Message-Id:	<m0ykBdV-000S3qC@inti.gov.ar>
Comments:	Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From:	"Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization:	INTI
To:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>, djgpp-workers AT delorie DOT com,
	Morten Welinder <terra AT diku DOT dk>
Date:	Thu, 11 Jun 1998 14:55:06 +0000
MIME-Version:	1.0
Subject:	Re: __dpmi_yield considered harmful (sometimes)
References:	<m0yjTy8-000S4CC AT inti DOT gov DOT ar>
In-reply-to:	<Pine.SUN.3.91.980611201454.26077B-100000@is>

Eli Zaretskii <eliz AT is DOT elta DOT co DOT il> wrote:
> On Tue, 9 Jun 1998, Salvador Eduardo Tropea (SET) wrote:
> 
> > Machine without problems (clean installation): vmm32.vxd 697318 bytes 
> > 1998-06-04, 12:02
> > Machine with more software installed: vmm32.vxd 710034 1998-05-19 12:21
> 
> Yes, I also see widely different VxDs.  Probably, optional packages come 
> with their private versions of vmm32.vxd.  One particularly nasty fella 
> I'd suspect is MSIE v4 (did you maybe installed one on the problematic 
> machine?).

Nope. But I think it could be Office or DirectX, I'll try to see if I can find 
a vmm32.vxd in one of these packages.
 
> > But wait ... that isn't even the original!!! in the .cabs the file is 411132 
> > bytes long.
> 
> That's the compressed size, I'd guess.

No, that's the size after extracting the file from the cabinet file! I taked a 
look to the file using abinary editor and isn't compressed. Is very different 
to the one installed in both systems. It includes a lot of debug messages 
to show register dumps and similar things.

Now I taked a look to a third system, it have:

vmm32.vxd 710114 bytes, time 12:22

and it pass the test so looking at the time of creation of the file my 
conclution is:

In the cabinet files the vmm32.vxd have time 11:11 so that's the real vmm32 for 
W95 v4.00.1111 it have 411Kb.
The others are:
697318 time 12:02 => from v4.00.1202
710034 time 12:21 => from v4.00.1221 *
710114 time 12:22 => from v4.00.1222

(*) fails

So looks like some applications are distributing an updated version of 
vmm32.vxd. After all that seems to be part of the kernel, so they distribute 
upgrades of the OS!!

I'll try to use the 1222 in the machine with 1221 and see if it fixes the 
problem.

> > Looks that the problem could be there, but is hard to know how or why the files 
> > are so different. 
> 
> It actuallu turns out that not only function 1680h, but ALL functions of 
> Int 2Fh wedge the DOS box when invoked from nested DPMI clients, if they 
> are called via INT 2Fh instruction.  __dpmi_int works okay.
> 
> I searched the entire libc.a, but fortunately only __dpmi_yield calls
> Int 2Fh.
> 
> It *is* something to avoid, though.  For example, Emacs called another 
> function of 2Fh and it hung for me on that machine while building (where 
> it is run from Make).
> 
> Seems like the Int 2Fh handler on Windows 95 is badly broken.

Or perhaps was broken from 12xx(>1202) to 1221 and that's why only few people 
experiment problems.

SET
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Visit my home page: http://set-soft.home.ml.org/
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Salvador Eduardo Tropea (SET). (Electronics Engineer)
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