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IDT and PIC question
Posted: Fri Nov 15, 2002 11:16 pm
by neowert
When you go into pmode, do you need to remap the PIC to int 32 and above because there are more cpu exceptions in pmode than real mode?
Re:IDT and PIC question
Posted: Sat Nov 16, 2002 9:31 am
by Curufir
Yes, the exceptions/reserved interrupts are at 0->31 the initial mapping of the PIC is within this range, so they clash.
It's not obligatory to remap the PICs, but it saves having to figure out wether an exception has occurred or it was just a normal interrupt. You have 256 interrupts at your disposal so remapping to leave the exceptions the first 32 and the IRQs somewhere else is not a big loss.
Curufir
Re:IDT and PIC question
Posted: Wed Nov 20, 2002 10:44 am
by Tom
I've noticed that sometimes the CPU tripple faults when you DON'T remap the IRQs...at least with the IDT I had.