DOS ain't dead

Can a DPMI program enter V86M with iretd instruction? (DOSX)

posted by ecm  , Düsseldorf, Germany, 20.01.2023, 17:52

I played around with lDebugX and the dpmimini example in my local Linux box's dosemu2, and found that an iretd (or o32 iret) which sets the VM flag apparently tries to load a stack pointer from the PM stack, I get a Stack fault if this cannot succeed. In case it does succeed, the DPMI host apparently returns a General protection fault.

Is it possible to enter V86M using just iretd in DPMI protected mode? If yes: How much does the DPMI host get confused by this, and can it avoid that?

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l

Complete thread:

• Can a DPMI program enter V86M with iretd instruction? - ecm, 20.01.2023, 17:52
  • Can a DPMI program enter V86M with iretd instruction? - alexfru, 21.01.2023, 03:35
    • Can a DPMI program enter V86M with iretd instruction? - ecm, 21.01.2023, 09:03
      • Can a DPMI program enter V86M with iretd instruction? - alexfru, 21.01.2023, 09:50
      • Can a DPMI program enter V86M with iretd instruction? - tkchia, 21.01.2023, 14:06
        • Can a DPMI program enter V86M with iretd instruction? - alexfru, 21.01.2023, 17:13