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
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
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
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=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
acpi=off Don't enable ACPI
kstack=N Print that many words from the kernel stack in oops dumps.
-Misc
+ pagefaulttrace Dump all page faults. Only useful for extreme debugging
+ and will create a lot of output.
- noreplacement Don't replace instructions with more appropiate ones
- for the CPU. This may be useful on asymmetric MP systems
- where some CPU have less capabilities than the others.
+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.