.rst. - video.brightness_switch_enabled= [0,1] + video.brightness_switch_enabled= [ACPI] + Format: [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 + the allocated input device. If set to 0, video driver will only send out the event without touching backlight brightness level. default: 1 |