On Mon, Mar 06, 2000 at 11:14:13AM -0800, B. James Phillippe wrote:
> Sorry for this somewhat OT question - I'll try to be brief. I have always
> noticed that on x86 Linux boxes, IRQ 13 is for the FPU and is always "1" (I
> assume this is from probing or testing at bootup). This value never seems
> to change, so again I will assume that it is only used to signal FPU
> errors. There is no "fpu IRQ" on my Alpha, obviously it has an FPU as
> well. Is it's existance on the PC just some lame legacy issue?
Normally, an FPU exception is reported as an exception to the CPU. Some old
ix86 boards did hardwire this also to IRQ 13. The kernel tests this on
bootup and therefore you see the 1. If you produce FPU excpetions normally,
you should see exception 16 instead, IIRC. However, as long as noe occured,
you won't see it vai /proc/interrupts.
I don't know how FPU exceptions on the AXP are reported ...
-- Kurt Garloff <garloff@suse.de> Eindhoven, NL GPG key: See mail header, key servers Linux kernel development SuSE GmbH, Nuernberg, FRG SCSI, Security
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