1AMD64 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(see the Opteron BIOS&Kernel manual for more details on the banks etc.)
9
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=
18
19   nomce (for compatibility with i386): same as mce=off
20
21APICs
22
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
29		 your own.
30
31   apic		 Use IO-APIC. Default
32
33   noapic	 Don't use the IO-APIC.
34		 Also only lightly tested.
35
36   pirq=...	 See Documentation/i386/IO-APIC.txt
37
38Early Console
39
40   syntax: earlyprintk=vga
41           earlyprintk=serial[,ttySn[,baudrate]]
42
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.
51
52Timing
53
54  notsc
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
58
59  report_lost_ticks
60  Report when timer interrupts are lost because some code turned off
61  interrupts for too long.
62
63  nmi_watchdog=NUMBER
64  NUMBER can be:
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
69  counter vector.
70
71Idle loop
72
73  idle=poll
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.
78
79Rebooting
80
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)
87
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.
92
93Non Executable Mappings
94
95  noexec=on|off
96
97  on      Enable
98  off     Disable
99  noforce (default) Don't enable by default for heap/stack/data,
100          but allow PROT_EXEC to be effective
101
102  noexec32=opt{,opt}
103
104  Control the no exec default for 32bit processes.
105  Requires noexec=on or noexec=noforce to be effective.
106
107  Valid options:
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
113
114SMP
115
116  nosmp	Only use a single CPU
117
118  maxcpus=NUMBER only use upto NUMBER CPUs
119
120  cpumask=MASK   only use cpus with bits set in mask
121
122NUMA
123
124  numa=off	Only set up a single NUMA node spanning all memory.
125
126
127ACPI
128
129  acpi=off	Don't enable ACPI
130
131PCI
132
133  pci=off	Don't use PCI
134  pci=conf1	Use conf1 access.
135  pci=conf2	Use conf2 access.
136  pci=rom	Assign ROMs.
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.
140
141IOMMU
142
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.
151
152
153