DOS ain't dead - For Rayer - shared resources between DOS and WinXP

For Rayer - shared resources between DOS and WinXP (Announce)

posted by Japheth , Germany (South), 11.07.2008, 09:30

> I tried a small experiment in DJGPP.
> I made a simple program which dumps CS, DS, SS decriptors and show its
> bases. I run it under NTVDM and the result was:
>
> CS: 1A7h, base = 029E0000h, limit = 9FFFFh, granularity = 1B> DS: 1AFh, base = 029E0000h, limit = 9FFFFh, granularity = 1B > SS: 1AFh, base = 029E0000h, limit = 9FFFFh, granularity = 1B > DOS_DS: 1AFh, base = 00000000h, limit = 0010Fh, granularity = 4096B > MSGPTR: 118E0h
>
> I have placed magic string at offset 118E0.
> Parallel with this program I launched Read & Write utility and look at
> physical
> assress equal to base+offset but no magic string there. I searched through
> phys memory and found it much higher somewhere over 50000000, 60000000 and
> more in some instances. Hm is it messed up due to paging?

Yes, addresses in GDT/LDT are linear addresses. Physical addresses are "used" by CR3, page dirs and page tables.

> Normally I would
> expect that segment descriptor base address is physical address... So seems
> a VDD is only possible way (except that damn ramdisk :)

Why do you suddenly talk about physical addresses? You won't be able to get physical addresses with a VDD.

---
MS-DOS forever!

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Complete thread:

For Rayer - shared resources between DOS and WinXP - Laaca, 05.07.2008, 10:08 (Announce)
- For Rayer - shared resources between DOS and WinXP - Japheth, 05.07.2008, 11:27
  - For Rayer - shared resources between DOS and WinXP - RayeR, 06.07.2008, 13:26
    - For Rayer - shared resources between DOS and WinXP - Japheth, 07.07.2008, 09:19
      - For Rayer - shared resources between DOS and WinXP - RayeR, 08.07.2008, 14:02
        For Rayer - shared resources between DOS and WinXP - Japheth, 08.07.2008, 17:08
        For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 02:53
        For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 09:30
        For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 11:18
        For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 11:38
        For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 14:12
        For Rayer - shared resources between DOS and WinXP - Japheth, 11.07.2008, 20:39
        For Rayer - shared resources between DOS and WinXP - RayeR, 16.07.2008, 15:51
        For Rayer - shared resources between DOS and WinXP - Japheth, 17.07.2008, 08:20
        For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 12:25
        For Rayer - shared resources between DOS and WinXP - Japheth, 17.07.2008, 13:38
        For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 14:05
        For Rayer - shared resources between DOS and WinXP - Rugxulo, 17.07.2008, 14:35
        For Rayer - shared resources between DOS and WinXP - RayeR, 17.07.2008, 18:55
        For Rayer - shared resources between DOS and WinXP - Rugxulo, 18.07.2008, 13:50
        For Rayer - shared resources between DOS and WinXP - RayeR, 22.07.2008, 10:24
        For Rayer - shared resources between DOS and WinXP - Rugxulo, 23.07.2008, 00:51
        For Rayer - shared resources between DOS and WinXP - RayeR, 23.07.2008, 16:56
        For Rayer - shared resources between DOS and WinXP - Rugxulo, 24.07.2008, 07:06
        For Rayer - shared resources between DOS and WinXP - Rugxulo, 23.07.2008, 01:00
- For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 23:04
  - For Rayer - shared resources between DOS and WinXP - RayeR, 11.07.2008, 23:19
- For Rayer - shared resources between DOS and WinXP - ho1459, 13.07.2008, 08:40