usbcore.blinkenlights=1
+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
+
+
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
EFI EFI Partitioning (GPT) is enabled
EIDE EIDE/ATAPI support is enabled.
FB The frame buffer device is enabled.
+ GCOV GCOV profiling is enabled.
HW Appropriate hardware is enabled.
IA-64 IA-64 architecture is enabled.
IMA Integrity measurement architecture is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
- KMEMTRACE kmemtrace is enabled.
+ KVM Kernel Virtual Machine support is enabled.
LIBATA Libata driver is enabled
LP Printer support is enabled.
LOOP Loopback device support is enabled.
./include/asm/setup.h as COMMAND_LINE_SIZE.
- acpi= [HW,ACPI,X86-64,i386]
+ acpi= [HW,ACPI,X86]
Advanced Configuration and Power Interface
Format: { force | off | ht | strict | noirq | rsdt }
force -- enable ACPI if default was off
acpi_osi="!string2" # remove built-in string2
acpi_osi= # disable all strings
- acpi_pm_good [X86-32,X86-64]
+ acpi_pm_good [X86]
Override the pmtimer bug detection: force the kernel
to assume that this machine's pmtimer latches its value
and always returns good values.
- acpi.power_nocheck= [HW,ACPI]
- Format: 1/0 enable/disable the check of power state.
- On some bogus BIOS the _PSC object/_STA object of
- power resource can't return the correct device power
- state. In such case it is unneccessary to check its
- power state again in power transition.
- 1 : disable the power state check
+ 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.
+
+ acpi_sleep= [HW,ACPI] Sleep options
+ Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
+ old_ordering, s4_nonvs }
+ See Documentation/power/video.txt for information on
+ s3_bios and s3_mode.
+ s3_beep is for debugging; it makes the PC's speaker beep
+ as soon as the kernel's real-mode entry point is called.
+ s4_nohwsig prevents ACPI hardware signature from being
+ used during resume from hibernation.
+ old_ordering causes the ACPI 1.0 ordering of the _PTS
+ control method, with respect to putting devices into
+ low power states, to be enforced (the ACPI 2.0 ordering
+ of _PTS is used by default).
+ s4_nonvs prevents the kernel from saving/restoring the
+ ACPI NVS memory during hibernation.
+
+ acpi_use_timer_override [HW,ACPI]
+ Use timer override. For some broken Nvidia NF5 boards
+ that require a timer override, but don't have HPET
acpi_enforce_resources= [ACPI]
{ strict | lax | no }
ad1848= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<type>
+ add_efi_memmap [EFI; X86] Include EFI memory map in
+ kernel's map of available physical RAM.
+
advansys= [HW,SCSI]
See header of drivers/scsi/advansys.c.
flushed before they will be reused, which
is a lot of faster
- amd_iommu_size= [HW,X86-64]
- Define the size of the aperture for the AMD IOMMU
- driver. Possible values are:
- '32M', '64M' (default), '128M', '256M', '512M', '1G'
-
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: <a>,<b>
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
- apic= [APIC,i386] Advanced Programmable Interrupt Controller
+ apic= [APIC,X86-32] Advanced Programmable Interrupt Controller
Change the output verbosity whilst booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
Also note the kernel might malfunction if you disable
some critical bits.
- code_bytes [IA32/X86_64] How many bytes of object code to print
+ cmo_free_hint= [PPC] Format: { yes | no }
+ Specify whether pages are marked as being inactive
+ when they are freed. This is used in CMO environments
+ to determine OS memory pressure for page stealing by
+ a hypervisor.
+ Default: yes
+
+ code_bytes [X86] How many bytes of object code to print
in an oops report.
Range: 0 - 8192
Default: 64
console=brl,ttyS0
For now, only VisioBraille is supported.
+ consoleblank= [KNL] The console blank (screen saver) timeout in
+ seconds. Defaults to 10*60 = 10mins. A value of 0
+ disables the blank timer.
+
coredump_filter=
[KNL] Change the default value for
/proc/<pid>/coredump_filter.
MTRR settings. This parameter disables that behavior,
possibly causing your machine to run very slowly.
- disable_timer_pin_1 [i386,x86-64]
+ disable_timer_pin_1 [X86]
Disable PIN 1 of APIC timer
Can be useful to work around chipset bugs.
DMA-API debugging code disables itself because the
architectural default is too low.
+ dma_debug_driver=<driver_name>
+ With this option the DMA-API debugging driver
+ filter feature can be enabled at boot time. Just
+ pass the driver to filter for as the parameter.
+ The filter can be disabled or changed to another
+ driver later using sysfs.
+
dscc4.setup= [NET]
dtc3181e= [HW,SCSI]
UART at the specified I/O port or MMIO address.
The options are the same as for ttyS, above.
- earlyprintk= [X86-32,X86-64,SH,BLACKFIN]
+ earlyprintk= [X86,SH,BLACKFIN]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]
- earlyprintk=dbgp
+ earlyprintk=dbgp[debugController#]
Append ",keep" to not disable it when the real console
takes over.
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
- elfcorehdr= [IA64,PPC,SH,X86-32,X86_64]
+ elfcorehdr= [IA64,PPC,SH,X86]
Specifies physical address of start of kernel core
image elf header. Generally kexec loader will
pass this option to capture kernel.
to discrete, to make X server driver able to add WB
entry later. This parameter enables that.
- enable_timer_pin_1 [i386,x86-64]
+ enable_timer_pin_1 [X86]
Enable PIN 1 of APIC timer
Can be useful to work around chipset bugs
(in particular on some ATI chipsets).
ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
ftrace=[tracer]
- [ftrace] will set and start the specified tracer
+ [FTRACE] will set and start the specified tracer
as early as possible in order to facilitate early
boot debugging.
ftrace_dump_on_oops
- [ftrace] will dump the trace buffers on oops.
+ [FTRACE] will dump the trace buffers on oops.
+
+ ftrace_filter=[function-list]
+ [FTRACE] Limit the functions traced by the function
+ tracer at boot up. function-list is a comma separated
+ list of functions. This list can be changed at run
+ time by the set_ftrace_filter file in the debugfs
+ tracing directory.
+
+ ftrace_notrace=[function-list]
+ [FTRACE] Do not trace the functions specified in
+ function-list. This list can be changed at run time
+ by the set_ftrace_notrace file in the debugfs
+ tracing directory.
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
Format: off | on
default: on
+ gcov_persist= [GCOV] When non-zero (default), profiling data for
+ kernel modules is saved and remains accessible via
+ debugfs, even when the module is unloaded/reloaded.
+ When zero, profiling data is discarded and associated
+ debugfs files are removed at module unload time.
+
gdth= [HW,SCSI]
See header of drivers/scsi/gdth.c.
hashdist= [KNL,NUMA] Large hashes allocated during boot
are distributed across NUMA nodes. Defaults on
- for IA-64, off otherwise.
+ for 64bit NUMA, off otherwise.
Format: 0 | 1 (for off | on)
hcl= [IA-64] SGI's Hardware Graph compatibility layer
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 .noprobe .nowerr .cdrom
- .chs .ignore_cable are additional options
- See Documentation/ide/ide.txt.
-
- idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
+ .vlb_clock .pci_clock .noflush .nohpa .noprobe .nowerr
+ .cdrom .chs .ignore_cable are additional options
See Documentation/ide/ide.txt.
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
1 -- enable informational integrity auditing messages.
ima_hash= [IMA]
- Formt: { "sha1" | "md5" }
+ Format: { "sha1" | "md5" }
default: "sha1"
+ 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.
+
in2000= [HW,SCSI]
See header of drivers/scsi/in2000.c.
nomerge
forcesac
soft
+ pt [x86, IA64]
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
arch/alpha/kernel/core_marvel.c.
- io_delay= [X86-32,X86-64] I/O delay method
+ io_delay= [X86] I/O delay method
0x80
Standard port 0x80 based delay
0xed
keepinitrd [HW,ARM]
- kernelcore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
+ kernelcore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
specifies the amount of memory usable by the kernel
for non-movable allocations. The requested amount is
spread evenly throughout all nodes in the system. The
use the HighMem zone if it exists, and the Normal
zone if it does not.
- kmemtrace.enable= [KNL,KMEMTRACE] Format: { yes | no }
- Controls whether kmemtrace is enabled
- at boot-time.
-
- kmemtrace.subbufs=n [KNL,KMEMTRACE] Overrides the number of
- subbufs kmemtrace's relay channel has. Set this
- higher than default (KMEMTRACE_N_SUBBUFS in code) if
- you experience buffer overruns.
-
kgdboc= [HW] kgdb over consoles.
Requires a tty driver that supports console polling.
- (only serial suported for now)
+ (only serial supported for now)
Format: <serial_device>[,baud]
kmac= [MIPS] korina ethernet MAC address.
Configure the RouterBoard 532 series on-chip
Ethernet adapter MAC address.
- kstack=N [X86-32,X86-64] Print N words from the kernel stack
+ kmemleak= [KNL] Boot-time kmemleak enable/disable
+ Valid arguments: on, off
+ Default: on
+
+ kstack=N [X86] Print N words from the kernel stack
in oops dumps.
+ kvm.ignore_msrs=[KVM] Ignore guest accesses to unhandled MSRs.
+ Default is 0 (don't ignore, but inject #GP)
+
+ kvm.oos_shadow= [KVM] Disable out-of-sync shadow paging.
+ Default is 1 (enabled)
+
+ kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
+ Default is 0 (off)
+
+ kvm-amd.npt= [KVM,AMD] Disable nested paging (virtualized MMU)
+ for all guests.
+ Default is 1 (enabled) if in 64bit or 32bit-PAE mode
+
+ kvm-intel.bypass_guest_pf=
+ [KVM,Intel] Disables bypassing of guest page faults
+ on Intel chips. Default is 1 (enabled)
+
+ kvm-intel.ept= [KVM,Intel] Disable extended page tables
+ (virtualized MMU) support on capable Intel chips.
+ Default is 1 (enabled)
+
+ kvm-intel.emulate_invalid_guest_state=
+ [KVM,Intel] Enable emulation of invalid guest states
+ Default is 0 (disabled)
+
+ kvm-intel.flexpriority=
+ [KVM,Intel] Disable FlexPriority feature (TPR shadow).
+ Default is 1 (enabled)
+
+ kvm-intel.unrestricted_guest=
+ [KVM,Intel] Disable unrestricted guest feature
+ (virtualized real and unpaged mode) on capable
+ Intel chips. Default is 1 (enabled)
+
+ kvm-intel.vpid= [KVM,Intel] Disable Virtual Processor Identification
+ feature (tagged TLBs) on capable Intel chips.
+ Default is 1 (enabled)
+
l2cr= [PPC]
l3cr= [PPC]
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
- lapic_timer_c2_ok [X86-32,x86-64,APIC] trust the local apic timer
+ lapic_timer_c2_ok [X86,APIC] trust the local apic timer
in C2 power state.
libata.dma= [LIBATA] DMA control
libata.dma=4 Compact Flash DMA only
Combinations also work, so libata.dma=3 enables DMA
for disks and CDROMs, but not CFs.
+
+ libata.ignore_hpa= [LIBATA] Ignore HPA limit
+ libata.ignore_hpa=0 keep BIOS limits (default)
+ libata.ignore_hpa=1 ignore limits, using full disk
libata.noacpi [LIBATA] Disables use of ACPI in libata suspend/resume
when set.
(machvec) in a generic kernel.
Example: machvec=hpzx1_swiotlb
+ machtype= [Loongson] Share the same kernel image file between different
+ yeeloong laptop.
+ Example: machtype=lemote-yeeloong-2f-7inch
+
max_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory greater
than or equal to this physical address is ignored.
[KNL,SH] Allow user to override the default size for
per-device physically contiguous DMA buffers.
- memmap=exactmap [KNL,X86-32,X86_64] Enable setting of an exact
+ memmap=exactmap [KNL,X86] Enable setting of an exact
E820 memory map, as specified by the user.
Such memmap=exactmap lines can be constructed based on
BIOS output or other requirements. See the memmap=nn@ss
min_addr=nn[KMG] [KNL,BOOT,ia64] All physical memory below this
physical address is ignored.
+ mini2440= [ARM,HW,KNL]
+ Format:[0..2][b][c][t]
+ Default: "0tb"
+ MINI2440 configuration specification:
+ 0 - The attached screen is the 3.5" TFT
+ 1 - The attached screen is the 7" TFT
+ 2 - The VGA Shield is attached (1024x768)
+ Leaving out the screen size parameter will not load
+ the TFT driver, and the framebuffer will be left
+ unconfigured.
+ b - Enable backlight. The TFT backlight pin will be
+ linked to the kernel VESA blanking code and a GPIO
+ LED. This parameter is not necessary when using the
+ VGA shield.
+ c - Enable the s3c camera interface.
+ t - Reserved for enabling touchscreen support. The
+ touchscreen support is not enabled in the mainstream
+ kernel as of 2.6.30, a preliminary port can be found
+ in the "bleeding edge" mini2440 support kernel at
+ http://repo.or.cz/w/linux-2.6/mini2440.git
+
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
parameter allows control of the logging verbosity for
mousedev.yres= [MOUSE] Vertical screen resolution, used for devices
reporting absolute coordinates, such as tablets
- movablecore=nn[KMG] [KNL,X86-32,IA-64,PPC,X86-64] This parameter
+ movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter
is similar to kernelcore except it specifies the
amount of memory used for migratable allocations.
If both kernelcore and movablecore is specified,
mtdparts= [MTD]
See drivers/mtd/cmdlinepart.c.
+ 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
('y', default) or cooked coordinates ('n')
mtrr_chunk_size=nn[KMG] [X86]
- used for mtrr cleanup. It is largest continous chunk
+ used for mtrr cleanup. It is largest continuous chunk
that could hold holes aka. UC entries.
mtrr_gran_size=nn[KMG] [X86]
[NFS] set the TCP port on which the NFSv4 callback
channel should listen.
+ nfs.cache_getent=
+ [NFS] sets the pathname to the program which is used
+ to update the NFS client cache entries.
+
+ nfs.cache_getent_timeout=
+ [NFS] sets the timeout after which an attempt to
+ update a cache entry is deemed to have failed.
+
nfs.idmap_cache_timeout=
[NFS] set the maximum lifetime for idmapper cache
entries.
of returning the full 64-bit number.
The default is to return 64-bit inode numbers.
- nmi_debug= [KNL,AVR32] Specify one or more actions to take
+ nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
when a NMI is triggered.
Format: [state][,regs][,debounce][,die]
- nmi_watchdog= [KNL,BUGS=X86-32,X86-64] Debugging features for SMP kernels
+ nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Format: [panic,][num]
Valid num: 0,1,2
0 - turn nmi_watchdog off
symbolic names: lapic and ioapic
Example: nmi_watchdog=2 or nmi_watchdog=panic,lapic
+ 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.
nodsp [SH] Disable hardware DSP at boot time.
- noefi [X86-32,X86-64] Disable EFI runtime services support.
+ noefi [X86] Disable EFI runtime services support.
noexec [IA-64]
- noexec [X86-32,X86-64]
+ noexec [X86]
On X86-32 available only on PAE configured kernels.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
register save and restore. The kernel will only save
legacy floating-point registers on task switch.
+ noxsave [BUGS=X86] Disables x86 extended register state save
+ and restore using xsave. The kernel will fallback to
+ enabling legacy floating-point and sse state.
+
nohlt [BUGS=ARM,SH] Tells the kernel that the sleep(SH) or
wfi(ARM) instruction doesn't work correctly and not to
use it. This is also useful when using JTAG debugger.
noirqdebug [X86-32] Disables the code which attempts to detect and
disable unhandled interrupt sources.
- no_timer_check [X86-32,X86_64,APIC] Disables the code which tests for
+ no_timer_check [X86,APIC] Disables the code which tests for
broken timer IRQ sources.
noisapnp [ISAPNP] Disables ISA PnP code.
noinitrd [RAM] Tells the kernel not to load any configured
initial RAM disk.
+ nointremap [X86-64, Intel-IOMMU] Do not enable interrupt
+ remapping.
+
nointroute [IA-64]
nojitter [IA64] Disables jitter checking for ITC timers.
oprofile.timer= [HW]
Use timer interrupt instead of performance counters
+ oprofile.cpu_type= Force an oprofile cpu type
+ This might be useful if you have an older oprofile
+ userland or if you want common events.
+ Format: { arch_perfmon }
+ arch_perfmon: [X86] Force use of architectural
+ perfmon on Intel CPUs instead of the
+ CPU specific event set.
+
osst= [HW,SCSI] SCSI Tape Driver
Format: <buffer_size>,<write_threshold>
See also Documentation/scsi/st.txt.
disable the use of PCIE advanced error reporting.
nodomains [PCI] Disable support for multiple PCI
root domains (aka PCI segments, in ACPI-speak).
- nommconf [X86-32,X86_64] Disable use of MMCONFIG for PCI
+ nommconf [X86] Disable use of MMCONFIG for PCI
Configuration
+ check_enable_amd_mmconf [X86] check for and enable
+ properly configured MMIO access to PCI
+ config space on AMD family 10h CPU
nomsi [MSI] If the PCI_MSI kernel config parameter is
enabled, this kernel boot option can be used to
disable the use of MSI interrupts system-wide.
PAGE_SIZE is used as alignment.
PCI-PCI bridge can be specified, if resource
windows need to be expanded.
+ ecrc= Enable/disable PCIe ECRC (transaction layer
+ end-to-end CRC checking).
+ bios: Use BIOS/firmware settings. This is the
+ the default.
+ off: Turn ECRC off
+ on: Turn ECRC on.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
Format: { 0 | 1 }
See arch/parisc/kernel/pdc_chassis.c
+ percpu_alloc= Select which percpu first chunk allocator to use.
+ Currently supported values are "embed" and "page".
+ Archs may support subset or none of the selections.
+ See comments in mm/percpu.c for details on each
+ allocator. This parameter is primarily for debugging
+ and performance comparison.
+
pf. [PARIDE]
See Documentation/blockdev/paride.txt.
autoconfiguration.
Ranges are in pairs (memory base and size).
+ ports= [IP_VS_FTP] IPVS ftp helper module
+ Default is 21.
+ Up to 8 (IP_VS_APP_MAX_PORTS) ports
+ may be specified.
+ Format: <port>,<port>....
+
print-fatal-signals=
[KNL] debug: print fatal signals
print-fatal-signals=1: print segfault info to
stifb= [HW]
Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
+ sunrpc.min_resvport=
+ sunrpc.max_resvport=
+ [NFS,SUNRPC]
+ SunRPC servers often require that client requests
+ originate from a privileged port (i.e. a port in the
+ range 0 < portnr < 1024).
+ An administrator who wishes to reserve some of these
+ ports for other uses may adjust the range that the
+ kernel's sunrpc client considers to be privileged
+ using these two parameters to set the minimum and
+ maximum port values.
+
sunrpc.pool_mode=
[NFS]
Control how the NFS server code allocates CPUs to
pernode one pool for each NUMA node (equivalent
to global on non-NUMA machines)
+ sunrpc.tcp_slot_table_entries=
+ sunrpc.udp_slot_table_entries=
+ [NFS,SUNRPC]
+ Sets the upper limit on the number of simultaneous
+ RPC calls that can be sent from the client to a
+ server. Increasing these values may allow you to
+ improve throughput, but will also increase the
+ amount of memory reserved for use by the client.
+
swiotlb= [IA-64] Number of I/O TLB slabs
switches= [HW,M68k]
tp720= [HW,PS2]
- trace_buf_size=nn[KMG] [ftrace] will set tracing buffer size.
+ trace_buf_size=nn[KMG]
+ [FTRACE] will set tracing buffer size.
+
+ trace_event=[event-list]
+ [FTRACE] Set and start specified trace events in order
+ to facilitate early boot debugging.
+ See also Documentation/trace/events.txt
trix= [HW,OSS] MediaTrix AudioTrix Pro
Format:
reported either.
unknown_nmi_panic
- [X86-32,X86-64]
+ [X86]
Set unknown_nmi_panic=1 early on boot.
usbcore.autosuspend=
medium is write-protected).
Example: quirks=0419:aaf5:rl,0421:0433:rc
- vdso= [X86-32,SH,x86-64]
+ vdso= [X86,SH]
vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)
vdso=0: disable VDSO mapping
- vdso32= [X86-32,X86-64]
+ 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