Messages in this thread | | | Date | Mon, 06 Mar 2000 17:29:50 -0800 | From | "H. Peter Anvin" <> | Subject | Re: [OT] fpu IRQ x86-ism |
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Riley Williams wrote: > > Hi Peter. > > >> 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? > > > Yup. It isn't even used to signal FPU errors on 486+ PCs. > > Does that mean it's available for use by other hardware, or is > that prohibited by other considerations? >
It's not -- there is no wire that can be used to raise IRQ 13 from any other device.
-hpa
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