1 AMD64 specific boot options
3 There are many others (usually documented in driver documentation), but
4 only the AMD64 specific ones are listed here.
8 (see the Opteron BIOS&Kernel manual for more details on the banks etc.)
10 mce=off disable machine check
11 mce=nok8 disable k8 specific features
12 mce=disable<NUMBER> disable bank NUMBER
13 mce=enable<NUMBER> enable bank number
14 mce=device Enable more machine check options in Northbridge.
15 Can be useful for device driver debugging.
16 mce=NUMBER mcheck timer interval number seconds.
17 Can be also comma separated in a single mce=
19 nomce (for compatibility with i386): same as mce=off
23 nolocalapic Don't use a local or IO-APIC. This should only
24 be needed if you have a buggy BIOS. The newer
25 kernels already turn it off by default if the
26 BIOS didn't enable the local APIC, so it will
27 be hopefully not needed.
28 Note this code path is not very well tested, you are on
31 apic Use IO-APIC. Default
33 noapic Don't use the IO-APIC.
34 Also only lightly tested.
36 pirq=... See Documentation/i386/IO-APIC.txt
40 syntax: earlyprintk=vga
41 earlyprintk=serial[,ttySn[,baudrate]]
43 The early console is useful when the kernel crashes before the
44 normal console is initialized. It is not enabled by
45 default because it has some cosmetic problems.
46 Append ,keep to not disable it when the real console takes over.
47 Only vga or serial at a time, not both.
48 Currently only ttyS0 and ttyS1 are supported.
49 Interaction with the standard serial driver is not very good.
50 The VGA output is eventually overwritten by the real console.
55 Don't use the CPU time stamp counter to read the wall time.
56 This can be used to work around timing problems on multiprocessor systems
57 with not properly synchronized CPUs. Only useful with a SMP kernel
60 Report when timer interrupts are lost because some code turned off
61 interrupts for too long.
65 0 don't use an NMI watchdog
66 1 use the IO-APIC timer for the NMI watchdog
67 2 use the local APIC for the NMI watchdog using a performance counter. Note
68 This will use one performance counter and the local APIC's performance
74 Don't do power saving in the idle loop using HLT, but poll for rescheduling
75 events. This will make the CPUs burn a lot more power, but may be useful
76 to get slightly better performance in multiprocessor benchmarks. It also
77 makes some profiling using performance counters more accurate.
81 reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old]
82 bios Use the CPU reboto vector for warm reset
83 warm Don't set the cold reboot flag
84 cold Set the cold reboto flag
85 triple Force a triple fault (init)
86 kbd Use the keyboard controller. cold reset (default)
88 Using warm reset will be much faster especially on big memory
89 systems because the BIOS will not go through the memory check.
90 Disadvantage is that not all hardware will be completely reinitialized
91 on reboot so there may be boot problems on some systems.
93 Non Executable Mappings
99 noforce (default) Don't enable by default for heap/stack/data,
100 but allow PROT_EXEC to be effective
104 Control the no exec default for 32bit processes.
105 Requires noexec=on or noexec=noforce to be effective.
108 all,on Heap,stack,data is non executable.
109 off (default) Heap,stack,data is executable
110 stack Stack is non executable, heap/data is.
111 force Don't imply PROT_EXEC for PROT_READ
112 compat (default) Imply PROT_EXEC for PROT_READ
116 nosmp Only use a single CPU
118 maxcpus=NUMBER only use upto NUMBER CPUs
120 cpumask=MASK only use cpus with bits set in mask
124 numa=off Only set up a single NUMA node spanning all memory.
129 acpi=off Don't enable ACPI
133 pci=off Don't use PCI
134 pci=conf1 Use conf1 access.
135 pci=conf2 Use conf2 access.
137 pci=assign-busses Assign busses
138 pci=irqmask=MASK Set PCI interrupt mask to MASK
139 pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says.
143 iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]]
144 size set size of iommu (in bytes)
145 noagp don't initialize the AGP driver and use full aperture.
146 off don't use the IOMMU
147 leak turn on simple iommu leak tracing (only when CONFIG_IOMMU_LEAK is on)
148 memaper[=order] allocate an own aperture over RAM with size 32MB^order.
149 noforce don't force IOMMU usage. Default.
150 force Force IOMMU for all devices.