Too many requests for irq 11 (IRQs and APIC)
 

Distribution: SUSE 10.0
Hardware Environment: P4M UP-256MB RAM-ALI motherboard with lapic disabled in BIOS-Linux installed on external Maxtor drive connected thru' USB (Laptop - BenQ Joybook 3000 (DH3000))
Software Environment: SUSE Linux 10.0 2.6.13-15
Problem Description: My console gets flooded by message - "Too many requests for irq 11". Obviously, because several devices are using the same irq 11 !! To list out - Graphics card NVidia Geforce4, Sound card Realtek AC'97, USB Mouse, USB Storage (Maxtor 300GB drive on which linux resides), Modem PCTel HSP 56MR and IEEE 1394 firewire !! It definitely is affecting the performance of hardware, cause sometimes the mouse and keyboard do not respond and I can see my Maxtor drive working real hard.
I tried to work around by passing lapic command line option for which I get the following output-
Local APIC disabled by BIOS - You can enable it by "lapic"

I have compiled a kernel with local apic support enabled along with all the necessary options besides enabling ACPI and disabling APM. Yet, I get the same message output on my monitor. When passed the kernel parameter "lapic", it hangs and don't respond to ctrl+alt+del and have to powerdown using the poweroff button. With "lapic" option, kernel dumps a screenful of text like scanning PCI bridge, CPU etc. The last line I see is "PCI: Using configuration 1, PCI base address xxxxxxx". After that it's eternal silence.
How can I force enable Local APIC to resolve this IRQ sharing problem ?

PS: My BIOS has no option available to configure APIC !!

There are a few tools that you can use to find out how the hardware is configured, or how Linux sees the hardware. The first tool is KDE Info Center (kinfocenter). It has a very infomative listing of different views of the hardware.

Another tool that you can use in a command line shell is hwinfo. This tool will take several minutes if you invoke it without any parameters. You can invoke hwinfo with a parameter to limit its scope. The output is not very convenient for viewing interactively so you should pipe the output to a text file. You can see the list of valid parameters by entering hwinfo --help. The following command will give you a full listing.

hwinfo > t.txt

The next command will run much faster and is probably what you want to see.

hwinfo pci > t.txt

Hopefully you will see something helpful.

Neither of the tools tell me if I've got an IOPIC on my system.