DOS ain't dead

User exception handler in C (Developers)

posted by Rugxulo , Usono, 23.08.2020, 17:32

> No. SMSW is correct.
>
> 1) LMSW is privilegged, SMSW not

Those date from 286 era, no? So before CR0 was made user-accessible.

> 2) SMSW AX is MOV AX,CR0 and LMSW AX is MOV CR0,AX

Your "mov eax,0" confused me. Apparently you're clearing the top bits of the return value in advance, right?

FPC started as a 386 compiler for DOS (GO32V1), so this is probably some relic of that history. In FPC's case, I don't think CR0 is very useful overall, at least not directly.

Complete thread:

• User exception handler in C - RayeR, 24.07.2020, 13:15 (Developers)
  • User exception handler in C - Japheth, 24.07.2020, 18:07
  • User exception handler in C - Rugxulo, 24.07.2020, 18:39
  • User exception handler in C - tkchia, 24.07.2020, 20:47
    • User exception handler in C - RayeR, 30.07.2020, 13:18
      • User exception handler in C - tom, 30.07.2020, 23:54
        • User exception handler in C - RayeR, 01.08.2020, 02:13
          • User exception handler in C - Laaca, 16.08.2020, 21:27
            • User exception handler in C - Laaca, 16.08.2020, 22:38
              • User exception handler in C - Rugxulo, 17.08.2020, 22:35
                • User exception handler in C - marcov, 18.08.2020, 12:23
                  • User exception handler in C - Laaca, 18.08.2020, 20:15
                    • User exception handler in C - Rugxulo, 19.08.2020, 19:44
                      • User exception handler in C - Laaca, 19.08.2020, 21:50
                        • User exception handler in C - Rugxulo, 23.08.2020, 17:32
                          • User exception handler in C - Japheth, 23.08.2020, 20:36
            • User exception handler in C - Rugxulo, 17.08.2020, 22:26
            • User exception handler in C - tkchia, 19.08.2020, 18:52
              • User exception handler in C - marcov, 20.08.2020, 00:00
                • User exception handler in C - Laaca, 20.08.2020, 15:31
      • User exception handler in C - tkchia, 31.07.2020, 19:36
        • User exception handler in C - RayeR, 01.08.2020, 02:16
  • User exception handler in C - Guti, 27.07.2020, 08:22