Machine check
mce=off disable machine check
+ mce=bootlog Enable logging of machine checks left over from booting.
+ Disabled by default on AMD because some BIOS leave bogus ones.
+ If your BIOS doesn't do that it's a good idea to enable though
+ to make sure you log even machine check events that result
+ in a reboot. On Intel systems it is enabled by default.
+ mce=nobootlog
+ Disable boot machine check logging.
+ mce=tolerancelevel (number)
+ 0: always panic, 1: panic if deadlock possible,
+ 2: try to avoid panic, 3: never panic or exit (for testing)
+ default is 1
+ Can be also set using sysfs which is preferable.
nomce (for compatibility with i386): same as mce=off
APICs
apic Use IO-APIC. Default
- Unless you have an NVidia or VIA/Uniprocessor board.
- Then it defaults to off.
noapic Don't use the IO-APIC.
pirq=... See Documentation/i386/IO-APIC.txt
+ noapictimer Don't set up the APIC timer
+
+ no_timer_check Don't check the IO-APIC timer. This can work around
+ problems with incorrect timer initialization on some boards.
+
+ apicmaintimer Run time keeping from the local APIC timer instead
+ of using the PIT/HPET interrupt for this. This is useful
+ when the PIT/HPET interrupts are unreliable.
+
+ noapicmaintimer Don't do time keeping using the APIC timer.
+ Useful when this option was auto selected, but doesn't work.
+
+ apicpmtimer
+ Do APIC timer calibration using the pmtimer. Implies
+ apicmaintimer. Useful when your PIT timer is totally
+ broken.
+
+ disable_8254_timer / enable_8254_timer
+ Enable interrupt 0 timer routing over the 8254 in addition to over
+ the IO-APIC. The kernel tries to set a sensible default.
+
Early Console
syntax: earlyprintk=vga
notsc
Don't use the CPU time stamp counter to read the wall time.
This can be used to work around timing problems on multiprocessor systems
- with not properly synchronized CPUs. Only useful with a SMP kernel
+ with not properly synchronized CPUs.
report_lost_ticks
Report when timer interrupts are lost because some code turned off
This is useful when you use a panic=... timeout and need the box
quickly up again.
+ nohpet
+ Don't use the HPET timer.
+
Idle loop
idle=poll
event. This will make the CPUs eat a lot more power, but may be useful
to get slightly better performance in multiprocessor benchmarks. It also
makes some profiling using performance counters more accurate.
+ Please note that on systems with MONITOR/MWAIT support (like Intel EM64T
+ CPUs) this option has no performance advantage over the normal idle loop.
+ It may also interact badly with hyperthreading.
Rebooting
reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old]
bios Use the CPU reboto vector for warm reset
warm Don't set the cold reboot flag
- cold Set the cold reboto flag
+ cold Set the cold reboot flag
triple Force a triple fault (init)
kbd Use the keyboard controller. cold reset (default)
Disadvantage is that not all hardware will be completely reinitialized
on reboot so there may be boot problems on some systems.
+ reboot=force
+
+ Don't stop other CPUs on reboot. This can make reboot more reliable
+ in some cases.
+
Non Executable Mappings
noexec=on|off
- on Enable
+ on Enable(default)
off Disable
- noforce (default) Don't enable by default for heap/stack/data,
- but allow PROT_EXEC to be effective
-
- noexec32=opt{,opt}
-
- Control the no exec default for 32bit processes.
- Requires noexec=on or noexec=noforce to be effective.
-
- Valid options:
- all,on Heap,stack,data is non executable.
- off (default) Heap,stack,data is executable
- stack Stack is non executable, heap/data is.
- force Don't imply PROT_EXEC for PROT_READ
- compat (default) Imply PROT_EXEC for PROT_READ
SMP
cpumask=MASK only use cpus with bits set in mask
+ additional_cpus=NUM Allow NUM more CPUs for hotplug
+ (defaults are specified by the BIOS, see Documentation/x86_64/cpu-hotplug-spec)
+
NUMA
numa=off Only set up a single NUMA node spanning all memory.
+ numa=noacpi Don't parse the SRAT table for NUMA setup
+
+ numa=fake=X Fake X nodes and ignore NUMA setup of the actual machine.
+
+ numa=hotadd=percent
+ Only allow hotadd memory to preallocate page structures upto
+ percent of already available memory.
+ numa=hotadd=0 will disable hotadd memory.
ACPI
interpreter
acpi=force Force ACPI on (currently not needed)
+ acpi=strict Disable out of spec ACPI workarounds.
+
+ acpi_sci={edge,level,high,low} Set up ACPI SCI interrupt.
+
+ acpi=noirq Don't route interrupts
+
PCI
pci=off Don't use PCI
pci=assign-busses Assign busses
pci=irqmask=MASK Set PCI interrupt mask to MASK
pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says.
+ pci=noacpi Don't use ACPI to set up PCI interrupt routing.
IOMMU
pages Prereserve that many 128K pages for the software IO bounce buffering.
force Force all IO through the software TLB.
+
+Debugging
+
+ 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.
+
+ kstack=N Print that many words from the kernel stack in oops dumps.
+
+ pagefaulttrace Dump all page faults. Only useful for extreme debugging
+ and will create a lot of output.
+
+Misc
+
+ noreplacement Don't replace instructions with more appropriate ones
+ for the CPU. This may be useful on asymmetric MP systems
+ where some CPU have less capabilities than the others.
git://git.onelab.eu / linux-2.6.git / blobdiff