Date: Wed, 29 Jul 1998 11:44:07 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Martin Str|mberg <ams AT ludd DOT luth DOT se>,
        Charles Sandmann <sandmann AT clio DOT rice DOT edu>
cc: DJGPP-WORKERS <djgpp-workers AT delorie DOT com>
Subject: Re: info core dumps
In-Reply-To: <199807281847.UAA20756@father.ludd.luth.se>
Message-ID: <Pine.SUN.3.91.980729114333.8425O-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Precedence: bulk


On Tue, 28 Jul 1998, Martin Str|mberg wrote:

> Ok, here are the results. All configurations except the last work.

Thanks a lot for your efforts.

Charles, can you comment on this?  It seems that EMM386 itself
generates the exception, or somehow contributes to it.  The last two
configurations have the font table in the same place (FFFF:BF32), the
only difference is that in the case which works EMM386 is not loaded.

To recap, this program accesses the active font table at ES:BP using farptr
functions, SRC is the linear address where the table begins, and EAX
is the linear address where it crashes (if it crashes).

> The program was compiled using DJGPP v201.
> 
> es and bp is the seg:off you asked for, font_seg is probably not
> interesting and src and dest is calculated from seg:off respectively
> font_seg: 
> src =  ( ( (unsigned)regs.x.es ) << 4 ) + regs.x.bp;
> dest = ( (unsigned)font_seg ) << 4;
> 
> QEMM, QDPMI, DJGPP v201: works fine:
> es = 0xffff; bp = 0xb4f2; font_seg = 0x2cee; src = 0x10b4e2; dest = 0x2cee0.
> 
> QEMM, QDPMI, DJGPP v202: works fine:
> es = 0xffff; bp = 0xb4f2; font_seg = 0x2cf8; src = 0x10b4e2; dest = 0x2cf80.
> 
> QEMM, CWSDPMI, DJGPP v202: works fine:
> es = 0xffff; bp = 0xb4f2; font_seg = 0x2634; src = 0x10b4e2; dest = 0x26340.
> 
> EMM386, No DISPLAY.SYS, DJGPP v202: works fine:
> es = 0xc000; bp = 0x4ab0; font_seg = 0x2a34; src = 0xc4ab0; dest = 0x2a340.
> 
> No EMM386, DISPLAY.SYS, DJGPP v202: works fine:
> es = 0xffff; bp = 0xbf32; font_seg = 0x5634; src = 0x10bf22; dest = 0x56340.
> 
> 
> EMM386, DISPLAY.SYS, DJGPP v202: crashes:
> es = 0xffff; bp = 0xbf32; font_seg = 0x2e34; src = 0x10bf22; dest = 0x2e340.
> Exiting due to signal SIGSEGV
> Page fault at eip=00001e67, error=0005
> eax=0010c000 ebx=0002e455 ecx=00000006 edx=00000000 esi=0010c001
> edi=0000001b
> ebp=0004dcc0 esp=0004dc58 program=c4.exe
> cs: sel=00e7  base=100a0000  limit=0005ffff
> ds: sel=00ef  base=100a0000  limit=0005ffff
> es: sel=00ef  base=100a0000  limit=0005ffff
> fs: sel=00ff  base=00000000  limit=ffffffff
> gs: sel=00ff  base=00000000  limit=ffffffff
> ss: sel=00ef  base=100a0000  limit=0005ffff
> 
> Call frame traceback EIPs:
>   0x00001e67
>   0x00001e98
>   0x00002cd2
> 
> 
> Silence,
> 
> 							MartinS
>