DOS ain't dead

debugxv - how to use I/O watchpoint? (Users)

posted by RayeR , CZ, 08.04.2025, 10:44

I'd need to set a breakpoint ideally on any I/O port access (without specifying address of out instruction as I don't know all the locations in debugee) - can it be achieved with debugxv /v via v86 IO traps?
I tried to set BP at specific address with out instruction of type 02 - I/O watchpoint by command
BP xxxx:yyyy 02
BP confirmed it was set
then go
but program didn't stopped at breakpoint and run till the end.
I tried to add code to set CR4.3=1 (DE) as mentioned in readme but didn't help.
If I set BP with type 00 (code) it stops as expected at given address.
Debugee is now just a simple RM COM program with few byte outs for this test but I need to debug a PM program where I need to watch out port writes. Also I may need watch RD/WRMSR...
Or any else debugger capable do this (need to be run on real HW not inside VM)?

---
DOS gives me freedom to unlimited HW access.

Complete thread:

• debugxv - how to use I/O watchpoint? - RayeR, 08.04.2025, 10:44 (Users)
  • debugxv - how to use I/O watchpoint? - Japheth, 08.04.2025, 12:30
    • debugxv - how to use I/O watchpoint? - RayeR, 08.04.2025, 14:11
      • debugxv - how to use I/O watchpoint? - Japheth, 09.04.2025, 05:53
        • debugxv - how to use I/O watchpoint? - RayeR, 09.04.2025, 11:19
          • debugxv - how to use I/O watchpoint? - Japheth, 09.04.2025, 16:33
            • debugxv - how to use I/O watchpoint? - RayeR, 09.04.2025, 20:08
            • debugxv - how to use I/O watchpoint? - RayeR, 11.04.2025, 06:14
              • debugxv - how to use I/O watchpoint? - Japheth, 11.04.2025, 09:10
                • debugxv - how to use I/O watchpoint? - RayeR, 12.04.2025, 05:59
                  • debugxv - how to use I/O watchpoint? - Japheth, 12.04.2025, 09:16
                    • debugxv - how to use I/O watchpoint? - RayeR, 12.04.2025, 15:02
                  • debugxv - how to use I/O watchpoint? - Japheth, 12.04.2025, 16:58
                  • debugxv - how to use I/O watchpoint? - rr, 12.04.2025, 18:10
                    • debugxv - how to use I/O watchpoint? - rr, 12.04.2025, 19:05
                      • debugxv - how to use I/O watchpoint? - rr, 12.04.2025, 20:11
                    • debugxv - how to use I/O watchpoint? - RayeR, 13.04.2025, 07:12
                      • debugxv - how to use I/O watchpoint? - ecm, 13.04.2025, 14:13
                        • speedsys.exe packed - ecm, 13.04.2025, 14:25
                          • speedsys.exe packed - ecm, 13.04.2025, 14:32
                            • speedsys.exe packed - RayeR, 15.04.2025, 06:43
        • debugxv - how to use I/O watchpoint? - tom, 09.04.2025, 21:06
          • debugxv - how to use I/O watchpoint? - Japheth, 10.04.2025, 13:14
            • debugxv - how to use I/O watchpoint? - tom, 10.04.2025, 18:27
    • debugxv - how to use I/O watchpoint? - RayeR, 09.04.2025, 02:58
      • debugxv - how to use I/O watchpoint? - Japheth, 09.04.2025, 05:50