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Date: Tue, 11 Dec 2001 20:13:43 +0200
From: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>
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To: sandmann AT clio DOT rice DOT edu
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In-reply-to: <10112110836.AA20180@clio.rice.edu> (sandmann@clio.rice.edu)
Subject: Re: Alternate exit code to set psp
References:  <10112110836 DOT AA20180 AT clio DOT rice DOT edu>
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> From: sandmann AT clio DOT rice DOT edu (Charles Sandmann)
> Date: Tue, 11 Dec 2001 02:36:40 -0600 (CST)
> > > 
> > >   asm volatile("movb $0x51, %%ah
> > >                 int  $0x21
> > >                 movb $0x50, %%ah
> > >                 int  $0x21
> > > 
> > > (so we don't pass the psp any more, we do a getpsp call to decide
> > > what to set it to).
> > 
> > Won't this do harm if the PSP you get is zeroed (by the same NTVDM bug we 
> > are trying to fix)?
> 
> The PSP returned by DOSX (DPMI) is still correct, so when we do the set
> it cleans up the internal bogosity in NTVDM.  
> 
> It appears to work (at least most of the time ...).  My patched gcc 2.8.1
> driver which uses this code would crash each 1-3 compiles without it, but
> only crashed once with it.  I was going to see if that crash was 
> reproducible.  The old code might be more reliable, but I don't see
> how to have a child program know if it's run from a go32-v2.

Well, I'm paranoiac nonetheless, primarily because this code wasn't
tested except now, while the old code was tested by several users on
several different systems.

So I'd prefer a solution which just fixes the old code, so that when
it runs under go32-v2, it doesn't call PM Int 21h at all.