DOS ain't dead

IRQ ISR IDT (DOSX)

posted by DOS386, 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 And what IDT entry does it use at all ? 8 is a Double Fault 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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Complete thread:

• IRQ ISR IDT - DOS386, 13.08.2007, 07:05 (DOSX)
  • IRQ ISR IDT - Japheth, 13.08.2007, 08:18
    • IRQ ISR IDT [2] - DOS386, 13.08.2007, 08:34
      • IRQ ISR IDT [2] - Japheth, 14.08.2007, 22:24
        • IRQ ISR IDT [3] Very weeeird results - DOS386, 16.08.2007, 10:28
          • IRQ ISR IDT [3] Very weeeird results - Japheth, 16.08.2007, 14:24
            • IRQ ISR IDT [4] Missed the point - DOS386, 17.08.2007, 00:58
              • IRQ ISR IDT [4] Missed the point - Japheth, 17.08.2007, 10:50
                • IRQ ISR IDT [5] RM ISR vs PM ISR - DOS386, 19.08.2007, 07:46
                  • IRQ ISR IDT [5] RM ISR vs PM ISR - Rugxulo, 21.08.2007, 03:16
                    • IRQ ISR IDT [5] RM ISR vs PM ISR - Japheth, 21.08.2007, 08:28
                      • IRQ ISR IDT [5] RM ISR vs PM ISR - Rugxulo, 22.08.2007, 00:13
                        • IRQ ISR IDT [5] RM ISR vs PM ISR - Steve, 23.08.2007, 13:42
                          • IRQ ISR IDT [5] RM ISR vs PM ISR - rr, 23.08.2007, 15:25
                            • IRQ ISR IDT [5] RM ISR vs PM ISR - Steve, 24.08.2007, 01:11