Message-ID:	<01BDF2E4.8F657C20@PLUM.engr.rendition.com>
From:	Jay Tseng <jay DOT tseng AT rendition DOT com>
To:	"'djgpp AT delorie DOT com'" <djgpp AT delorie DOT com>
Cc:	"'jay DOT tseng AT rendition DOT com'" <jay DOT tseng AT rendition DOT com>
Subject:	help needed on DPMI and DOS extender
Date:	Thu, 8 Oct 1998 17:53:29 -0700
MIME-Version:	1.0
X-MIME-Autoconverted:	from quoted-printable to 8bit by delorie.com id UAA05415
Reply-To:	djgpp AT delorie DOT com

Hi,

Thanks for the attention.

I am writing C code which called DPMI service thru int386(31h,..)  to access local memory residing in  the graphics card. The code is compiled  under gcc v2.01 without any switch except -o. General Protection Fault happens when accessing  local (graphic) memory, even given the fact that  I have mapped the local memory to system memory using int386(31h,..). I think that the mapping did not  do what it is supposed to do since it needs DOS extender which I did not supply. I guess my questions are:
* What's the difference between DPMI and go32-v2.exe?
* When to use them and how? For example, how can we invoke go32-v2, from where to invoke it, can I link it with the c object codes, and  how DPMI is used?
* What kind of  configuration settings in autoexec.bat and config.sys are needed? Any other things that I should be aware of  regarding the DOS extender?
* Any reference (e.g. books ) that I can access?

Thanks.

The following are environ.lst,  autoexec.bat, config.sys, and run time error message.

=========================== environ.lst =========================================
GO32_V2_DEBUG=y
COMSPEC=C:\COMMAND.COM
PROMPT=$p$g
PATH=C:\NFS;C:\USR\LOCAL\BIN;C:\DJGPP\BIN;C:\VI;C:\;C:\BIN;C:\DOS;C:\UNIX;C:\TESTS2;C:\4DOS;C:\DOSSCRIP
TZ=PST8PDT
NFSLANG=USA
NFSPATH=C:\NFS
DJGPP=c:\DJGPP\DJGPP.ENV
TCL_LIBRARY=c:\USR\LOCAL\LIB\TCL
TK_LIBRARY=c:\USR\LOCAL\LIB\TK
HOME=C:\
DOS4G=quiet
VDT_NOVERITE=1
MEMBASE=0XFB000000
IOBASE=0XE400

========================= autoexec.bat ========================================
REM This line loads McAfee VSHIELD
REM C:\MCAFEE\VIRUSCAN\VSHIELD
rem C:\WINDOWS\SMARTDRV.EXE
rem C:\DOS\SMARTDRV.EXE /E:8192 /B:4096 4096 1024
@ECHO OFF
VERIFY ON
PROMPT $p$g
PATH C:\NFS;c:\usr\local\bin;c:\djgpp\bin;c:\vi;C:\;C:\BIN;C:\DOS;C:\UNIX;C:\TESTS2;c:\4dos;c:\dosscrip
rem SET TEMP=C:\WINDOWS\TEMP
rem SET LMOUSE=C:\MOUSE
rem C:\MOUSE\MOUSE.EXE
c:\lanman\netbind
REM *** The following block of lines was added by PC-NFS Configuration.***
SET TZ=PST8PDT
SET NFSLANG=USA
SET NFSPATH=C:\NFS
rem SET TN_DIR=C:\NFS\TELNET
rem -------------------------------------
set DJGPP=c:\DJGPP\DJGPP.ENV
rem -------------------------------------
SET TCL_LIBRARY=c:\USR\LOCAL\LIB\TCL
SET TK_LIBRARY=c:\USR\LOCAL\LIB\TK
SET HOME=C:\
C:\NFS\PRT *
C:\NFS\NET INIT
REM C:\nfs\net login *
REM ***
doskey
set DOS4G=quiet
rem for verite vga mode testing only
set vdt_noverite=1
\tests2\verbase
REM This line reloads McAfee VSHIELD after any network or keyboard drivers
rem C:\MCAFEE\VIRUSCAN\VSHIELD /reconnect
mode mono

============  config.sys ====================================================
buffers=15,0
shell=c:\command.com c:\ /p /e:800
rem DEVICE=C:\DOS\SETVER.EXE
DEVICE=C:\DOS\HIMEM.SYS /testmem:off
rem DEVICE=C:\DOS\emm386.exe noems
DEVICE=C:\DOS\ansi.sys
DOS=HIGH,UMB
FILES=30
rem ----------- djgpp ------------------------ 
set GO32_v2_DEBUG=y
rem ------------------------------------------
REM *** The following block of lines was added by PC-NFS Configuration.***
LASTDRIVE=Z
DEVICEhigh=C:\NFS\PCNFS.SYS /C^
DEVICEhigh=C:\NFS\SOCKDRV.SYS
DEVICE=c:\lanman\PROTMAN.SYS /I:c:\lanman
DEVICE=c:\lanman\NFS-NDIS.SYS
DEVICE=c:\lanman\NE2000.DOS
REM ***
REM DEVICE=C:\WINDOWS\SMARTDRV.EXE /DOUBLE_BUFFER
REM DEVICE=C:\WINDOWS\IFSHLP.SYS
rem device=C:\dos\display.sys con=(ega2,,1)
STACKS=9,256



===========  Error message during run time ==================================

Exiting due to signal SIGSEGV
General Protection Fault at eip=0000eb28
eax=00000022 ebx=fb009000 ecx=00000000 edx=00000022 esi=00009000 edi=00001d27
ebp=0007e8a8 esp=0007e884 program=a:\AA.EXE
cs: sel=00a7  base=10000000  limit=0008ffff
ds: sel=00af  base=10000000  limit=0008ffff
es: sel=00af  base=10000000  limit=0008ffff
fs: sel=008f  base=00028300  limit=0000ffff
gs: sel=00bf  base=00000000  limit=ffffffff
ss: sel=00af  base=10000000  limit=0008ffff

Call frame traceback EIPs:
  0x0000eb28
  0x00009cfd
  0x00002ab1
  0x00014f36

- Raw text -