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Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 126 |
1 files changed, 97 insertions, 29 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index a4f4d693e2c1..58f3c1041759 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -33,6 +33,37 @@ can also be entered as Double-quotes can be used to protect spaces in values, e.g.: param="spaces in here" +cpu lists: +---------- + +Some kernel parameters take a list of CPUs as a value, e.g. isolcpus, +nohz_full, irqaffinity, rcu_nocbs. The format of this list is: + + <cpu number>,...,<cpu number> + +or + + <cpu number>-<cpu number> + (must be a positive range in ascending order) + +or a mixture + +<cpu number>,...,<cpu number>-<cpu number> + +Note that for the special case of a range one can split the range into equal +sized groups and for each group use some amount from the beginning of that +group: + + <cpu number>-cpu number>:<used size>/<group size> + +For example one can add to the command line following parameter: + + isolcpus=1,2,10-20,100-2000:2/25 + +where the final item represents CPUs 100,101,125,126,150,151,... + + + 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 module. Loadable modules, after being loaded into the running kernel, also @@ -460,6 +491,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. driver will print ACPI tables for AMD IOMMU during IOMMU initialization. + amd_iommu_intr= [HW,X86-64] + Specifies one of the following AMD IOMMU interrupt + remapping modes: + legacy - Use legacy interrupt remapping mode. + vapic - Use virtual APIC mode, which allows IOMMU + to inject interrupts directly into guest. + This mode requires kvm-amd.avic=1. + (Default when IOMMU HW support is present.) + amijoy.map= [HW,JOY] Amiga joystick support Map of devices attached to JOY0DAT and JOY1DAT Format: <a>,<b> @@ -698,6 +738,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted. loops can be debugged more effectively on production systems. + clocksource.arm_arch_timer.fsl-a008585= + [ARM64] + Format: <bool> + Enable/disable the workaround of Freescale/NXP + erratum A-008585. This can be useful for KVM + guests, if the guest device tree doesn't show the + erratum. If unspecified, the workaround is + enabled based on the device tree. + clearcpuid=BITNUM [X86] Disable CPUID feature X for the kernel. See arch/x86/include/asm/cpufeatures.h for the valid bit @@ -1045,11 +1094,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. determined by the stdout-path property in device tree's chosen node. - cdns,<addr> - Start an early, polled-mode console on a cadence serial - port at the specified address. The cadence serial port - must already be setup and configured. Options are not - yet supported. + cdns,<addr>[,options] + Start an early, polled-mode console on a Cadence + (xuartps) serial port at the specified address. Only + supported option is baud rate. If baud rate is not + specified, the serial port must already be setup and + configured. uart[8250],io,<addr>[,options] uart[8250],mmio,<addr>[,options] @@ -1364,6 +1414,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: <unsigned int> such that (rxsize & ~0x1fffc0) == 0. Default: 1024 + gpio-mockup.gpio_mockup_ranges + [HW] Sets the ranges of gpiochip of for this device. + Format: <start1>,<end1>,<start2>,<end2>... + hardlockup_all_cpu_backtrace= [KNL] Should the hard-lockup detector generate backtraces on all cpus. @@ -1643,6 +1697,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. initrd= [BOOT] Specify the location of the initial ramdisk + init_pkru= [x86] Specify the default memory protection keys rights + register contents for all processes. 0x55555554 by + default (disallow access to all but pkey 0). Can + override in debugfs after boot. + inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver Format: <irq> @@ -1688,7 +1747,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. intel_idle.max_cstate= [KNL,HW,ACPI,X86] 0 disables intel_idle and fall back on acpi_idle. - 1 to 6 specify maximum depth of C-state. + 1 to 9 specify maximum depth of C-state. intel_pstate= [X86] disable @@ -1761,13 +1820,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See Documentation/filesystems/nfs/nfsroot.txt. irqaffinity= [SMP] Set the default irq affinity mask - Format: - <cpu number>,...,<cpu number> - or - <cpu number>-<cpu number> - (must be a positive range in ascending order) - or a mixture - <cpu number>,...,<cpu number>-<cpu number> + The argument is a cpu list, as described above. irqfixup [HW] When an interrupt is not handled search all handlers @@ -1784,13 +1837,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Format: <RDP>,<reset>,<pci_scan>,<verbosity> isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. - Format: - <cpu number>,...,<cpu number> - or - <cpu number>-<cpu number> - (must be a positive range in ascending order) - or a mixture - <cpu number>,...,<cpu number>-<cpu number> + The argument is a cpu list, as described above. This option can be used to specify one or more CPUs to isolate from the general SMP balancing and scheduling @@ -2161,10 +2208,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. than or equal to this physical address is ignored. maxcpus= [SMP] Maximum number of processors that an SMP kernel - should make use of. maxcpus=n : n >= 0 limits the - kernel to using 'n' processors. n=0 is a special case, - it is equivalent to "nosmp", which also disables - the IO APIC. + will bring up during bootup. maxcpus=n : n >= 0 limits + the kernel to bring up 'n' processors. Surely after + bootup you can bring up the other plugged cpu by executing + "echo 1 > /sys/devices/system/cpu/cpuX/online". So maxcpus + only takes effect during system bootup. + While n=0 is a special case, it is equivalent to "nosmp", + which also disables the IO APIC. max_loop= [LOOP] The number of loop block devices that get (loop.max_loop) unconditionally pre-created at init time. The default @@ -2420,6 +2470,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nfsrootdebug [NFS] enable nfsroot debugging messages. See Documentation/filesystems/nfs/nfsroot.txt. + nfs.callback_nr_threads= + [NFSv4] set the total number of threads that the + NFS client will assign to service NFSv4 callback + requests. + nfs.callback_tcpport= [NFS] set the TCP port on which the NFSv4 callback channel should listen. @@ -2443,6 +2498,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. of returning the full 64-bit number. The default is to return 64-bit inode numbers. + nfs.max_session_cb_slots= + [NFSv4.1] Sets the maximum number of session + slots the client will assign to the callback + channel. This determines the maximum number of + callbacks the client will process in parallel for + a particular server. + nfs.max_session_slots= [NFSv4.1] Sets the maximum number of session slots the client will attempt to negotiate with the server. @@ -2571,8 +2633,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nodelayacct [KNL] Disable per-task delay accounting - nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects. - nodsp [SH] Disable hardware DSP at boot time. noefi Disable EFI runtime services support. @@ -2651,6 +2711,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Default: on nohz_full= [KNL,BOOT] + The argument is a cpu list, as described above. 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 @@ -2773,9 +2834,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted. nr_cpus= [SMP] Maximum number of processors that an SMP kernel could support. nr_cpus=n : n >= 1 limits the kernel to - supporting 'n' processors. Later in runtime you can not - use hotplug cpu feature to put more cpu back to online. - just like you compile the kernel NR_CPUS=n + support 'n' processors. It could be larger than the + number of already plugged CPU during bootup, later in + runtime you can physically add extra cpu until it reaches + n. So during boot up some boot time memory for per-cpu + variables need be pre-allocated for later physical cpu + hot plugging. nr_uarts= [SERIAL] maximum number of UARTs to be registered. @@ -3253,6 +3317,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. See Documentation/blockdev/ramdisk.txt. rcu_nocbs= [KNL] + The argument is a cpu list, as described above. + 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 @@ -4238,6 +4304,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted. u = IGNORE_UAS (don't bind to the uas driver); w = NO_WP_DETECT (don't test whether the medium is write-protected). + y = ALWAYS_SYNC (issue a SYNCHRONIZE_CACHE + even if the device claims no cache) Example: quirks=0419:aaf5:rl,0421:0433:rc user_debug= [KNL,ARM] |