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Stephen RC
Asked: 2011-07-07 16:17:51 +0800 CST

What do the different Boot Options mean? (i.e. acpi=off, noapic, nolapic, etc)

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I've been having issues installing 11.04 on my new laptop, the solution was to enable any of these boot options:

  • acpi=off
  • noapic
  • nolapic

But, what do these options actually do?

What sort of problems are there in enabling them?
i.e. can they cause hardware problems (like fans not running causing system overheating).

boot

2 Answers

  1. Best Answer

    In general, such boot parameters are not needed unless there is a problem with your BIOS and how it handles these standards, or it just might be old enough where these standards were not fully implemented properly.

    ACPI (Advanced Configuration and Power Interface) is a standard for handling power management. Older systems may not support ACPI full, so sometimes it helps to give the kernel a hint to not use it. "acpi=off"

    APIC (Advanced Programmable Interrupt Controller) is a kind of feature found on newer systems. The "local" version is called "LAPIC". What this controller can do is be set up to generate and handle interrupts, a signal the hardware uses to pass messages. Again, some implementations of APIC can have problems on older system, and so it is useful to disable it. "noapic" and "nolapic".

    Sometimes the APIC is working, but it slows things down by getting in the middle of messages being passed around. This can mess with audio and video processing, for example. Folks might disable it for that reason as well.

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  2. no problem for the hardware I think, as setting those functions off doesn't actually turn them off, but sets who implements them - 'off' in bios would mean that would be the kernel

    what actually impacts the cooling fans I think was 'noapm' or 'apm=off' (advanced power management), but turning that off would mean cooling fans work in full speed all the time, as the 'advanced' part is actually slowing them down when system cool enough

    setting those things permanently was doen by writing them in the grub file in /etc/default (usually) and after that rebuilding grub with 'update-grub' or 'grub-mkconfig' (grub2 instead of grub might be needed sometimes) depending on the system

    generally it goes like 'the smaller the laptop - the bigger probability it will need them and more of them' ;)

    pnpbios=off might also help (it's for plug n play)

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