usb/74989: (regression) Lost USB support between 5.2.1-RELEASE and 5.3-RELEASE on K7T266 Pro2.

John Baldwin jhb at
Thu Apr 14 23:35:48 PDT 2005

On Thursday 14 April 2005 06:41 am, Julien Gabel wrote:
> Hello,
> I made some progress here. After playing with BIOS settings, i am now
> able to:
>  - Boot with ACPI enable (shutdown -p works as expected now);
>  - Use USB devices.
> In order to do that, i had to totally disable "APIC Function" in the
> BIOS. With "APIC Function" enabled, neither version 1.4 nor 1.1 of the
> "MPS Table Version" settings solved my problem.
> So, although i meed to disable "APIC Function", all seems to works
> correctly together: ACPI support and USB support. As a side note, i
> did not encountered anymore the interrupt storm on the uhci USB host
> controller driver.
> Maybe can someone explain me what may be wrong with "APIC Function",
> and if there is some drawbacks to disable it (or what is the purpose
> of this setting)?

APIC is used to route interrupts differently.  You can also disable it from 
the loader with 'hint.apic.0.disabled=1'.  I've looked at your dmesg's, and 
the problem is that in the ACPI case the IRQ 10 that your USB controllers are 
using is configured as an ISA IRQ (edge/high).  For now you can either 
disable APIC or ACPI as a workaround until I figure out a better solution.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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