DOS ain't dead

TripleFault [3] (DOSX)

posted by DOS386, 16.08.2007, 10:09

> > Is there a way to test whether the IDT is writable before actually
> writing
> > ? VESAMTRR seems to do so ( "Ring0 is inaccessible" , no crash ) but
> > couldn't find the test in the source
>
> VESAMTRR doesn't need write access to GDT, just read-access. And it is
> easy to find since int 31h, ax=203h | ax=212h are the only - legal - ways
> to set an exception handler in DPMI.

Thanks ... this is documented this way and I write into IDT only ... but VESAMTRR seems not to use INT $31 to deal with exceptions ... it seems to give up because the GDT/LDT search fails somewhat

But is there a good way to verify accessibility or writability of the IDT (or just any address), besides the touch-and-get-burnt strategy ?

---
This is a LOGITECH mouse driver, but some software expect here
the following string:*** This is Copyright 1983 Microsoft ***

Complete thread:

• TripleFault - DOS386, 13.08.2007, 06:46 (DOSX)
  • TripleFault - Japheth, 13.08.2007, 08:24
    • TripleFault [2] - DOS386, 13.08.2007, 08:37
      • TripleFault [2] - Japheth, 13.08.2007, 11:41
        • TripleFault [3] - DOS386, 16.08.2007, 10:09
          • TripleFault [3] - Japheth, 17.08.2007, 10:56
            • TripleFault [4] | 80686 -> 80486 -> 80386 -> 80286 !?!? - DOS386, 19.08.2007, 07:36
              • TripleFault [4] | 80686 -> 80486 -> 80386 -> 80286 !?!? - Rugxulo, 21.08.2007, 03:04
                • TripleFault [4] | 80686 -> 80486 -> 80386 -> 80286 !?!? - Matjaz, 21.08.2007, 11:07
                  • TripleFault [4] | 80686 -> 80486 -> 80386 -> 80286 !?!? - Rugxulo, 22.08.2007, 00:19
                    • TripleFault [5] | 80686 -> 80486 -> 80386 -> 80286 !?!? - DOS386, 25.08.2007, 02:31
                      • TripleFault [5] | 80686 -> 80486 -> 80386 -> 80286 !?!? - Rugxulo, 25.08.2007, 03:15
            • TripleFault [6] VERxx's NOP - DOS386, 31.08.2007, 07:09
              • TripleFault [7] VERxx's NOP | Crash via Ports - DOS386, 02.09.2007, 12:00