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Diffstat (limited to 'Documentation/x86_64/boot-options.txt')
| -rw-r--r-- | Documentation/x86_64/boot-options.txt | 180 |
1 files changed, 180 insertions, 0 deletions
diff --git a/Documentation/x86_64/boot-options.txt b/Documentation/x86_64/boot-options.txt new file mode 100644 index 000000000000..44b6eea60ece --- /dev/null +++ b/Documentation/x86_64/boot-options.txt @@ -0,0 +1,180 @@ +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 + + 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 + +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. Only useful with a SMP kernel + + 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: + 0 don't use an NMI watchdog + 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. + +Rebooting + + reboot=b[ios] | t[riple] | k[bd] [, [w]arm | [c]old] + bios Use the CPU reboto 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 + + nosmp Only use a single CPU + + maxcpus=NUMBER only use upto NUMBER CPUs + + cpumask=MASK only use cpus with bits set in mask + +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=X Fake X nodes and ignore NUMA setup of the actual machine. + +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 + + iommu=[size][,noagp][,off][,force][,noforce][,leak][,memaper[=order]][,merge] + [,forcesac][,fullflush][,nomerge][,noaperture] + size set size of iommu (in bytes) + noagp don't initialize the AGP driver and use full aperture. + off don't use the IOMMU + leak turn on simple iommu leak tracing (only when CONFIG_IOMMU_LEAK is on) + memaper[=order] allocate an own aperture over RAM with size 32MB^order. + noforce don't force IOMMU usage. Default. + force Force IOMMU. + merge Do SG merging. Implies force (experimental) + nomerge Don't do SG merging. + forcesac For SAC mode for masks <40bits (experimental) + fullflush Flush IOMMU on each allocation (default) + nofullflush Don't use IOMMU fullflush + allowed overwrite iommu off workarounds for specific chipsets. + soft Use software bounce buffering (default for Intel machines) + noaperture Don't touch the aperture for AGP. + + swiotlb=pages[,force] + + pages Prereserve that many 128K pages for the software IO bounce buffering. + force Force all IO through the software TLB. + +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 that many words from the kernel stack in oops dumps. + +Misc + + noreplacement Don't replace instructions with more appropiate ones + for the CPU. This may be useful on asymmetric MP systems + where some CPU have less capabilities than the others. + |