Message-Id: <199808042352.AAA15999@sable.ox.ac.uk>
Comments: Authenticated sender is <mert0407 AT sable DOT ox DOT ac DOT uk>
From: George Foot <george DOT foot AT merton DOT oxford DOT ac DOT uk>
To: Nate Eldredge <nate AT cartsys DOT com>
Date: Wed, 5 Aug 1998 00:51:42 +0000
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Subject: Re: help! SIGILL?!?
Reply-to: george DOT foot AT merton DOT oxford DOT ac DOT uk
CC: djgpp AT delorie DOT com
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On  4 Aug 98 at 10:37, Nate Eldredge wrote:

> Cephaler wrote:
> > Shutting down Allegro
> > Exiting due to signal SIGILL              <------------ Hmmmmmmmm
> > Invalid Opcode at eip=00092b08
> > eax=00000000 ebx=000900af ecx=000000a0 edx=00000000 esi=00000020
> > edi=000190a0
> > ebp=0008d898 esp=0008d886 program=C:\NICK\DJGPP\GAME\TEST.EXE
> > cs: sel=00a7  base=82739000  limit=0019ffff
> > ds: sel=00af  base=82739000  limit=0019ffff
> > es: sel=00cf  invalid
> > fs: sel=00bf  base=00000000  limit=ffffffff
> > gs: sel=00bf  base=00000000  limit=ffffffff
> > ss: sel=00af  base=82739000  limit=0019ffff
> > 
> > Call frame traceback EIPs:
> >   0x00092b08
> > 
> > I've never gotten that before...did I screw something up in my bios? Even
> > after restarting the problem is still there. Help would be greatly
> > appreciated
> 
> It means what it says-- an invalid opcode was executed (aka ILLegal
> instruction).  First, build the debugging version of Allegro as its docs
> describe.  Rebuild your program with it, run it again, and symify the
> traceback.  

I don't think that will help.  The faulty function seems to 
have set up a call frame; the only possibility I can see is that *EBP 
is zero, which would cause the call frame traceback generator to give 
up immediately after printing EIP.  I don't think a debugging version 
of Allegro will solve that problem.

It's odd that EIP is in the stack.  I can only think that the stack
was garbled and a function tried to return.

-- 
george DOT foot AT merton DOT oxford DOT ac DOT uk