DebuggingIRQProblems

Revision 5 as of 2005-12-18 01:42:12

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Debugging IRQ Problems

What is an IRQ

An IRQ is a way for hardware to talk the Operating System, in this case Ubuntu. It does this by sending an interupt request, hence IRQ. Sometimes these interupts get mixed up and the message does not get through. For example if two devices use the same IRQ, and the driver is not written to handle this, it may end up processing an IRQ for which it wasn't supposed to. Modern device drivers typically resolve this themselves, but sometimes they need help.

A BIOS is a Basic Input Output System. This starts your computer for you and allows you to configure devices before the computer is booted. Most times the BIOS can be accessed by pressing ESC, Del or F2 when you first power on the computer. If you have no experience with the BIOS, you do not want to change any of the settings without the help of knowledgable person.

How do I know there is a problem?

The following are some symptoms which may indicate an IRQ-related problem:

  • Hardware devices being detected, but not functional (sound, network, etc.)
  • Problems using two hardware devices at the same time, or only when devices are connected at the same time.
  • System hangs (lockup).

What do I do?

If you think you may be experiencing such a problem, try these steps in order:

  • Boot the system with the noapic boot parameter

  • Boot the system with the pci=routeirq

  • Boot the system with the pci=noacpi boot parameter

  • Boot the system with the acpi=off boot parameter

Each of these options disables a feature of Ubuntu. NOTE: These options are architecture specific. They mainly apply to i386 and amd64.

To add these options to the boot command line, use the edit option in the grub boot menu.

If that fails

1) If you have a BIOS conflict be sure to check your BIOS settings to see if some of the items can be turned off temporarily (serial ports etc).

2) Try changing the order of the cards in your PC. There have been cases where the BIOS will only work with certain types of cards in certain slots.

3) If you are experiencing system panics or hangs, follow the instructions at DebuggingSystemCrash

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