Subversion Repositories or1k_soc_on_altera_embedded_dev_kit

AMD64 specific boot options

There are many others (usually documented in driver documentation), but

only the AMD64 specific ones are listed here.

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 on uncorrected errors, log corrected errors

                1: panic or SIGBUS on uncorrected errors, log corrected errors

                2: SIGBUS or log uncorrected errors, log corrected errors

                3: never panic or SIGBUS, log all errors (for testing only)

                Default is 1

                Can be also set using sysfs which is preferable.

   nomce (for compatibility with i386): same as mce=off

   Everything else is in sysfs now.

APICs

   apic          Use IO-APIC. Default

   noapic        Don't use the IO-APIC.

   disableapic   Don't use the local APIC

   nolapic       Don't use the local APIC (alias for i386 compatibility)

   pirq=...      See Documentation/i386/IO-APIC.txt

   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

           earlyprintk=serial[,ttySn[,baudrate]]

   The early console is useful when the kernel crashes before the

   normal console is initialized. It is not enabled by

   default because it has some cosmetic problems.

   Append ,keep to not disable it when the real console takes over.

   Only vga or serial at a time, not both.

   Currently only ttyS0 and ttyS1 are supported.

   Interaction with the standard serial driver is not very good.

   The VGA output is eventually overwritten by the real console.

Timing

  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.

  report_lost_ticks

  Report when timer interrupts are lost because some code turned off

  interrupts for too long.

  nmi_watchdog=NUMBER[,panic]

  NUMBER can be:

  1 use the IO-APIC timer for the NMI watchdog

  2 use the local APIC for the NMI watchdog using a performance counter. Note

  This will use one performance counter and the local APIC's performance

  vector.

  When panic is specified panic when an NMI watchdog timeout occurs.

  This is useful when you use a panic=... timeout and need the box

  quickly up again.

  nohpet

  Don't use the HPET timer.

Idle loop

  idle=poll

  Don't do power saving in the idle loop using HLT, but poll for rescheduling

  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

   reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old]

   bios   Use the CPU reboot vector for warm reset

   warm   Don't set the cold reboot flag

   cold   Set the cold reboot flag

   triple Force a triple fault (init)

   kbd    Use the keyboard controller. cold reset (default)

   Using warm reset will be much faster especially on big memory

   systems because the BIOS will not go through the memory check.

   Disadvantage is that not all hardware will be completely reinitialized

   on reboot so there may be boot problems on some systems.

   reboot=force

   Don't stop other CPUs on reboot. This can make reboot more reliable

   in some cases.

Non Executable Mappings

  noexec=on|off

  on      Enable(default)

  off     Disable

SMP

  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=noacpi   Don't parse the SRAT table for NUMA setup

  numa=fake=CMDLINE

                If a number, fakes CMDLINE nodes and ignores NUMA setup of the

                actual machine.  Otherwise, system memory is configured

                depending on the sizes and coefficients listed.  For example:

                        numa=fake=2*512,1024,4*256,*128

                gives two 512M nodes, a 1024M node, four 256M nodes, and the

                rest split into 128M chunks.  If the last character of CMDLINE

                is a *, the remaining memory is divided up equally among its

                coefficient:

                        numa=fake=2*512,2*

                gives two 512M nodes and the rest split into two nodes.

                Otherwise, the remaining system RAM is allocated to an

                additional node.

  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

  acpi=ht       Use ACPI boot table parsing, but don't enable ACPI

                interpreter

  acpi=force    Force ACPI on (currently not needed)

  acpi=strict   Disable out of spec ACPI workarounds.

  acpi_sci={edge,level,high,low}  Set up ACPI SCI interrupt.

  acpi=noirq    Don't route interrupts

PCI

  pci=off       Don't use PCI

  pci=conf1     Use conf1 access.

  pci=conf2     Use conf2 access.

  pci=rom       Assign ROMs.

  pci=assign-busses    Assign busses

  pci=irqmask=MASK             Set PCI interrupt mask to MASK

  pci=lastbus=NUMBER           Scan upto NUMBER busses, no matter what the mptable says.

  pci=noacpi            Don't use ACPI to set up PCI interrupt routing.

IOMMU (input/output memory management unit)

 Currently four x86-64 PCI-DMA mapping implementations exist:

   1. : use no hardware/software IOMMU at all

      (e.g. because you have < 3 GB memory).

      Kernel boot message: "PCI-DMA: Disabling IOMMU"

   2. : AMD GART based hardware IOMMU.

      Kernel boot message: "PCI-DMA: using GART IOMMU"

   3.  : Software IOMMU implementation. Used

      e.g. if there is no hardware IOMMU in the system and it is need because

      you have >3GB memory or told the kernel to us it (iommu=soft))

      Kernel boot message: "PCI-DMA: Using software bounce buffering

      for IO (SWIOTLB)"

   4.  : IBM Calgary hardware IOMMU. Used in IBM

      pSeries and xSeries servers. This hardware IOMMU supports DMA address

      mapping with memory protection, etc.

      Kernel boot message: "PCI-DMA: Using Calgary IOMMU"

 iommu=[][,noagp][,off][,force][,noforce][,leak[=]

        [,memaper[=]][,merge][,forcesac][,fullflush][,nomerge]

        [,noaperture][,calgary]

  General iommu options:

    off                Don't initialize and use any kind of IOMMU.

    noforce            Don't force hardware IOMMU usage when it is not needed.

                       (default).

    force              Force the use of the hardware IOMMU even when it is

                       not actually needed (e.g. because < 3 GB memory).

    soft               Use software bounce buffering (SWIOTLB) (default for

                       Intel machines). This can be used to prevent the usage

                       of an available hardware IOMMU.

  iommu options only relevant to the AMD GART hardware IOMMU:

                 Set the size of the remapping area in bytes.

    allowed            Overwrite iommu off workarounds for specific chipsets.

    fullflush          Flush IOMMU on each allocation (default).

    nofullflush        Don't use IOMMU fullflush.

    leak               Turn on simple iommu leak tracing (only when

                       CONFIG_IOMMU_LEAK is on). Default number of leak pages

                       is 20.

    memaper[=]  Allocate an own aperture over RAM with size 32MB<

                       (default: order=1, i.e. 64MB)

    merge              Do scatter-gather (SG) merging. Implies "force"

                       (experimental).

    nomerge            Don't do scatter-gather (SG) merging.

    noaperture         Ask the IOMMU not to touch the aperture for AGP.

    forcesac           Force single-address cycle (SAC) mode for masks <40bits

                       (experimental).

    noagp              Don't initialize the AGP driver and use full aperture.

    allowdac           Allow double-address cycle (DAC) mode, i.e. DMA >4GB.

                       DAC is used with 32-bit PCI to push a 64-bit address in

                       two cycles. When off all DMA over >4GB is forced through

                       an IOMMU or software bounce buffering.

    nodac              Forbid DAC mode, i.e. DMA >4GB.

    panic              Always panic when IOMMU overflows.

    calgary            Use the Calgary IOMMU if it is available

  iommu options only relevant to the software bounce buffering (SWIOTLB) IOMMU

  implementation:

    swiotlb=[,force]

                Prereserve that many 128K pages for the software IO

                       bounce buffering.

    force              Force all IO through the software TLB.

  Settings for the IBM Calgary hardware IOMMU currently found in IBM

  pSeries and xSeries machines:

    calgary=[64k,128k,256k,512k,1M,2M,4M,8M]

    calgary=[translate_empty_slots]

    calgary=[disable=]

    panic              Always panic when IOMMU overflows

    64k,...,8M - Set the size of each PCI slot's translation table

    when using the Calgary IOMMU. This is the size of the translation

    table itself in main memory. The smallest table, 64k, covers an IO

    space of 32MB; the largest, 8MB table, can cover an IO space of

    4GB. Normally the kernel will make the right choice by itself.

    translate_empty_slots - Enable translation even on slots that have

    no devices attached to them, in case a device will be hotplugged

    in the future.

    disable= - Disable translation on a given PHB. For

    example, the built-in graphics adapter resides on the first bridge

    (PCI bus number 0); if translation (isolation) is enabled on this

    bridge, X servers that access the hardware directly from user

    space might stop working. Use this option if you have devices that

    are accessed from userspace directly on some PCI host bridge.

Debugging

  oops=panic    Always panic on oopses. Default is to just kill the process,

                but there is a small probability of deadlocking the machine.

                This will also cause panics on machine check exceptions.

                Useful together with panic=30 to trigger a reboot.

  kstack=N      Print N words from the kernel stack in oops dumps.

  pagefaulttrace  Dump all page faults. Only useful for extreme debugging

                and will create a lot of output.

  call_trace=[old|both|newfallback|new]

                old: use old inexact backtracer

                new: use new exact dwarf2 unwinder

                both: print entries from both

                newfallback: use new unwinder but fall back to old if it gets

                        stuck (default)

Miscellaneous