DOS ain't dead

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

posted by alexfru, USA, 21.01.2023, 17:13

> So it does look like only ring 0 code can iret into Virtual
> 8086 mode. Another interesting fact is that an iret to V86
> mode will also pop additional registers from the ring 0 stack.

Yep. It's similar to transferring control between different CPLs in regular protected mode.

> (Another way I can think of to transition from ring 3 PM to V86 mode, is to
> jump to a task gate or a TSS which has been set up for V86 mode. But in
> this case the ring 0 supervisor would need to have set up the TSS
> beforehand, to allow such a thing...)

Yes, this too.

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