-February 2003 Kernel Parameters v2.5.59
+ Kernel Parameters
~~~~~~~~~~~~~~~~~
The following is a consolidated list of the kernel parameters as implemented
usbcore.blinkenlights=1
-The text in square brackets at the beginning of the description state the
-restrictions on the kernel for the said kernel parameter to be valid. The
-restrictions referred to are that the relevant option is valid if:
+This document may not be entirely up to date and comprehensive. The command
+"modinfo -p ${modulename}" shows a current list of all parameters of a loadable
+module. Loadable modules, after being loaded into the running kernel, also
+reveal their parameters in /sys/module/${modulename}/parameters/. Some of these
+parameters may be changed at runtime by the command
+"echo -n ${value} > /sys/module/${modulename}/parameters/${parm}".
+
+The parameters listed below are only valid if certain kernel build options were
+enabled and if respective hardware is present. The text in square brackets at
+the beginning of each description states the restrictions within which a
+parameter is applicable:
ACPI ACPI support is enabled.
ALSA ALSA sound support is enabled.
APM Advanced Power Management support is enabled.
AX25 Appropriate AX.25 support is enabled.
CD Appropriate CD support is enabled.
- DEVFS devfs support is enabled.
- DRM Direct Rendering Management support is enabled.
+ DEVFS devfs support is enabled.
+ DRM Direct Rendering Management support is enabled.
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
EFI EFI Partitioning (GPT) is enabled
EIDE EIDE/ATAPI support is enabled.
IA-32 IA-32 aka i386 architecture is enabled.
IA-64 IA-64 architecture is enabled.
IOSCHED More than one I/O scheduler is enabled.
- IP_PNP IP DCHP, BOOTP, or RARP is enabled.
+ IP_PNP IP DHCP, BOOTP, or RARP is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
JOY Appropriate joystick support is enabled.
MCA MCA bus support is enabled.
MDA MDA console support is enabled.
MOUSE Appropriate mouse support is enabled.
+ MSI Message Signaled Interrupts (PCI).
MTD MTD support is enabled.
NET Appropriate network support is enabled.
NUMA NUMA support is enabled.
SERIAL Serial support is enabled.
SMP The kernel is an SMP kernel.
SPARC Sparc architecture is enabled.
- SWSUSP Software suspension is enabled.
+ SWSUSP Software suspend is enabled.
TS Appropriate touchscreen support is enabled.
USB USB support is enabled.
USBHID USB Human Interface Device support is enabled.
See header of drivers/scsi/53c7xx.c.
See also Documentation/scsi/ncr53c7xx.txt.
- acpi= [HW,ACPI] Advanced Configuration and Power Interface
- Format: { force | off | ht | strict }
+ acpi= [HW,ACPI] Advanced Configuration and Power Interface
+ Format: { force | off | ht | strict | noirq }
force -- enable ACPI if default was off
off -- disable ACPI if default was on
noirq -- do not use ACPI for IRQ routing
ht -- run only enough ACPI to enable Hyper Threading
- strict -- Be less tolerant of platforms that are not
+ strict -- Be less tolerant of platforms that are not
strictly ACPI specification compliant.
See also Documentation/pm.txt, pci=noacpi
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode }
See Documentation/power/video.txt
-
+
acpi_sci= [HW,ACPI] ACPI System Control Interrupt trigger mode
- Format: { level | edge | high | low }
+ Format: { level | edge | high | low }
- acpi_irq_balance [HW,ACPI] ACPI will balance active IRQs
- default in APIC mode
+ acpi_irq_balance [HW,ACPI]
+ ACPI will balance active IRQs
+ default in APIC mode
- acpi_irq_nobalance [HW,ACPI] ACPI will not move active IRQs (default)
- default in PIC mode
+ acpi_irq_nobalance [HW,ACPI]
+ ACPI will not move active IRQs (default)
+ default in PIC mode
- acpi_irq_pci= [HW,ACPI] If irq_balance, Clear listed IRQs for use by PCI
+ acpi_irq_pci= [HW,ACPI] If irq_balance, clear listed IRQs for
+ use by PCI
Format: <irq>,<irq>...
- acpi_irq_isa= [HW,ACPI] If irq_balance, Mark listed IRQs used by ISA
+ acpi_irq_isa= [HW,ACPI] If irq_balance, mark listed IRQs used by ISA
Format: <irq>,<irq>...
acpi_osi= [HW,ACPI] empty param disables _OSI
acpi_dbg_layer= [HW,ACPI]
Format: <int>
- Each bit of the <int> indicates an acpi debug layer,
+ Each bit of the <int> indicates an ACPI debug layer,
1: enable, 0: disable. It is useful for boot time
debugging. After system has booted up, it can be set
via /proc/acpi/debug_layer.
acpi_dbg_level= [HW,ACPI]
Format: <int>
- Each bit of the <int> indicates an acpi debug level,
+ Each bit of the <int> indicates an ACPI debug level,
1: enable, 0: disable. It is useful for boot time
debugging. After system has booted up, it can be set
via /proc/acpi/debug_level.
acpi_fake_ecdt [HW,ACPI] Workaround failure due to BIOS lacking ECDT
+ acpi_generic_hotkey [HW,ACPI]
+ Allow consolidated generic hotkey driver to
+ override platform specific driver.
+ See also Documentation/acpi-hotkey.txt.
+
+ enable_timer_pin_1 [i386,x86-64]
+ Enable PIN 1 of APIC timer
+ Can be useful to work around chipset bugs
+ (in particular on some ATI chipsets).
+ The kernel tries to set a reasonable default.
+
+ disable_timer_pin_1 [i386,x86-64]
+ Disable PIN 1 of APIC timer
+ Can be useful to work around chipset bugs.
+
ad1816= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
See also Documentation/sound/oss/AD1816.
adlib= [HW,OSS]
Format: <io>
-
+
advansys= [HW,SCSI]
See header of drivers/scsi/advansys.c.
aedsp16= [HW,OSS] Audio Excel DSP 16
Format: <io>,<irq>,<dma>,<mss_io>,<mpu_io>,<mpu_irq>
See also header of sound/oss/aedsp16.c.
-
+
aha152x= [HW,SCSI]
See Documentation/scsi/aha152x.txt.
aic79xx= [HW,SCSI]
See Documentation/scsi/aic79xx.txt.
- AM53C974= [HW,SCSI]
- Format: <host-scsi-id>,<target-scsi-id>,<max-rate>,<max-offset>
- See also header of drivers/scsi/AM53C974.c.
-
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Format: <a>,<b>
connected to one of 16 gameports
Format: <type1>,<type2>,..<type16>
- apc= [HW,SPARC] Power management functions (SPARCstation-4/5 + deriv.)
+ apc= [HW,SPARC]
+ Power management functions (SPARCstation-4/5 + deriv.)
Format: noidle
Disable APC CPU standby support. SPARCstation-Fox does
not play well with APC CPU idle - disable it if you have
APC and your system crashes randomly.
- apic= [APIC,i386] Change the output verbosity whilst booting
+ apic= [APIC,i386] Change the output verbosity whilst booting
Format: { quiet (default) | verbose | debug }
Change the amount of debugging information output
when initialising the APIC and IO-APIC components.
-
+
apm= [APM] Advanced Power Management
See header of arch/i386/kernel/apm.c.
applicom= [HW]
Format: <mem>,<irq>
-
+
arcrimi= [HW,NET] ARCnet - "RIM I" (entirely mem-mapped) cards
Format: <io>,<irq>,<nodeID>
atkbd.reset= [HW] Reset keyboard during initialization
- atkbd.set= [HW] Select keyboard code set
- Format: <int> (2 = AT (default) 3 = PS/2)
+ atkbd.set= [HW] Select keyboard code set
+ Format: <int> (2 = AT (default), 3 = PS/2)
atkbd.scroll= [HW] Enable scroll wheel on MS Office and similar
keyboards
atkbd.softraw= [HW] Choose between synthetic and real raw mode
Format: <bool> (0 = real, 1 = synthetic (default))
-
- atkbd.softrepeat=
- [HW] Use software keyboard repeat
+
+ atkbd.softrepeat= [HW]
+ Use software keyboard repeat
autotest [IA64]
awe= [HW,OSS] AWE32/SB32/AWE64 wave table synth
Format: <io>,<memsize>,<isapnp>
-
+
aztcd= [HW,CD] Aztech CD268 CDROM driver
Format: <io>,0x79 (?)
baycom_epp= [HW,AX25]
Format: <io>,<mode>
-
+
baycom_par= [HW,AX25] BayCom Parallel Port AX.25 Modem
Format: <io>,<mode>
See header of drivers/net/hamradio/baycom_par.c.
- baycom_ser_fdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Full Duplex Mode)
+ baycom_ser_fdx= [HW,AX25]
+ BayCom Serial Port AX.25 Modem (Full Duplex Mode)
Format: <io>,<irq>,<mode>[,<baud>]
See header of drivers/net/hamradio/baycom_ser_fdx.c.
- baycom_ser_hdx= [HW,AX25] BayCom Serial Port AX.25 Modem (Half Duplex Mode)
+ baycom_ser_hdx= [HW,AX25]
+ BayCom Serial Port AX.25 Modem (Half Duplex Mode)
Format: <io>,<irq>,<mode>
See header of drivers/net/hamradio/baycom_ser_hdx.c.
blkmtd_count=
bttv.card= [HW,V4L] bttv (bt848 + bt878 based grabber cards)
- bttv.radio= Most important insmod options are available as kernel args too.
+ bttv.radio= Most important insmod options are available as
+ kernel args too.
bttv.pll= See Documentation/video4linux/bttv/Insmod-options
bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
checkreqprot [SELINUX] Set initial checkreqprot flag value.
Format: { "0" | "1" }
See security/selinux/Kconfig help text.
- 0 -- check protection applied by kernel (includes any implied execute protection).
+ 0 -- check protection applied by kernel (includes
+ any implied execute protection).
1 -- check protection requested by application.
Default value is set via a kernel config option.
- Value can be changed at runtime via /selinux/checkreqprot.
-
- clock= [BUGS=IA-32, HW] gettimeofday timesource override.
+ Value can be changed at runtime via
+ /selinux/checkreqprot.
+
+ clock= [BUGS=IA-32,HW] gettimeofday timesource override.
Forces specified timesource (if avaliable) to be used
- when calculating gettimeofday(). If specicified timesource
- is not avalible, it defaults to PIT.
+ when calculating gettimeofday(). If specicified
+ timesource is not avalible, it defaults to PIT.
Format: { pit | tsc | cyclone | pmtmr }
+ disable_8254_timer
+ enable_8254_timer
+ [IA32/X86_64] Disable/Enable interrupt 0 timer routing
+ over the 8254 in addition to over the IO-APIC. The
+ kernel tries to set a sensible default.
+
hpet= [IA-32,HPET] option to disable HPET and use PIT.
Format: disable
Format: { auto | [<io>,][<irq>] }
com20020= [HW,NET] ARCnet - COM20020 chipset
- Format: <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
+ Format:
+ <io>[,<irq>[,<nodeID>[,<backplane>[,<ckp>[,<timeout>]]]]]
com90io= [HW,NET] ARCnet - COM90xx chipset (IO-mapped buffers)
Format: <io>[,<irq>]
- com90xx= [HW,NET] ARCnet - COM90xx chipset (memory-mapped buffers)
+ com90xx= [HW,NET]
+ ARCnet - COM90xx chipset (memory-mapped buffers)
Format: <io>[,<irq>[,<memstart>]]
condev= [HW,S390] console device
conmode=
-
+
console= [KNL] Output console device and options.
tty<n> Use the virtual console device <n>.
ttyS<n>[,options]
+ ttyUSB0[,options]
Use the specified serial port. The options are of
- the form "bbbbpn", where "bbbb" is the baud rate,
- "p" is parity ("n", "o", or "e"), and "n" is bits.
- Default is "9600n8".
+ the form "bbbbpnf", where "bbbb" is the baud rate,
+ "p" is parity ("n", "o", or "e"), "n" is number of
+ bits, and "f" is flow control ("r" for RTS or
+ omit it). Default is "9600n8".
- See also Documentation/serial-console.txt.
+ See Documentation/serial-console.txt for more
+ information. See
+ Documentation/networking/netconsole.txt for an
+ alternative.
uart,io,<addr>[,options]
uart,mmio,<addr>[,options]
options are the same as for ttyS, above.
cpcihp_generic= [HW,PCI] Generic port I/O CompactPCI driver
- Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
+ Format:
+ <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
cpia_pp= [HW,PPT]
Format: { parport<nr> | auto | none }
+ crashkernel=nn[KMG]@ss[KMG]
+ [KNL] Reserve a chunk of physical memory to
+ hold a kernel to switch to with kexec on panic.
+
cs4232= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpuio>,<mpuirq>
cs89x0_media= [HW,NET]
Format: { rj45 | aui | bnc }
-
+
cyclades= [HW,SERIAL] Cyclades multi-serial port adapter.
-
- dasd= [HW,NET]
+
+ dasd= [HW,NET]
See header of drivers/s390/block/dasd_devmap.c.
db9.dev[2|3]= [HW,JOY] Multisystem joystick support via parallel port
dhash_entries= [KNL]
Set number of hash buckets for dentry cache.
-
+
digi= [HW,SERIAL]
IO parameters + enable/disable command.
dtc3181e= [HW,SCSI]
- earlyprintk= [IA-32, X86-64]
+ earlyprintk= [IA-32,X86-64]
earlyprintk=vga
earlyprintk=serial[,ttySn[,baudrate]]
- Append ,keep to not disable it when the real console
+ Append ",keep" to not disable it when the real console
takes over.
Only vga or serial at a time, not both.
eata= [HW,SCSI]
+ ec_intr= [HW,ACPI] ACPI Embedded Controller interrupt mode
+ Format: <int>
+ 0: polling mode
+ non-0: interrupt mode (default)
+
eda= [HW,PS2]
edb= [HW,PS2]
Format: {"of[f]" | "sk[ipmbr]"}
See comment in arch/i386/boot/edd.S
- eicon= [HW,ISDN]
+ eicon= [HW,ISDN]
Format: <id>,<membase>,<irq>
eisa_irq_edge= [PARISC,HW]
arch/i386/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
- Format: {"as"|"cfq"|"deadline"|"noop"}
- See Documentation/block/as-iosched.txt
- and Documentation/block/deadline-iosched.txt for details.
+ Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
+ See Documentation/block/as-iosched.txt and
+ Documentation/block/deadline-iosched.txt for details.
+
+ elfcorehdr= [IA-32, X86_64]
+ Specifies physical address of start of kernel core
+ image elf header. Generally kexec loader will
+ pass this option to capture kernel.
+ See Documentation/kdump/kdump.txt for details.
enforcing [SELINUX] Set initial enforcing status.
Format: {"0" | "1"}
es1371= [HW,OSS]
Format: <spdif>,[<nomix>,[<amplifier>]]
See also header of sound/oss/es1371.c.
-
+
ether= [HW,NET] Ethernet cards parameters
This option is obsoleted by the "netdev=" option, which
has equivalent usage. See its documentation for details.
gus= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma16>
-
+
gvp11= [HW,SCSI]
hashdist= [KNL,NUMA] Large hashes allocated during boot
are distributed across NUMA nodes. Defaults on
for IA-64, off otherwise.
+ Format: 0 | 1 (for off | on)
hcl= [IA-64] SGI's Hardware Graph compatibility layer
keyboard and can not control its state
(Don't attempt to blink the leds)
i8042.noaux [HW] Don't check for auxiliary (== mouse) port
+ i8042.nokbd [HW] Don't check/create keyboard port
i8042.nomux [HW] Don't check presence of an active multiplexing
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
i810= [HW,DRM]
+ i8k.ignore_dmi [HW] Continue probing hardware even if DMI data
+ indicates that the driver is running on unsupported
+ hardware.
i8k.force [HW] Activate i8k driver even if SMM BIOS signature
does not match list of supported models.
i8k.power_status
ide?= [HW] (E)IDE subsystem
Format: ide?=noprobe or chipset specific parameters.
See Documentation/ide.txt.
-
+
idebus= [HW] (E)IDE subsystem - VLB/PCI bus speed
See Documentation/ide.txt.
idle= [HW]
Format: idle=poll or idle=halt
-
+
ihash_entries= [KNL]
Set number of hash buckets for inode cache.
inport.irq= [HW] Inport (ATI XL and Microsoft) busmouse driver
Format: <irq>
+ combined_mode= [HW] control which driver uses IDE ports in combined
+ mode: legacy IDE driver, libata, or both
+ (in the libata case, libata.atapi_enabled=1 may be
+ useful as well). Note that using the ide or libata
+ options may affect your device naming (e.g. by
+ changing hdc to sdb).
+ Format: combined (default), ide, or libata
+
inttest= [IA64]
io7= [HW] IO7 for Marvel based alpha systems
ips= [HW,SCSI] Adaptec / IBM ServeRAID controller
See header of drivers/scsi/ips.c.
+ irqfixup [HW]
+ When an interrupt is not handled search all handlers
+ for it. Intended to get systems with badly broken
+ firmware running.
+
+ irqpoll [HW]
+ When an interrupt is not handled search all handlers
+ for it. Also check all handlers each timer
+ interrupt. Intended to get systems with badly broken
+ firmware running.
+
isapnp= [ISAPNP]
- Format: <RDP>, <reset>, <pci_scan>, <verbosity>
+ Format: <RDP>,<reset>,<pci_scan>,<verbosity>
isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
Format: <cpu number>,...,<cpu number>
"number of CPUs in system - 1".
This option is the preferred way to isolate CPUs. The
- alternative - manually setting the CPU mask of all tasks
- in the system can cause problems and suboptimal load
- balancer performance.
+ alternative -- manually setting the CPU mask of all
+ tasks in the system -- can cause problems and
+ suboptimal load balancer performance.
isp16= [HW,CD]
Format: <io>,<irq>,<dma>,<setup>
- iucv= [HW,NET]
+ iucv= [HW,NET]
js= [HW,JOY] Analog joystick
See Documentation/input/joystick.txt.
keepinitrd [HW,ARM]
- kstack=N [IA-32, X86-64] Print N words from the kernel stack
+ kstack=N [IA-32,X86-64] Print N words from the kernel stack
in oops dumps.
l2cr= [PPC]
- lapic [IA-32,APIC] Enable the local APIC even if BIOS disabled it.
+ lapic [IA-32,APIC] Enable the local APIC even if BIOS
+ disabled it.
lasi= [HW,SCSI] PARISC LASI driver for the 53c700 chip
Format: addr:<io>,irq:<irq>
- llsc*= [IA64]
- See function print_params() in arch/ia64/sn/kernel/llsc4.c.
+ llsc*= [IA64] See function print_params() in
+ arch/ia64/sn/kernel/llsc4.c.
load_ramdisk= [RAM] List of ramdisks to load from floppy
See Documentation/ramdisk.txt.
- lockd.udpport= [NFS]
+ lockd.nlm_grace_period=P [NFS] Assign grace period.
+ Format: <integer>
+
+ lockd.nlm_tcpport=N [NFS] Assign TCP port.
+ Format: <integer>
+
+ lockd.nlm_timeout=T [NFS] Assign timeout value.
+ Format: <integer>
- lockd.tcpport= [NFS]
+ lockd.nlm_udpport=M [NFS] Assign UDP port.
+ Format: <integer>
logibm.irq= [HW,MOUSE] Logitech Bus Mouse Driver
Format: <irq>
7 (KERN_DEBUG) debug-level messages
log_buf_len=n Sets the size of the printk ring buffer, in bytes.
- Format is n, nk, nM. n must be a power of two. The
- default is set in kernel config.
+ Format: { n | nk | nM }
+ n must be a power of two. The default size
+ is set in the kernel config file.
lp=0 [LP] Specify parallel ports to use, e.g,
lp=port[,port...] lp=none,parport0 (lp0 not configured, lp1 uses
ltpc= [NET]
Format: <io>,<irq>,<dma>
- mac5380= [HW,SCSI]
- Format: <can_queue>,<cmd_per_lun>,<sg_tablesize>,<hostid>,<use_tags>
+ 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>
+ 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
+ machvec= [IA64] Force the use of a particular machine-vector
+ (machvec) in a generic kernel.
+ Example: machvec=hpzx1_swiotlb
- mad16= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
+ mad16= [HW,OSS] Format:
+ <io>,<irq>,<dma>,<dma16>,<mpu_io>,<mpu_irq>,<joystick>
maui= [HW,OSS]
Format: <io>,<irq>
-
- max_loop= [LOOP] Maximum number of loopback devices that can
+
+ max_loop= [LOOP] Maximum number of loopback devices that can
be mounted
Format: <1-256>
maxcpus= [SMP] Maximum number of processors that an SMP kernel
should make use of
- max_luns= [SCSI] Maximum number of LUNs to probe
+ max_addr=[KMG] [KNL,BOOT,ia64] All physical memory greater than or
+ equal to this physical address is ignored.
+
+ max_luns= [SCSI] Maximum number of LUNs to probe.
Should be between 1 and 2^32-1.
max_report_luns=
- [SCSI] Maximum number of LUNs received
+ [SCSI] Maximum number of LUNs received.
Should be between 1 and 16384.
mca-pentium [BUGS=IA-32]
md= [HW] RAID subsystems devices and level
See Documentation/md.txt.
-
+
mdacon= [MDA]
Format: <first>,<last>
Specifies range of consoles to be captured by the MDA.
-
+
mem=nn[KMG] [KNL,BOOT] Force usage of a specific amount of memory
Amount of memory to be used when the kernel is not able
to see the whole system memory or for test.
mem=nopentium [BUGS=IA-32] Disable usage of 4MB pages for kernel
memory.
- memmap=exactmap [KNL,IA-32] Enable setting of an exact
+ memmap=exactmap [KNL,IA-32,X86_64] 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
mga= [HW,DRM]
+ migration_cost=
+ [KNL,SMP] debug: override scheduler migration costs
+ Format: <level-1-usecs>,<level-2-usecs>,...
+ This debugging option can be used to override the
+ default scheduler migration cost matrix. The numbers
+ are indexed by 'CPU domain distance'.
+ E.g. migration_cost=1000,2000,3000 on an SMT NUMA
+ box will set up an intra-core migration cost of
+ 1 msec, an inter-core migration cost of 2 msecs,
+ and an inter-node migration cost of 3 msecs.
+
+ WARNING: using the wrong values here can break
+ scheduler performance, so it's only for scheduler
+ development purposes, not production environments.
+
+ migration_debug=
+ [KNL,SMP] migration cost auto-detect verbosity
+ Format=<0|1|2>
+ If a system's migration matrix reported at bootup
+ seems erroneous then this option can be used to
+ increase verbosity of the detection process.
+ We default to 0 (no extra messages), 1 will print
+ some more information, and 2 will be really
+ verbose (probably only useful if you also have a
+ serial console attached to the system).
+
+ migration_factor=
+ [KNL,SMP] multiply/divide migration costs by a factor
+ Format=<percent>
+ This debug option can be used to proportionally
+ increase or decrease the auto-detected migration
+ costs for all entries of the migration matrix.
+ E.g. migration_factor=150 will increase migration
+ costs by 50%. (and thus the scheduler will be less
+ eager migrating cache-hot tasks)
+ migration_factor=80 will decrease migration costs
+ by 20%. (thus the scheduler will be more eager to
+ migrate tasks)
+
+ WARNING: using the wrong values here can break
+ scheduler performance, so it's only for scheduler
+ development purposes, not production environments.
+
mousedev.tap_time=
[MOUSE] Maximum time between finger touching and
leaving touchpad surface for touch to be considered
MTD_Partition= [MTD]
Format: <name>,<region-number>,<size>,<offset>
- MTD_Region= [MTD]
-
Format: <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
+ MTD_Region= [MTD] Format:
+ <name>,<region-number>[,<base>,<size>,<buswidth>,<altbuswidth>]
mtdparts= [MTD]
See drivers/mtd/cmdline.c.
mtouchusb.raw_coordinates=
- [HW] Make the MicroTouch USB driver use raw coordinates ('y', default)
- or cooked coordinates ('n')
+ [HW] Make the MicroTouch USB driver use raw coordinates
+ ('y', default) or cooked coordinates ('n')
n2= [NET] SDL Inc. RISCom/N2 synchronous serial card
Format: <irq>,<io>,<mem_start>,<mem_end>,<name>
Note that mem_start is often overloaded to mean
something different and driver-specific.
-
+ This usage is only documented in each driver source
+ file if at all.
+
nfsaddrs= [NFS]
See Documentation/nfsroot.txt.
nfsroot= [NFS] nfs root filesystem for disk-less boxes.
See Documentation/nfsroot.txt.
+ nfs.callback_tcpport=
+ [NFS] set the TCP port on which the NFSv4 callback
+ channel should listen.
+
+ nfs.idmap_cache_timeout=
+ [NFS] set the maximum lifetime for idmapper cache
+ entries.
+
nmi_watchdog= [KNL,BUGS=IA-32] Debugging features for SMP kernels
no387 [BUGS=IA-32] Tells the kernel to use the 387 maths
emulation library even if a 387 maths coprocessor
is present.
- noalign [KNL,ARM]
-
+ noalign [KNL,ARM]
+
noapic [SMP,APIC] Tells the kernel to not make use of any
IOAPICs that may be present in the system.
on "Classic" PPC cores.
nocache [ARM]
-
+
nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
noexec [IA-64]
- noexec [IA-32, X86-64]
+ noexec [IA-32,X86-64]
noexec=on: enable non-executable mappings (default)
noexec=off: disable nn-executable mappings
- nofxsr [BUGS=IA-32]
+ nofxsr [BUGS=IA-32] Disables x86 floating point extended
+ register save and restore. The kernel will only save
+ legacy floating-point registers on task switch.
nohlt [BUGS=ARM]
-
+
no-hlt [BUGS=IA-32] Tells the kernel that the hlt
instruction doesn't work correctly and not to
use it.
noltlbs [PPC] Do not use large page/tlb entries for kernel
lowmem mapping on PPC40x.
+ nomca [IA-64] Disable machine check abort handling
+
nomce [IA-32] Machine Check Exception
noresidual [PPC] Don't use residual data on PReP machines.
- noresume [SWSUSP] Disables resume and restore original swap space.
-
+ noresume [SWSUSP] Disables resume and restores original swap
+ space.
+
no-scroll [VGA] Disables scrollback.
This is required for the Braillex ib80-piezo Braille
reader made by F.H. Papenmeier (Germany).
nosbagart [IA-64]
+ nosep [BUGS=IA-32] Disables x86 SYSENTER/SYSEXIT support.
+
nosmp [SMP] Tells an SMP kernel to act as a UP kernel.
nosync [HW,M68K] Disables sync negotiation for all devices.
nousb [USB] Disable the USB subsystem
nowb [ARM]
-
+
+ nr_uarts= [SERIAL] maximum number of UARTs to be registered.
+
opl3= [HW,OSS]
Format: <io>
opl3sa= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<mpu_io>,<mpu_irq>
- opl3sa2= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
-
+ opl3sa2= [HW,OSS] Format:
+ <io>,<irq>,<dma>,<dma2>,<mss_io>,<mpu_io>,<ymode>,<loopback>[,<isapnp>,<multiple]
+
oprofile.timer= [HW]
Use timer interrupt instead of performance counters
Format: <parport#>
parkbd.mode= [HW] Parallel port keyboard adapter mode of operation,
0 for XT, 1 for AT (default is AT).
- Format: <mode>
-
- parport=0 [HW,PPT] Specify parallel ports. 0 disables.
- parport=auto Use 'auto' to force the driver to use
- parport=0xBBB[,IRQ[,DMA]] any IRQ/DMA settings detected (the
- default is to ignore detected IRQ/DMA
- settings because of possible
- conflicts). You can specify the base
- address, IRQ, and DMA settings; IRQ and
- DMA should be numbers, or 'auto' (for
- using detected settings on that
- particular port), or 'nofifo' (to avoid
- using a FIFO even if it is detected).
- Parallel ports are assigned in the
- order they are specified on the command
- line, starting with parport0.
-
- parport_init_mode=
- [HW,PPT] Configure VIA parallel port to
- operate in specific mode. This is
- necessary on Pegasos computer where
- firmware has no options for setting up
- parallel port mode and sets it to
- spp. Currently this function knows
- 686a and 8231 chips.
+ Format: <mode>
+
+ parport= [HW,PPT] Specify parallel ports. 0 disables.
+ Format: { 0 | auto | 0xBBB[,IRQ[,DMA]] }
+ Use 'auto' to force the driver to use any
+ IRQ/DMA settings detected (the default is to
+ ignore detected IRQ/DMA settings because of
+ possible conflicts). You can specify the base
+ address, IRQ, and DMA settings; IRQ and DMA
+ should be numbers, or 'auto' (for using detected
+ settings on that particular port), or 'nofifo'
+ (to avoid using a FIFO even if it is detected).
+ Parallel ports are assigned in the order they
+ are specified on the command line, starting
+ with parport0.
+
+ parport_init_mode= [HW,PPT]
+ Configure VIA parallel port to operate in
+ a specific mode. This is necessary on Pegasos
+ computer where firmware has no options for setting
+ up parallel port mode and sets it to spp.
+ Currently this function knows 686a and 8231 chips.
Format: [spp|ps2|epp|ecp|ecpepp]
- pas2= [HW,OSS]
- Format: <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
-
+ pas2= [HW,OSS] Format:
+ <io>,<irq>,<dma>,<dma16>,<sb_io>,<sb_irq>,<sb_dma>,<sb_dma16>
+
pas16= [HW,SCSI]
See header of drivers/scsi/pas16.c.
+ pause_on_oops=
+ Halt all CPUs after the first oops has been printed for
+ the specified number of seconds. This is to be used if
+ your oopses keep scrolling off the screen.
+
pcbit= [HW,ISDN]
pcd. [PARIDE]
See header of drivers/block/paride/pcd.c.
See also Documentation/paride.txt.
- pci=option[,option...] [PCI] various PCI subsystem options:
- off [IA-32] don't probe for the PCI bus
- bios [IA-32] force use of PCI BIOS, don't access
- the hardware directly. Use this if your machine
- has a non-standard PCI host bridge.
- nobios [IA-32] disallow use of PCI BIOS, only direct
- hardware access methods are allowed. Use this
- if you experience crashes upon bootup and you
- suspect they are caused by the BIOS.
- conf1 [IA-32] Force use of PCI Configuration Mechanism 1.
- conf2 [IA-32] Force use of PCI Configuration Mechanism 2.
- nosort [IA-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 [IA-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 when used,
- but on other computers it's the only way to get the
- interrupt routing table. Try this option if the kernel
- is unable to allocate IRQs or discover secondary PCI
- buses on your motherboard.
- rom [IA-32] Assign address space to expansion ROMs.
- Use with caution as certain devices share address
- decoders between ROMs and other resources.
- irqmask=0xMMMM [IA-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 way.
- lastbus=N [IA-32] Scan all buses till bus #N. Can be useful
- if the kernel is unable to find your secondary buses
- and you want to tell it explicitly which ones they are.
- assign-busses [IA-32] Always assign all PCI bus
- numbers ourselves, overriding
- whatever the firmware may have
- done.
- usepirqmask [IA-32] Honor the possible IRQ mask
- stored in the BIOS $PIR table. This is
- needed on some systems with broken
- BIOSes, notably some HP Pavilion N5400
- and Omnibook XE3 notebooks. This will
- have no effect if ACPI IRQ routing is
- enabled.
- noacpi [IA-32] Do not use ACPI for IRQ routing
- or for PCI scanning.
- routeirq Do IRQ routing for all PCI devices.
- This is normally done in pci_enable_device(),
- so this option is a temporary workaround
- for broken drivers that don't call it.
-
- firmware [ARM] Do not re-enumerate the bus but
- instead just use the configuration
- from the bootloader. This is currently
- used on IXP2000 systems where the
- bus has to be configured a certain way
- for adjunct CPUs.
+ pci=option[,option...] [PCI] various PCI subsystem options:
+ off [IA-32] don't probe for the PCI bus
+ bios [IA-32] force use of PCI BIOS, don't access
+ the hardware directly. Use this if your machine
+ has a non-standard PCI host bridge.
+ nobios [IA-32] disallow use of PCI BIOS, only direct
+ hardware access methods are allowed. Use this
+ if you experience crashes upon bootup and you
+ suspect they are caused by the BIOS.
+ conf1 [IA-32] Force use of PCI Configuration
+ Mechanism 1.
+ conf2 [IA-32] Force use of PCI Configuration
+ Mechanism 2.
+ nommconf [IA-32,X86_64] Disable use of MMCONFIG for PCI
+ Configuration
+ 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 [IA-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 [IA-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
+ when used, but on other computers it's the only
+ way to get the interrupt routing table. Try
+ this option if the kernel is unable to allocate
+ IRQs or discover secondary PCI buses on your
+ motherboard.
+ rom [IA-32] Assign address space to expansion ROMs.
+ Use with caution as certain devices share
+ address decoders between ROMs and other
+ resources.
+ irqmask=0xMMMM [IA-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 way.
+ pirqaddr=0xAAAAA [IA-32] Specify the physical address
+ of the PIRQ table (normally generated
+ by the BIOS) if it is outside the
+ F0000h-100000h range.
+ lastbus=N [IA-32] Scan all buses thru bus #N. Can be
+ useful if the kernel is unable to find your
+ secondary buses and you want to tell it
+ explicitly which ones they are.
+ assign-busses [IA-32] Always assign all PCI bus
+ numbers ourselves, overriding
+ whatever the firmware may have done.
+ usepirqmask [IA-32] Honor the possible IRQ mask stored
+ in the BIOS $PIR table. This is needed on
+ some systems with broken BIOSes, notably
+ some HP Pavilion N5400 and Omnibook XE3
+ notebooks. This will have no effect if ACPI
+ IRQ routing is enabled.
+ noacpi [IA-32] Do not use ACPI for IRQ routing
+ or for PCI scanning.
+ routeirq Do IRQ routing for all PCI devices.
+ This is normally done in pci_enable_device(),
+ so this option is a temporary workaround
+ for broken drivers that don't call it.
+ firmware [ARM] Do not re-enumerate the bus but instead
+ just use the configuration from the
+ bootloader. This is currently used on
+ IXP2000 systems where the bus has to be
+ configured a certain way for adjunct CPUs.
pcmv= [HW,PCMCIA] BadgePAD 4
[ISAPNP] Exclude DMAs for the autoconfiguration
pnp_reserve_io= [ISAPNP] Exclude I/O ports for the autoconfiguration
- Ranges are in pairs (I/O port base and size).
+ Ranges are in pairs (I/O port base and size).
pnp_reserve_mem=
- [ISAPNP] Exclude memory regions for the autoconfiguration
+ [ISAPNP] Exclude memory regions for the
+ autoconfiguration.
Ranges are in pairs (memory base and size).
profile= [KNL] Enable kernel profiling via /proc/profile
- { schedule | <number> }
- (param: schedule - profile schedule points}
- (param: profile step/bucket size as a power of 2 for
- statistical time based profiling)
+ Format: [schedule,]<number>
+ Param: "schedule" - profile schedule points.
+ Param: <number> - step/bucket size as a power of 2 for
+ statistical time based profiling.
- processor.max_cstate= [HW, ACPI]
+ processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
max_cstate=9 overrides any DMI blacklist limit.
+ processor.nocst [HW,ACPI]
+ Ignore the _CST method to determine C-states,
+ instead using the legacy FADT method
+
prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk
before loading.
See Documentation/ramdisk.txt.
- psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
- probe for (bare|imps|exps).
+ psmouse.proto= [HW,MOUSE] Highest PS2 mouse protocol extension to
+ probe for; one of (bare|imps|exps|lifebook|any).
psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
per second.
- psmouse.resetafter=
- [HW,MOUSE] Try to reset the device after so many bad packets
+ psmouse.resetafter= [HW,MOUSE]
+ Try to reset the device after so many bad packets
(0 = never).
psmouse.resolution=
[HW,MOUSE] Set desired mouse resolution, in dpi.
psmouse.smartscroll=
- [HW,MOUSE] Controls Logitech smartscroll autorepeat,
+ [HW,MOUSE] Controls Logitech smartscroll autorepeat.
0 = disabled, 1 = enabled (default).
pss= [HW,OSS] Personal Sound System (ECHO ESC614)
- Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
+ Format:
+ <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
pt. [PARIDE]
See Documentation/paride.txt.
quiet= [KNL] Disable log messages
-
+
r128= [HW,DRM]
raid= [HW,RAID]
ramdisk= [RAM] Sizes of RAM disks in kilobytes [deprecated]
See Documentation/ramdisk.txt.
- ramdisk_blocksize=
- [RAM]
+ ramdisk_blocksize= [RAM]
See Documentation/ramdisk.txt.
-
+
ramdisk_size= [RAM] Sizes of RAM disks in kilobytes
New name for the ramdisk parameter.
See Documentation/ramdisk.txt.
+ rcu.blimit= [KNL,BOOT] Set maximum number of finished
+ RCU callbacks to process in one batch.
+
+ rcu.qhimark= [KNL,BOOT] Set threshold of queued
+ RCU callbacks over which batch limiting is disabled.
+
+ rcu.qlowmark= [KNL,BOOT] Set threshold of queued
+ RCU callbacks below which batch limiting is re-enabled.
+
+ rcu.rsinterval= [KNL,BOOT,SMP] Set the number of additional
+ RCU callbacks to queued before forcing reschedule
+ on all cpus.
+
+ rdinit= [KNL]
+ Format: <full_path>
+ Run specified binary instead of /init from the ramdisk,
+ used for early userspace startup. See initrd.
+
reboot= [BUGS=IA-32,BUGS=ARM,BUGS=IA-64] Rebooting mode
Format: <reboot_mode>[,<reboot_mode2>[,...]]
See arch/*/kernel/reboot.c.
reserve= [KNL,BUGS] Force the kernel to ignore some iomem area
- resume= [SWSUSP] Specify the partition device for software suspension
+ resume= [SWSUSP]
+ Specify the partition device for software suspend
rhash_entries= [KNL,NET]
Set number of hash buckets for route cache
Format: <io>,<irq>,<dma>,<dma2>
sbni= [NET] Granch SBNI12 leased line adapter
-
+
sbpcd= [HW,CD] Soundblaster CD adapter
Format: <io>,<type>
See a comment before function sbpcd_setup() in
serialnumber [BUGS=IA-32]
- sg_def_reserved_size=
- [SCSI]
-
+ sg_def_reserved_size= [SCSI]
+
sgalaxy= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>,<sgbase>
shapers= [NET]
Maximal number of shapers.
-
+
sim710= [SCSI,HW]
See header of drivers/scsi/sim710.c.
simeth= [IA-64]
simscsi=
-
+
sjcd= [HW,CD]
Format: <io>,<irq>,<dma>
See header of drivers/cdrom/sjcd.c.
snd-wavefront= [HW,ALSA]
snd-ymfpci= [HW,ALSA]
-
+
sonicvibes= [HW,OSS]
Format: <reverb>
-
+
sonycd535= [HW,CD]
Format: <io>[,<irq>]
sscape= [HW,OSS]
Format: <io>,<irq>,<dma>,<mpu_io>,<mpu_irq>
-
+
st= [HW,SCSI] SCSI tape parameters (buffers, etc.)
See Documentation/scsi/st.txt.
stifb= [HW]
Format: bpp:<bpp1>[:<bpp2>[:<bpp3>...]]
- stram_swap= [HW,M68k]
-
swiotlb= [IA-64] Number of I/O TLB slabs
-
+
switches= [HW,M68k]
sym53c416= [HW,SCSI]
tp720= [HW,PS2]
trix= [HW,OSS] MediaTrix AudioTrix Pro
- Format: <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
-
+ Format:
+ <io>,<irq>,<dma>,<dma2>,<sb_io>,<sb_irq>,<sb_dma>,<mpu_io>,<mpu_irq>
+
tsdev.xres= [TS] Horizontal screen resolution.
tsdev.yres= [TS] Vertical screen resolution.
- turbografx.map[2|3]=
- [HW,JOY] TurboGraFX parallel port interface
- Format: <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
+ turbografx.map[2|3]= [HW,JOY]
+ TurboGraFX parallel port interface
+ Format:
+ <port#>,<js1>,<js2>,<js3>,<js4>,<js5>,<js6>,<js7>
See also Documentation/input/joystick-parport.txt
u14-34f= [HW,SCSI] UltraStor 14F/34F SCSI host adapter
uart6850= [HW,OSS]
Format: <io>,<irq>
- usb-handoff [HW] Enable early USB BIOS -> OS handoff
-
usbhid.mousepoll=
[USBHID] The interval which mice are to be polled at.
-
+
video= [FB] Frame buffer configuration
See Documentation/fb/modedb.txt.
vga= [BOOT,IA-32] Select a particular video mode
- See Documentation/i386/boot.txt and Documentation/svga.txt.
+ See Documentation/i386/boot.txt and
+ Documentation/svga.txt.
Use vga=ask for menu.
This is actually a boot loader parameter; the value is
passed to the kernel using a special protocol.
- vmalloc=nn[KMG] [KNL,BOOT] forces the vmalloc area to have an exact
+ vmalloc=nn[KMG] [KNL,BOOT] Forces the vmalloc area to have an exact
size of <nn>. This can be used to increase the
minimum size (128MB on x86). It can also be used to
decrease the size and leave more room for directly
vmhalt= [KNL,S390]
- vmpoff= [KNL,S390]
-
+ vmpoff= [KNL,S390]
+
waveartist= [HW,OSS]
Format: <io>,<irq>,<dma>,<dma2>
-
+
wd33c93= [HW,SCSI]
See header of drivers/scsi/wd33c93.c.
xd_geo= See header of drivers/block/xd.c.
xirc2ps_cs= [NET,PCMCIA]
- Format: <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
-
-
+ Format:
+ <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
-Changelog:
+ norandmaps Don't use address space randomization
+ Equivalent to echo 0 > /proc/sys/kernel/randomize_va_space
- The last known update (for 2.4.0) - the changelog was not kept before.
- 2000-06-?? Mr. Unknown
- Update for 2.5.49, description for most of the options introduced,
- references to other documentation (C files, READMEs, ..), added S390,
- PPC, SPARC, MTD, ALSA and OSS category. Minor corrections and
- reformatting.
- 2002-11-24 Petr Baudis <pasky@ucw.cz>
- Randy Dunlap <randy.dunlap@verizon.net>
+______________________________________________________________________
TODO:
git://git.onelab.eu / linux-2.6.git / blobdiff