default: 0
acpi_sleep= [HW,ACPI] Sleep options
- Format: { s3_bios, s3_mode, s3_beep }
+ Format: { s3_bios, s3_mode, s3_beep, old_ordering }
See Documentation/power/video.txt for 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.
+ old_ordering causes the ACPI 1.0 ordering of the _PTS
+ control method, wrt putting devices into low power
+ states, to be enforced (the ACPI 2.0 ordering of _PTS is
+ used by default).
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
Format: { level | edge | high | low }
aic79xx= [HW,SCSI]
See Documentation/scsi/aic79xx.txt.
+ amd_iommu= [HW,X86-84]
+ Pass parameters to the AMD IOMMU driver in the system.
+ Possible values are:
+ isolate - enable device isolation (each device, as far
+ as possible, will get its own protection
+ domain)
+ 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>
when initialising the APIC and IO-APIC components.
apm= [APM] Advanced Power Management
- See header of arch/i386/kernel/apm.c.
+ See header of arch/x86/kernel/apm_32.c.
arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
Format: <io>,<irq>,<nodeID>
possible to determine what the correct size should be.
This option provides an override for these situations.
+ security= [SECURITY] Choose a security module to enable at boot.
+ If this boot parameter is not specified, only the first
+ security module asking for security registration will be
+ loaded. An invalid security module name will be treated
+ as if no module has been chosen.
+
capability.disable=
[SECURITY] Disable capabilities. This would normally
be used only if an alternative security model is to be
cio_ignore= [S390]
See Documentation/s390/CommonIO for details.
- cio_msg= [S390]
- See Documentation/s390/CommonIO for details.
-
clock= [BUGS=X86-32, HW] gettimeofday clocksource override.
[Deprecated]
Forces specified clocksource (if available) to be used
switching to the matching ttyS device later. The
options are the same as for ttyS, above.
+ If the device connected to the port is not a TTY but a braille
+ device, prepend "brl," before the device type, for instance
+ console=brl,ttyS0
+ For now, only VisioBraille is supported.
+
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
1 will print _a lot_ more information - normally
only useful to kernel developers.
+ debug_objects [KNL] Enable object debugging
+
+ debugpat [X86] Enable PAT debugging
+
decnet.addr= [HW,NET]
Format: <area>[,<node>]
See also Documentation/networking/decnet.txt.
See drivers/char/README.epca and
Documentation/digiepca.txt.
+ disable_mtrr_cleanup [X86]
+ enable_mtrr_cleanup [X86]
+ The kernel tries to adjust MTRR layout from continuous
+ to discrete, to make X server driver able to add WB
+ entry later. This parameter enables/disables that.
+
+ mtrr_chunk_size=nn[KMG] [X86]
+ used for mtrr cleanup. It is largest continous chunk
+ that could hold holes aka. UC entries.
+
+ mtrr_gran_size=nn[KMG] [X86]
+ Used for mtrr cleanup. It is granularity of mtrr block.
+ Default is 1.
+ Large value could prevent small alignment from
+ using up MTRRs.
+
+ mtrr_spare_reg_nr=n [X86]
+ Format: <integer>
+ Range: 0,7 : spare reg number
+ Default : 1
+ Used for mtrr cleanup. It is spare mtrr entries number.
+ Set to 2 or more if your graphical card needs more.
+
disable_mtrr_trim [X86, Intel and AMD only]
By default the kernel will trim any uncacheable
memory out of your available memory pool based on
eata= [HW,SCSI]
edd= [EDD]
- Format: {"of[f]" | "sk[ipmbr]"}
- See comment in arch/i386/boot/edd.S
+ Format: {"off" | "on" | "skip[mbr]"}
eisa_irq_edge= [PARISC,HW]
See header of drivers/parisc/eisa.c.
elanfreq= [X86-32]
See comment before function elanfreq_setup() in
- arch/i386/kernel/cpu/cpufreq/elanfreq.c.
+ arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
floppy= [HW]
See Documentation/floppy.txt.
+ force_pal_cache_flush
+ [IA-64] Avoid check_sal_cache_flush which may hang on
+ buggy SAL_CACHE_FLUSH implementations. Using this
+ parameter will force ia64_sal_cache_flush to call
+ ia64_pal_cache_flush instead of SAL_CACHE_FLUSH.
+
gamecon.map[2|3]=
[HW,JOY] Multisystem joystick and NES/SNES/PSX pad
support via parallel port (up to 5 devices per port)
hd= [EIDE] (E)IDE hard drive subsystem geometry
Format: <cyl>,<head>,<sect>
- hd?= [HW] (E)IDE subsystem
- hd?lun= See Documentation/ide/ide.txt.
-
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
Format: <io>[,<membase>[,<icn_id>[,<icn_id2>]]]
ide= [HW] (E)IDE subsystem
- Format: ide=nodma or ide=doubler or ide=reverse
- See Documentation/ide/ide.txt.
-
- ide?= [HW] (E)IDE subsystem
- Format: ide?=noprobe or chipset specific parameters.
+ Format: ide=nodma or ide=doubler
See Documentation/ide/ide.txt.
idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
See Documentation/ide/ide.txt.
idle= [X86]
- Format: idle=poll or idle=mwait
+ Format: idle=poll or idle=mwait, idle=halt, idle=nomwait
Poll forces a polling idle loop that can slightly improves the performance
of waking up a idle CPU, but will use a lot of power and make the system
run hot. Not recommended.
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
ide-pci-generic.all-generic-ide [HW] (E)IDE subsystem
Claim all unknown PCI IDE storage controllers.
inttest= [IA64]
+ iommu= [x86]
+ off
+ force
+ noforce
+ biomerge
+ panic
+ nopanic
+ merge
+ nomerge
+ forcesac
+ soft
+
+
intel_iommu= [DMAR] Intel IOMMU driver (DMAR) option
off
Disable intel iommu driver.
than 32 bit addressing. The default is to look
for translation below 32 bit and if not available
then look in the higher range.
+ strict [Default Off]
+ With this option on every unmap_single operation will
+ result in a hardware IOTLB flush operation as opposed
+ to batching them for performance.
io_delay= [X86-32,X86-64] I/O delay method
0x80
kstack=N [X86-32,X86-64] Print N words from the kernel stack
in oops dumps.
+ kgdboc= [HW] kgdb over consoles.
+ Requires a tty driver that supports console polling.
+ (only serial suported for now)
+ Format: <serial_device>[,baud]
+
l2cr= [PPC]
+ l3cr= [PPC]
+
lapic [X86-32,APIC] Enable the local APIC even if BIOS
disabled it.
mac5380= [HW,SCSI] Format:
<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
- mac53c9x= [HW,SCSI] Format:
- <num_esps>,<disconnect>,<nosync>,<can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
-
machvec= [IA64] Force the use of a particular machine-vector
(machvec) in a generic kernel.
Example: machvec=hpzx1_swiotlb
or
memmap=0x10000$0x18690000
+ memtest= [KNL,X86] Enable memtest
+ Format: <integer>
+ range: 0,4 : pattern number
+ default : 0 <disable>
+
meye.*= [HW] Set MotionEye Camera parameters
See Documentation/video4linux/meye.txt.
mtdparts= [MTD]
See drivers/mtd/cmdlinepart.c.
+ mtdset= [ARM]
+ ARM/S3C2412 JIVE boot control
+
+ See arch/arm/mach-s3c2412/mach-jive.c
+
mtouchusb.raw_coordinates=
[HW] Make the MicroTouch USB driver use raw coordinates
('y', default) or cooked coordinates ('n')
This usage is only documented in each driver source
file if at all.
+ nf_conntrack.acct=
+ [NETFILTER] Enable connection tracking flow accounting
+ 0 to disable accounting
+ 1 to enable accounting
+ Default value depends on CONFIG_NF_CT_ACCT that is
+ going to be removed in 2.6.29.
+
nfsaddrs= [NFS]
See Documentation/filesystems/nfsroot.txt.
noexec [IA-64]
noexec [X86-32,X86-64]
+ On X86-32 available only on PAE configured kernels.
noexec=on: enable non-executable mappings (default)
- noexec=off: disable nn-executable mappings
+ noexec=off: disable non-executable mappings
+
+ noexec32 [X86-64]
+ This affects only 32-bit executables.
+ noexec32=on: enable non-executable mappings (default)
+ read doesn't imply executable mappings
+ noexec32=off: disable non-executable mappings
+ read implies executable mappings
nofxsr [BUGS=X86-32] Disables x86 floating point extended
register save and restore. The kernel will only save
nowb [ARM]
+ nptcg= [IA64] Override max number of concurrent global TLB
+ purges which is reported from either PAL_VM_SUMMARY or
+ SAL PALO.
+
numa_zonelist_order= [KNL, BOOT] Select zonelist order for NUMA.
one of ['zone', 'node', 'default'] can be specified
This can be set from sysctl after boot.
nr_uarts= [SERIAL] maximum number of UARTs to be registered.
+ olpc_ec_timeout= [OLPC] ms delay when issuing EC commands
+ Rather than timing out after 20 ms if an EC
+ command is not properly ACKed, override the length
+ of the timeout. We have interrupts disabled while
+ waiting for the ACK, so if this is set too high
+ interrupts *may* be lost!
+
opl3= [HW,OSS]
Format: <io>
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.
- nosort [X86-32] Don't sort PCI devices according to
- order given by the PCI BIOS. This sorting is
- done to get a device order compatible with
- older kernels.
biosirq [X86-32] Use PCI BIOS calls to get the interrupt
routing table. These calls are known to be buggy
on several machines and they hang the machine
Use with caution as certain devices share
address decoders between ROMs and other
resources.
+ norom [X86-32,X86_64] Do not assign address space to
+ expansion ROMs that do not already have
+ BIOS assigned address ranges.
irqmask=0xMMMM [X86-32] Set a bit mask of IRQs allowed to be
assigned automatically to PCI devices. You can
make the kernel exclude IRQs of your ISA cards
This is normally done in pci_enable_device(),
so this option is a temporary workaround
for broken drivers that don't call it.
+ skip_isa_align [X86] do not align io start addr, so can
+ handle more pci cards
firmware [ARM] Do not re-enumerate the bus but instead
just use the configuration from the
bootloader. This is currently used on
Format: { parport<nr> | timid | 0 }
See also Documentation/parport.txt.
+ pmtmr= [X86] Manual setup of pmtmr I/O Port.
+ Override pmtimer IOPort with a hex value.
+ e.g. pmtmr=0x508
+
pnpacpi= [ACPI]
{ off }
Format: <reboot_mode>[,<reboot_mode2>[,...]]
See arch/*/kernel/reboot.c or arch/*/kernel/process.c
+ relax_domain_level=
+ [KNL, SMP] Set scheduler's default relax_domain_level.
+ See Documentation/cpusets.txt.
+
reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
reservetop= [X86-32]
Note that genuine overcurrent events won't be
reported either.
+ unknown_nmi_panic
+ [X86-32,X86-64]
+ Set unknown_nmi_panic=1 early on boot.
+
usbcore.autosuspend=
[USB] The autosuspend time delay (in seconds) used
for newly-detected USB devices (default 2). This
usbhid.mousepoll=
[USBHID] The interval which mice are to be polled at.
+ add_efi_memmap [EFI; x86-32,X86-64] Include EFI memory map in
+ kernel's map of available physical RAM.
+
vdso= [X86-32,SH,x86-64]
vdso=2: enable compat VDSO (default with COMPAT_VDSO)
vdso=1: enable VDSO (default)