LXR linux-old/Documentation/x86

   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
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 153