npxintr from nowhere

[Bruce Evans]

On Sun, 22 May 2005, Vaibhave Agarwal wrote:

> I was writing some code at the ethernet layer,
> mainly changing the if_ethersubr.c for my work.
>
> I am not using any FP instructions in my code.
> But while running, my kernel crashes and gives the following panic msg:
> npx is the Floating point unit (fpu).
>
> ----------------------------------
> npxintr: npxproc = 0 , currproc = 0, npx_exists = 1
> panic: npxintr from nowhere
> ---------------------------------
> ...
>
> Has anybody ever got such message or they know the fix for it.
> I was not able to trace the error...even using kernel debug corefiles.

If you have a system newer than a 486SX, then npx interrupts shouldn't
be used for anything except to probe that not using them works.  It
is barely possible that a bug in turning off npx interrupts after the
probe results in one being delivered much later (there have been bugs
in this area).

If it was a real npx interrupt, then the address of the FP instruction
that caused it should be in the FPU state in the kernel dump.

Bruce