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> DOS > DPMI help |
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CandyMan 02 Jun 2015, 16:08
when you turned off paging in CR0 and the error persists it mean that there is a general protection fault instead of paging fault
perhaps a segment limit was exceeded Code:
mov esi,0x000F0000
mov eax,[fs:esi]
Code:
mov esi,0x000F0000
mov eax,ds
lsl eax,ax
cmp eax,esi
mov eax,0
ja @F
mov al,[esi]
@@:
_________________ smaller is better |
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02 Jun 2015, 16:08 |
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ring0 03 Jun 2015, 10:44
Hello Candyman
I did load and check the segment limit as suggested - it is 4GB. Page fault is what is reported by the DPMI host. Could someone who uses DPMI please respond? |
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03 Jun 2015, 10:44 |
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DOS386 23 Jun 2015, 17:23
> Could someone who uses DPMI please respond?
Give complete info ... complete code, and shot of the crash screen from HDPMI32. |
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23 Jun 2015, 17:23 |
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ring0 27 Jun 2015, 08:38
Hello DOS386,
Sorry to take some time to respond. Please find attached source code - just a small variation from the FASM example useDPMI. The line which causes the error is marked in the source - near to the bottom of the code. I am using CWSDPMI, specifically CWSDPR0.exe with FreeDOS - no drivers loaded. I do not have HDPMI32 - unable to download from Japeth. Screen dump - I will just tell you what it says: Hello from protected mode! Page Fault cr2=0011e670 @ eip=17; flags=3246 eax=0000,0200 ebx=0002,0064 ecx=0000,ffff edx=bfe9,ff0a esi=000f,0000 edi=0000,0064 ebp=0000,091e esp=0000,1002 cs=ac ds=b4 es=b4 fs=b4 gs=b4 ss=a4 error=0000
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27 Jun 2015, 08:38 |
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CandyMan 27 Jun 2015, 14:16
in HDPMI32 everything is acting correctly, and in 32rtm the mistake still is appearing
in CR2 there is linear address of page fault (0xF0000+(Main shl 4)) is above 1MB JAPHETH's side not respond, try download HDPMI by this address: http://web.archive.org/web/www.japheth.de _________________ smaller is better |
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27 Jun 2015, 14:16 |
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ring0 27 Jun 2015, 22:51
Hello CandyMan
Thankyou for taking the time to test under HDPMI and thankyou for the link - I shall get HDPMI but I would really like to know about the issue with CWSDPMI if anyone here knows the answer please share. |
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27 Jun 2015, 22:51 |
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DOS386 12 Sep 2015, 11:18
> would really like to know
0. CWSDPR0.exe gives you Ring0, but paging is still on (it is always on with CWSDPMI), and you still risk PF's 1. segment limit is 4 GiO, so you can't get a GPF due to segment limit 2. you simply forgot to hog your memory before reading from it 
3. if you want to access physical memory, you must map it before 4. there is no official way to hog physical memory with D.P.M.I. |
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12 Sep 2015, 11:18 |
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