CPU-intensive style benchmark, and it can vary highly in
a microbenchmark depending on workload and compiler.
- 1: only for 32-bit processes
- 2: only for 64-bit processes
+ 32: only for 32-bit processes
+ 64: only for 64-bit processes
on: enable for both 32- and 64-bit processes
off: disable for both 32- and 64-bit processes
- amd_iommu= [HW,X86-84]
+ amd_iommu= [HW,X86-64]
Pass parameters to the AMD IOMMU driver in the system.
Possible values are:
fullflush - enable flushing of IO/TLB entries when
is a lot of faster
off - do not initialize any AMD IOMMU found in
the system
+ force_isolation - Force device isolation for all
+ devices. The IOMMU driver is not
+ allowed anymore to lift isolation
+ requirements as needed. This option
+ does not override iommu=pt
amijoy.map= [HW,JOY] Amiga joystick support
Map of devices attached to JOY0DAT and JOY1DAT
Also note the kernel might malfunction if you disable
some critical bits.
+ cma=nn[MG] [ARM,KNL]
+ Sets the size of kernel global memory area for contiguous
+ memory allocations. For more information, see
+ include/linux/dma-contiguous.h
+
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
a hypervisor.
Default: yes
+ coherent_pool=nn[KMG] [ARM,KNL]
+ Sets the size of memory pool for coherent, atomic dma
+ allocations, by default set to 256K.
+
code_bytes [X86] How many bytes of object code to print
in an oops report.
Range: 0 - 8192
no_debug_objects
[KNL] Disable object debugging
+ debug_guardpage_minorder=
+ [KNL] When CONFIG_DEBUG_PAGEALLOC is set, this
+ parameter allows control of the order of pages that will
+ be intentionally kept free (and hence protected) by the
+ buddy allocator. Bigger value increase the probability
+ of catching random memory corruption, but reduce the
+ amount of memory for normal system use. The maximum
+ possible value is MAX_ORDER/2. Setting this parameter
+ to 1 or 2 should be enough to identify most random
+ memory corruption problems caused by bugs in kernel or
+ driver code when a CPU writes to (or reads from) a
+ random memory location. Note that there exists a class
+ of memory corruptions problems caused by buggy H/W or
+ F/W or by drivers badly programing DMA (basically when
+ memory is written at bus level and the CPU MMU is
+ bypassed) which are not detectable by
+ CONFIG_DEBUG_PAGEALLOC, hence this option will not help
+ tracking down these problems.
+
debugpat [X86] Enable PAT debugging
decnet.addr= [HW,NET]
The filter can be disabled or changed to another
driver later using sysfs.
+ drm_kms_helper.edid_firmware=[<connector>:]<file>
+ Broken monitors, graphic adapters and KVMs may
+ send no or incorrect EDID data sets. This parameter
+ allows to specify an EDID data set in the
+ /lib/firmware directory that is used instead.
+ Generic built-in EDID data sets are used, if one of
+ edid/1024x768.bin, edid/1280x1024.bin,
+ edid/1680x1050.bin, or edid/1920x1080.bin is given
+ and no file with the same name exists. Details and
+ instructions how to build your own EDID data are
+ available in Documentation/EDID/HOWTO.txt. An EDID
+ data set will only be used for a particular connector,
+ if its name and a colon are prepended to the EDID
+ name.
+
dscc4.setup= [NET]
earlycon= [KNL] Output early console device and options.
See Documentation/block/cfq-iosched.txt and
Documentation/block/deadline-iosched.txt for details.
- elfcorehdr= [IA-64,PPC,SH,X86]
+ elfcorehdr=[size[KMG]@]offset[KMG] [IA64,PPC,SH,X86,S390]
Specifies physical address of start of kernel core
- image elf header. Generally kexec loader will
- pass this option to capture kernel.
+ image elf header and optionally the size. Generally
+ kexec loader will pass this option to capture kernel.
See Documentation/kdump/kdump.txt for details.
enable_mtrr_cleanup [X86]
controller
i8042.nopnp [HW] Don't use ACPIPnP / PnPBIOS to discover KBD/AUX
controllers
- i8042.notimeout [HW] Ignore timeout condition signalled by conroller
+ i8042.notimeout [HW] Ignore timeout condition signalled by controller
i8042.reset [HW] Reset the controller during init and cleanup
i8042.unlock [HW] Unlock (ignore) the keylock
ignore_loglevel [KNL]
Ignore loglevel setting - this will print /all/
kernel messages to the console. Useful for debugging.
+ We also add it as printk module parameter, so users
+ could change it dynamically, usually by
+ /sys/module/printk/parameters/ignore_loglevel.
ihash_entries= [KNL]
Set number of hash buckets for inode cache.
By default, super page will be supported if Intel IOMMU
has the capability. With this option, super page will
not be supported.
+
+ 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.
+
intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)
off disable Interrupt Remapping
no_x2apic_optout
BIOS x2APIC opt-out request will be ignored
- inttest= [IA-64]
-
iomem= Disable strict checking of access to MMIO memory
strict regions from userspace.
relaxed
nomerge
forcesac
soft
- pt [x86, IA-64]
+ pt [x86, IA-64]
+ group_mf [x86, IA-64]
+
io7= [HW] IO7 for Marvel based alpha systems
See comment before marvel_specify_io7 in
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.mmu_audit= [KVM] This is a R/W parameter which allows audit
KVM MMU at runtime.
Default is 0 (off)
[KVM,Intel] Disable FlexPriority feature (TPR shadow).
Default is 1 (enabled)
+ kvm-intel.nested=
+ [KVM,Intel] Enable VMX nesting (nVMX).
+ Default is 0 (disabled)
+
kvm-intel.unrestricted_guest=
[KVM,Intel] Disable unrestricted guest feature
(virtualized real and unpaged mode) on capable
of returning the full 64-bit number.
The default is to return 64-bit inode numbers.
+ nfs.max_session_slots=
+ [NFSv4.1] Sets the maximum number of session slots
+ the client will attempt to negotiate with the server.
+ This limits the number of simultaneous RPC requests
+ that the client can send to the NFSv4.1 server.
+ Note that there is little point in setting this
+ value higher than the max_tcp_slot_table_limit.
+
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.
+ [NFSv4] When set to the default of '1', this option
+ ensures that both the RPC level authentication
+ scheme and the NFS level operations agree to use
+ numeric uids/gids if the mount is using the
+ 'sec=sys' security flavour. In effect it is
+ disabling idmapping, which can make migration from
+ legacy NFSv2/v3 systems to NFSv4 easier.
+ Servers that do not support this mode of operation
+ will be autodetected by the client, and it will fall
+ back to using the idmapper.
+ To turn off this behaviour, set the value to '0'.
+
+ nfs.send_implementation_id =
+ [NFSv4.1] Send client implementation identification
+ information in exchange_id requests.
+ If zero, no implementation identification information
+ will be sent.
+ The default is to send the implementation identification
+ information.
+
+ nfsd.nfs4_disable_idmapping=
+ [NFSv4] When set to the default of '1', the NFSv4
+ server will return only numeric uids and gids to
+ clients using auth_sys, and will accept numeric uids
+ and gids from such clients. This is intended to ease
+ migration from NFSv2/v3.
+
+ objlayoutdriver.osd_login_prog=
+ [NFS] [OBJLAYOUT] sets the pathname to the program which
+ is used to automatically discover and login into new
+ osd-targets. Please see:
+ Documentation/filesystems/pnfs.txt for more explanations
nmi_debug= [KNL,AVR32,SH] Specify one or more actions to take
when a NMI is triggered.
debugging driver suspend/resume hooks). This may
not work reliably with all consoles, but is known
to work with serial and VGA consoles.
+ To facilitate more flexible debugging, we also add
+ console_suspend, a printk module parameter to control
+ it. Users could use console_suspend (usually
+ /sys/module/printk/parameters/console_suspend) to
+ turn on/off it dynamically.
noaliencache [MM, NUMA, SLAB] Disables the allocation of alien
caches in the slab allocator. Saves per-node memory,
nomfgpt [X86-32] Disable Multi-Function General Purpose
Timer usage (for AMD Geode machines).
+ nonmi_ipi [X86] Disable using NMI IPIs during panic/reboot to
+ shutdown the other cpus. Instead use the REBOOT_VECTOR
+ irq.
+
+ nomodule Disable module load
+
nopat [X86] Disable PAT (page attribute table extension of
pagetables) support.
arch_perfmon: [X86] Force use of architectural
perfmon on Intel CPUs instead of the
CPU specific event set.
+ timer: [X86] Force use of architectural NMI
+ timer mode (see also oprofile.timer
+ for generic hr timer mode)
+ [s390] Force legacy basic mode sampling
+ (report cpu_type "timer")
oops=panic Always panic on oopses. Default is to just kill the
process, but there is a small probability of
the default.
off: Turn ECRC off
on: Turn ECRC on.
- realloc reallocate PCI resources if allocations done by BIOS
- are erroneous.
+ realloc= Enable/disable reallocating PCI bridge resources
+ if allocations done by BIOS are too small to
+ accommodate resources required by all child
+ devices.
+ off: Turn realloc off
+ on: Turn realloc on
+ realloc same as realloc=on
+ noari do not use PCIe ARI.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.
force Enable ASPM even on devices that claim not to support it.
WARNING: Forcing ASPM on may cause system lockups.
+ pcie_hp= [PCIE] PCI Express Hotplug driver options:
+ nomsi Do not use MSI for PCI Express Native Hotplug (this
+ makes all PCIe ports use INTx for hotplug services).
+
pcie_ports= [PCIE] PCIe ports handling:
auto Ask the BIOS whether or not to use native PCIe services
associated with PCIe ports (PME, hot-plug, AER). Use
default: off.
+ printk.always_kmsg_dump=
+ Trigger kmsg_dump for cases other than kernel oops or
+ panics
+ Format: <bool> (1/Y/y=enable, 0/N/n=disable)
+ default: disabled
+
printk.time= Show timing data prefixed to each printk message line
Format: <bool> (1/Y/y=enable, 0/N/n=disable)
resume= [SWSUSP]
Specify the partition device for software suspend
+ Format:
+ {/dev/<dev> | PARTUUID=<uuid> | <int>:<int> | <hex>}
resume_offset= [SWSUSP]
Specify the offset from the beginning of the partition
slram= [HW,MTD]
+ slab_max_order= [MM, SLAB]
+ Determines the maximum allowed order for slabs.
+ A high setting may cause OOMs due to memory
+ fragmentation. Defaults to 1 for systems with
+ more than 32MB of RAM, 0 otherwise.
+
slub_debug[=options[,slabs]] [MM, SLUB]
Enabling slub_debug allows one to determine the
culprit if slab objects become corrupted. Enabling
For more information see Documentation/vm/slub.txt.
slub_min_order= [MM, SLUB]
- Determines the mininum page order for slabs. Must be
+ Determines the minimum page order for slabs. Must be
lower than slub_max_order.
For more information see Documentation/vm/slub.txt.
stacktrace [FTRACE]
Enabled the stack tracer on boot up.
+ stacktrace_filter=[function-list]
+ [FTRACE] Limit the functions that the stack tracer
+ will trace at boot up. function-list is a comma separated
+ list of functions. This list can be changed at run
+ time by the stack_trace_filter file in the debugfs
+ tracing directory. Note, this enables stack tracing
+ and the stacktrace above is not needed.
+
sti= [PARISC,HW]
Format: <num>
Set the STI (builtin display/keyboard on the HP-PARISC
threadirqs [KNL]
Force threading of all interrupt handlers except those
- marked explicitely IRQF_NO_THREAD.
+ marked explicitly IRQF_NO_THREAD.
topology= [S390]
Format: {off | on}
to facilitate early boot debugging.
See also Documentation/trace/events.txt
+ transparent_hugepage=
+ [KNL]
+ Format: [always|madvise|never]
+ Can be used to control the default behavior of the system
+ with respect to transparent hugepages.
+ See Documentation/vm/transhuge.txt for more details.
+
tsc= Disable clocksource stability checks for TSC.
Format: <string>
[x86] reliable: mark tsc clocksource as reliable, this
[USB] Start with the old device initialization
scheme (default 0 = off).
+ usbcore.usbfs_memory_mb=
+ [USB] Memory limit (in MB) for buffers allocated by
+ usbfs (default = 16, 0 = max = 2047).
+
usbcore.use_both_schemes=
[USB] Try the other device initialization scheme
if the first one fails (default 1 = enabled).
functions are at fixed addresses, they make nice
targets for exploits that can control RIP.
- emulate Vsyscalls turn into traps and are emulated
- reasonably safely.
+ emulate [default] Vsyscalls turn into traps and are
+ emulated reasonably safely.
- native [default] Vsyscalls are native syscall
- instructions.
+ native Vsyscalls are native syscall instructions.
This is a little bit faster than trapping
and makes a few dynamic recompilers work
better than they would in emulation mode.