New interrupt stuff breaks ASUS 2 CPU system

John Baldwin jhb at
Thu Nov 6 09:23:11 PST 2003

On 06-Nov-2003 Harti Brandt wrote:
> JB>I figured out what is happenning I think.  You are getting a spurious
> JB>interrupt from the 8259A PIC (which comes in on IRQ 7).  The IRR register
> JB>lists pending interrupts still waiting to be serviced.  Try using
> JB>'options NO_MIXED_MODE' to stop using the 8259A's for the clock and see if
> JB>the spurious IRQ 7 interrupts go away.
> Ok, that seems to help. Interesting although why do these interrupts
> happen only with a larger HZ and when the kernel is doing printfs (this
> machine has a serial console). I have also not tried to disable SIO2 and
> the parallel port.

Can you also try turning mixed mode back on and using

You should get some stray IRQ 7's in the vmstat -i output as well as a few
printf's to the kernel console.


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

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