AVR32 AVR32 architecture is enabled.
AX25 Appropriate AX.25 support is enabled.
BLACKFIN Blackfin architecture is enabled.
+ DRM Direct Rendering Management support is enabled.
+ DYNAMIC_DEBUG Build in debug messages and enable them at runtime
EDD BIOS Enhanced Disk Drive Services (EDD) is enabled
EFI EFI Partitioning (GPT) is enabled
EIDE EIDE/ATAPI support is enabled.
- DRM Direct Rendering Management support is enabled.
- DYNAMIC_DEBUG Build in debug messages and enable them at runtime
FB The frame buffer device is enabled.
GCOV GCOV profiling is enabled.
HW Appropriate hardware is enabled.
and is between 256 and 4096 characters. It is defined in the file
./include/asm/setup.h as COMMAND_LINE_SIZE.
+Finally, the [KMG] suffix is commonly described after a number of kernel
+parameter values. These 'K', 'M', and 'G' letters represent the _binary_
+multipliers 'Kilo', 'Mega', and 'Giga', equalling 2^10, 2^20, and 2^30
+bytes respectively. Such letter suffixes can also be entirely omitted.
+
acpi= [HW,ACPI,X86]
Advanced Configuration and Power Interface
unusable. The "log_buf_len" parameter may be useful
if you need to capture more output.
- acpi_display_output= [HW,ACPI]
- acpi_display_output=vendor
- acpi_display_output=video
- See above.
-
acpi_irq_balance [HW,ACPI]
ACPI will balance active IRQs
default in APIC mode
acpi_sleep= [HW,ACPI] Sleep options
Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
- old_ordering, s4_nonvs, sci_force_enable }
+ old_ordering, nonvs, sci_force_enable }
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
bttv.pll= See Documentation/video4linux/bttv/Insmod-options
bttv.tuner= and Documentation/video4linux/bttv/CARDLIST
+ bulk_remove=off [PPC] This parameter disables the use of the pSeries
+ firmware feature for flushing multiple hpte entries
+ at a time.
+
c101= [NET] Moxa C101 synchronous serial card
cachesize= [BUGS=X86-32] Override level 2 CPU cache size detection.
[ARM] imx_timer1,OSTS,netx_timer,mpu_timer2,
pxa_timer,timer3,32k_counter,timer0_1
[AVR32] avr32
- [X86-32] pit,hpet,tsc,vmi-timer;
+ [X86-32] pit,hpet,tsc;
scx200_hrt on Geode; cyclone on IBM x440
[MIPS] MIPS
[PARISC] cr16
Format:
<first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>]
- crashkernel=nn[KMG]@ss[KMG]
- [KNL] Reserve a chunk of physical memory to
- hold a kernel to switch to with kexec on panic.
+ crashkernel=size[KMG][@offset[KMG]]
+ [KNL] Using kexec, Linux can switch to a 'crash kernel'
+ upon panic. This parameter reserves the physical
+ memory region [offset, offset + size] for that kernel
+ image. If '@offset' is omitted, then a suitable offset
+ is selected automatically. Check
+ Documentation/kdump/kdump.txt for further details.
crashkernel=range1:size1[,range2:size2,...][@offset]
[KNL] Same as above, but depends on the memory
in the running system. The syntax of range is
start-[end] where start and end are both
a memory unit (amount[KMG]). See also
- Documentation/kdump/kdump.txt for a example.
+ Documentation/kdump/kdump.txt for an example.
cs89x0_dma= [HW,NET]
Format: <dma>
disable= [IPV6]
See Documentation/networking/ipv6.txt.
+ disable_ddw [PPC/PSERIES]
+ Disable Dynamic DMA Window support. Use this if
+ to workaround buggy firmware.
+
disable_ipv6= [IPV6]
See Documentation/networking/ipv6.txt.
dscc4.setup= [NET]
- dynamic_printk Enables pr_debug()/dev_dbg() calls if
- CONFIG_DYNAMIC_PRINTK_DEBUG has been enabled.
- These can also be switched on/off via
- <debugfs>/dynamic_printk/modules
-
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]
ekgdboc= [X86,KGDB] Allow early kernel console debugging
ekgdboc=kbd
- This is desgined to be used in conjunction with
+ This is designed to be used in conjunction with
the boot argument: earlyprintk=vga
edd= [EDD]
arch/x86/kernel/cpu/cpufreq/elanfreq.c.
elevator= [IOSCHED]
- Format: {"anticipatory" | "cfq" | "deadline" | "noop"}
+ Format: {"cfq" | "deadline" | "noop"}
See Documentation/block/as-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
If specified, z/VM IUCV HVC accepts connections
from listed z/VM user IDs only.
+ keep_bootcon [KNL]
+ Do not unregister boot console at start. This is only
+ useful for debugging when something happens in the window
+ between unregistering the boot console and initializing
+ the real console.
+
i2c_bus= [HW] Override the default board specific I2C bus speed
or register an additional I2C bus that is not
registered from board initialization code.
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
controllers
+ i8042.notimeout [HW] Ignore timeout condition signalled by conroller
i8042.reset [HW] Reset the controller during init and cleanup
i8042.unlock [HW] Unlock (ignore) the keylock
With this option on every unmap_single operation will
result in a hardware IOTLB flush operation as opposed
to batching them for performance.
-
+ sp_off [Default Off]
+ By default, super page will be supported if Intel IOMMU
+ has the capability. With this option, super page will
+ not be supported.
intremap= [X86-64, Intel-IOMMU]
Format: { on (default) | off | nosid }
on enable Interrupt Remapping (default)
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.
+ kvm.mmu_audit= [KVM] This is a R/W parameter which allows audit
+ KVM MMU at runtime.
Default is 0 (off)
+ kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
+ Default is 1 (enabled)
+
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)
6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages
- log_buf_len=n Sets the size of the printk ring buffer, in bytes.
- Format: { n | nk | nM }
- n must be a power of two. The default size
- is set in the kernel config file.
+ log_buf_len=n[KMG] Sets the size of the printk ring buffer,
+ in bytes. n must be a power of two. The default
+ size is set in the kernel config file.
logo.nologo [FB] Disables display of the built-in Linux logo.
This may be used to provide more screen space for
mtdparts= [MTD]
See drivers/mtd/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]
1 to enable accounting
Default value is 0.
- nfsaddrs= [NFS]
+ nfsaddrs= [NFS] Deprecated. Use ip= instead.
See Documentation/filesystems/nfs/nfsroot.txt.
nfsroot= [NFS] nfs root filesystem for disk-less boxes.
See Documentation/filesystems/nfs/nfsroot.txt.
+ nfsrootdebug [NFS] enable nfsroot debugging messages.
+ See Documentation/filesystems/nfs/nfsroot.txt.
+
nfs.callback_tcpport=
[NFS] set the TCP port on which the NFSv4 callback
channel should listen.
of returning the full 64-bit number.
The default is to return 64-bit inode numbers.
+ nfs.nfs4_disable_idmapping=
+ [NFSv4] When set, this option disables the NFSv4
+ idmapper on the client, but only if the mount
+ is using the 'sec=sys' security flavour. This may
+ make migration from legacy NFSv2/v3 systems easier
+ provided that the server has the appropriate support.
+ The default is to always enable NFSv4 idmapping.
+
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] Debugging features for SMP kernels
- Format: [panic,][num]
- Valid num: 0,1,2
+ Format: [panic,][nopanic,][num]
+ Valid num: 0
0 - turn nmi_watchdog off
- 1 - use the IO-APIC timer for the NMI watchdog
- 2 - use the local APIC for the NMI watchdog using
- a performance counter. Note: This will use one
- performance counter and the local APIC's performance
- vector.
When panic is specified, panic when an NMI watchdog
- timeout occurs.
+ timeout occurs (or 'nopanic' to override the opposite
+ default).
This is useful when you use a panic=... timeout and
need the box quickly up again.
- Instead of 1 and 2 it is possible to use the following
- 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
noapic [SMP,APIC] Tells the kernel to not make use of any
IOAPICs that may be present in the system.
+ noautogroup Disable scheduler automatic task group creation.
+
nobats [PPC] Do not use BATs for mapping kernel lowmem
on "Classic" PPC cores.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings
+ nosmep [X86]
+ Disable SMEP (Supervisor Mode Execution Protection)
+ even if it is supported by processor.
+
noexec32 [X86-64]
This affects only 32-bit executables.
noexec32=on: enable non-executable mappings (default)
nojitter [IA64] Disables jitter checking for ITC timers.
+ no-kvmclock [X86,KVM] Disable paravirtualized KVM clock driver
+
+ no-kvmapf [X86,KVM] Disable paravirtualized asynchronous page
+ fault handling.
+
+ no-steal-acc [X86,KVM] Disable paravirtualized steal time accounting.
+ steal time is computed, but won't influence scheduler
+ behaviour
+
nolapic [X86-32,APIC] Do not enable or use the local APIC.
nolapic_timer [X86-32,APIC] Do not use the local APIC timer.
norandmaps Don't use address space randomization. Equivalent to
echo 0 > /proc/sys/kernel/randomize_va_space
- noreplace-paravirt [X86-32,PV_OPS] Don't patch paravirt_ops
+ noreplace-paravirt [X86,IA-64,PV_OPS] Don't patch paravirt_ops
noreplace-smp [X86-32,SMP] Don't replace SMP instructions
with UP alternatives
nosoftlockup [KNL] Disable the soft-lockup detector.
- noswapaccount [KNL] Disable accounting of swap in memory resource
- controller. (See Documentation/cgroups/memory.txt)
-
nosync [HW,M68K] Disables sync negotiation for all devices.
notsc [BUGS=X86-32] Disable Time Stamp Counter
nousb [USB] Disable the USB subsystem
- nowatchdog [KNL] Disable the lockup detector.
+ nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
nowb [ARM]
perfmon on Intel CPUs instead of the
CPU specific event set.
+ oops=panic Always panic on oopses. Default is to just kill the
+ process, but there is a small probability of
+ deadlocking the machine.
+ This will also cause panics on machine check exceptions.
+ Useful together with panic=30 to trigger a reboot.
+
OSS [HW,OSS]
See Documentation/sound/oss/oss-parameters.txt
- panic= [KNL] Kernel behaviour on panic
+ panic= [KNL] Kernel behaviour on panic: delay <timeout>
+ seconds before rebooting
Format: <timeout>
parkbd.port= [HW] Parallel port number the keyboard adapter is
the default.
off: Turn ECRC off
on: Turn ECRC on.
+ realloc reallocate PCI resources if allocations done by BIOS
+ are erroneous.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
Reserves a hole at the top of the kernel virtual
address space.
+ reservelow= [X86]
+ Format: nn[K]
+ Set the amount of memory to reserve for BIOS at
+ the bottom of the address space.
+
reset_devices [KNL] Force drivers to reset the underlying device
during initialization.
in <PAGE_SIZE> units (needed only for swap files).
See Documentation/power/swsusp-and-swap-files.txt
+ hibernate= [HIBERNATION]
+ noresume Don't check if there's a hibernation image
+ present during boot.
+ nocompress Don't compress/decompress hibernation images.
+
retain_initrd [RAM] Keep initrd memory after extraction
rhash_entries= [KNL,NET]
softlockup_panic=
[KNL] Should the soft-lockup detector generate panics.
+ Format: <integer>
sonypi.*= [HW] Sony Programmable I/O Control Device driver
See Documentation/sonypi.txt
improve throughput, but will also increase the
amount of memory reserved for use by the client.
+ swapaccount[=0|1]
+ [KNL] Enable accounting of swap in memory resource
+ controller if no parameter or 1 is given or disable
+ it if 0 is given (See Documentation/cgroups/memory.txt)
+
swiotlb= [IA-64] Number of I/O TLB slabs
switches= [HW,M68k]
<deci-seconds>: poll all this frequency
0: no polling (default)
+ threadirqs [KNL]
+ Force threading of all interrupt handlers except those
+ marked explicitely IRQF_NO_THREAD.
+
topology= [S390]
Format: {off | on}
Specify if the kernel should make use of the cpu
- topology informations if the hardware supports these.
- The scheduler will make use of these informations and
+ topology information if the hardware supports this.
+ The scheduler will make use of this information and
e.g. base its process migration decisions on it.
- Default is off.
+ Default is on.
tp720= [HW,PS2]
to facilitate early boot debugging.
See also Documentation/trace/events.txt
- tsc= Disable clocksource-must-verify flag for TSC.
+ tsc= Disable clocksource stability checks for TSC.
Format: <string>
[x86] reliable: mark tsc clocksource as reliable, this
- disables clocksource verification at runtime.
- Used to enable high-resolution timer mode on older
- hardware, and in virtualized environment.
+ disables clocksource verification at runtime, as well
+ as the stability checks done at bootup. Used to enable
+ high-resolution timer mode on older hardware, and in
+ virtualized environment.
+ [x86] noirqtime: Do not use TSC to do irq accounting.
+ Used to run time disable IRQ_TIME_ACCOUNTING on any
+ platforms where RDTSC is slow and this accounting
+ can add overhead.
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface
reported either.
unknown_nmi_panic
- [X86]
- Set unknown_nmi_panic=1 early on boot.
+ [X86] Cause panic on unknown NMI.
usbcore.autosuspend=
[USB] The autosuspend time delay (in seconds) used
bytes of sense data);
c = FIX_CAPACITY (decrease the reported
device capacity by one sector);
+ d = NO_READ_DISC_INFO (don't use
+ READ_DISC_INFO command);
+ e = NO_READ_CAPACITY_16 (don't use
+ READ_CAPACITY_16 command);
h = CAPACITY_HEURISTICS (decrease the
reported device capacity by one
sector if the number is odd);
unlock ejectable media);
m = MAX_SECTORS_64 (don't transfer more
than 64 sectors = 32 KB at a time);
+ n = INITIAL_READ10 (force a retry of the
+ initial READ(10) command);
o = CAPACITY_OK (accept the capacity
reported by the device);
r = IGNORE_RESIDUE (the device reports