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Linus Torvalds1da177e2005-04-16 15:20:36 -07001AMD64 specific boot options
2
3There are many others (usually documented in driver documentation), but
4only the AMD64 specific ones are listed here.
5
6Machine check
7
8 mce=off disable machine check
9
10 nomce (for compatibility with i386): same as mce=off
11
12 Everything else is in sysfs now.
13
14APICs
15
16 apic Use IO-APIC. Default
17
18 noapic Don't use the IO-APIC.
19
20 disableapic Don't use the local APIC
21
22 nolapic Don't use the local APIC (alias for i386 compatibility)
23
24 pirq=... See Documentation/i386/IO-APIC.txt
25
26 noapictimer Don't set up the APIC timer
27
28Early Console
29
30 syntax: earlyprintk=vga
31 earlyprintk=serial[,ttySn[,baudrate]]
32
33 The early console is useful when the kernel crashes before the
34 normal console is initialized. It is not enabled by
35 default because it has some cosmetic problems.
36 Append ,keep to not disable it when the real console takes over.
37 Only vga or serial at a time, not both.
38 Currently only ttyS0 and ttyS1 are supported.
39 Interaction with the standard serial driver is not very good.
40 The VGA output is eventually overwritten by the real console.
41
42Timing
43
44 notsc
45 Don't use the CPU time stamp counter to read the wall time.
46 This can be used to work around timing problems on multiprocessor systems
47 with not properly synchronized CPUs. Only useful with a SMP kernel
48
49 report_lost_ticks
50 Report when timer interrupts are lost because some code turned off
51 interrupts for too long.
52
53 nmi_watchdog=NUMBER[,panic]
54 NUMBER can be:
55 0 don't use an NMI watchdog
56 1 use the IO-APIC timer for the NMI watchdog
57 2 use the local APIC for the NMI watchdog using a performance counter. Note
58 This will use one performance counter and the local APIC's performance
59 vector.
60 When panic is specified panic when an NMI watchdog timeout occurs.
61 This is useful when you use a panic=... timeout and need the box
62 quickly up again.
63
64 nohpet
65 Don't use the HPET timer.
66
67Idle loop
68
69 idle=poll
70 Don't do power saving in the idle loop using HLT, but poll for rescheduling
71 event. This will make the CPUs eat a lot more power, but may be useful
72 to get slightly better performance in multiprocessor benchmarks. It also
73 makes some profiling using performance counters more accurate.
74
75Rebooting
76
77 reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old]
78 bios Use the CPU reboto vector for warm reset
79 warm Don't set the cold reboot flag
80 cold Set the cold reboot flag
81 triple Force a triple fault (init)
82 kbd Use the keyboard controller. cold reset (default)
83
84 Using warm reset will be much faster especially on big memory
85 systems because the BIOS will not go through the memory check.
86 Disadvantage is that not all hardware will be completely reinitialized
87 on reboot so there may be boot problems on some systems.
88
89 reboot=force
90
91 Don't stop other CPUs on reboot. This can make reboot more reliable
92 in some cases.
93
94Non Executable Mappings
95
96 noexec=on|off
97
98 on Enable(default)
99 off Disable
100
101SMP
102
103 nosmp Only use a single CPU
104
105 maxcpus=NUMBER only use upto NUMBER CPUs
106
107 cpumask=MASK only use cpus with bits set in mask
108
109NUMA
110
111 numa=off Only set up a single NUMA node spanning all memory.
112
113 numa=noacpi Don't parse the SRAT table for NUMA setup
114
115 numa=fake=X Fake X nodes and ignore NUMA setup of the actual machine.
116
117ACPI
118
119 acpi=off Don't enable ACPI
120 acpi=ht Use ACPI boot table parsing, but don't enable ACPI
121 interpreter
122 acpi=force Force ACPI on (currently not needed)
123
124 acpi=strict Disable out of spec ACPI workarounds.
125
126 acpi_sci={edge,level,high,low} Set up ACPI SCI interrupt.
127
128 acpi=noirq Don't route interrupts
129
130PCI
131
132 pci=off Don't use PCI
133 pci=conf1 Use conf1 access.
134 pci=conf2 Use conf2 access.
135 pci=rom Assign ROMs.
136 pci=assign-busses Assign busses
137 pci=irqmask=MASK Set PCI interrupt mask to MASK
138 pci=lastbus=NUMBER Scan upto NUMBER busses, no matter what the mptable says.
139 pci=noacpi Don't use ACPI to set up PCI interrupt routing.
140
141IOMMU
142
143 iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]][,merge]
144 [,forcesac][,fullflush][,nomerge][,noaperture]
145 size set size of iommu (in bytes)
146 noagp don't initialize the AGP driver and use full aperture.
147 off don't use the IOMMU
148 leak turn on simple iommu leak tracing (only when CONFIG_IOMMU_LEAK is on)
149 memaper[=order] allocate an own aperture over RAM with size 32MB^order.
150 noforce don't force IOMMU usage. Default.
151 force Force IOMMU.
152 merge Do SG merging. Implies force (experimental)
153 nomerge Don't do SG merging.
154 forcesac For SAC mode for masks <40bits (experimental)
155 fullflush Flush IOMMU on each allocation (default)
156 nofullflush Don't use IOMMU fullflush
157 allowed overwrite iommu off workarounds for specific chipsets.
158 soft Use software bounce buffering (default for Intel machines)
159 noaperture Don't touch the aperture for AGP.
160
161 swiotlb=pages[,force]
162
163 pages Prereserve that many 128K pages for the software IO bounce buffering.
164 force Force all IO through the software TLB.
165
166Debugging
167
168 oops=panic Always panic on oopses. Default is to just kill the process,
169 but there is a small probability of deadlocking the machine.
170 This will also cause panics on machine check exceptions.
171 Useful together with panic=30 to trigger a reboot.
172
173 kstack=N Print that many words from the kernel stack in oops dumps.
174
175Misc
176
177 noreplacement Don't replace instructions with more appropiate ones
178 for the CPU. This may be useful on asymmetric MP systems
179 where some CPU have less capabilities than the others.
180