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From: ericblake AT comcast DOT net (Eric Blake)
To: Bob Rossi <bob AT brasko DOT net>, cygwin AT cygwin DOT com
Subject: Re: mismatched dll
Date: Thu, 02 Feb 2006 20:42:34 +0000
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> > No.  There must be only ONE cygwin1.dll on your entire system.  It
> > should be in your cygwin /bin directory.  Period.
> 
> Wow, that seems very inflexible. Is this a design decision?

Yes.  Cygwin DEPENDS on shared memory between processes,
in order to emulate POSIX semantics.  If you have two different
.dlls trying to share the same memory, but with different
ideas of what the semantics of that memory are, you invariably
have problems.  Cygwin prints out the error message you saw
rather than trying to be backwards compatible to all earlier
releases of the .dll in how this shared memory is used, because
it is just easier that way.

> 
> > > Is this the approved way of releasing cygwin with an application?
> > 
> > AFAIK there is no approved way of releasing cygwin together with
> > *anything*, as it is bound to lead to such problems.
> 
> Why would 1 cygwin.dll care about another on the system that has nothing
> to do with it?

Because it DOES have something to do with it.  See also
http://cygwin.com/acronyms/#3PP

> 
> I have N different versions of our product installed on my windows
> machine, and each has a slightly diffferent vresion of qt.dll. This
> isn't a problem at all. What's limiting Cygwin?

Windows .dll design.

> 
> BTW, this worked before I upgraded cygwin. So it is at least possible if
> they are the same version?

Possible?  Yes.  Wise?  No.  You are tempting fate - almost
as surely as you try this, you will forget to upgrade one of
the two copies, and be right back at this issue.  Hence the
official stance of this list is to only ever have a SINGLE
cygwin1.dll on your machine.

--
Eric Blake

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