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IRQ ISR IDT (DOSX)

posted by DOS386(R), 13.08.2007, 07:05

I'd like to install an ISR on the IRQ0 of the PIT timer. I don't want to use INT $31 to install it - my ISR has a very high priority and should run at a very high frequency and work on very low end PC's also - I want to register it in the IDT instead to avoid time waste in the DPMI host with all the routing/reflecting/chaining magic. What is the best way to do ? I don't really know what to write into the 8 bytes of IDT entry to call my ISR rather than rise a TripleFault :lol3: And what IDT entry does it use at all ? 8 is a Double Fault :confused: I'd like to minimize the HW switching magic (stack / Ring / memory model (???) ) on my IRQ as well. It's irrelevant whether my ISR "lands" in Ring0 or Ring3, it doesn't need any "API", just a minimum of registers and stack space, and can (should ?) run with interrupts disabled. Also I'd like to prohibit (in the main "thread") all interrupts except my IRQ. Should I redirect all IDT entries to a dummy IRET or are there better ways to do?

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