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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Thu, 27 May 2004 18:33:20 -0400 (EDT)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: Baurjan Ismagulov <ibr AT ata DOT cs DOT hun DOT edu DOT tr>,
   Michael Hale <michaelh AT cipheroptics DOT com>
cc: cygwin AT cygwin DOT com
Subject: Re: dll version collision
In-Reply-To: <20040527212657.GC2617@ata.cs.hun.edu.tr>
Message-ID: <Pine.GSO.4.58.0405271823590.25579@slinky.cs.nyu.edu>
References: <E164AD5F-B01F-11D8-BECE-000A95C4BF56 AT cipheroptics DOT com> <20040527212657 DOT GC2617 AT ata DOT cs DOT hun DOT edu DOT tr>
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On Thu, 27 May 2004, Baurjan Ismagulov wrote:

> Hello, Michael!
>
> On Thu, May 27, 2004 at 04:53:17PM -0400, Michael Hale wrote:
> > Is it possible to recompile a subset of the cygwin binaries to depend
> > on cygwin1.dll renamed to something like build_cygwin1.dll?  How would
> > I go about doing this?

Some comments:

> This is a quite often-discussed topic, but there is not much info in the
> archives. All I could understand is:
>
> * It isn't possible with the current cygwin.

It is possible, but non-trivial.  Take a look at how the Cygwin testsuite
runs.  However, you shouldn't do this unless you know exactly what you're
doing.

> * One needs at least to rename the library and use different registry
>   entries and shared memory areas in different versions; perhaps
>   something else.

That's pretty much it, IIRC.  You can even share the mounts/registry
entries.

> * Max Bowsher has a working version, albeit of an older cygwin. He
>   wanted to patch the latest version himself, but I'm eager to see even
>   the old patch, it would be a great starting point without duplicating
>   the effort. Max, ple-e-ase :) ?

One way to have Cygwin automatically modify the shared memory area name is
to compile it with debugging (by passing the --enable-debugging flag to
configure).  The trick here is that once you have such a cygwin1.dll,
you'll have to spawn the process that uses it via Windows mechanisms,
rather than Cygwin's own fork.  Again, take a look at the testsuite
scripts, in particular the "cygrun.c" file, or just run it from a
shortcut or the cmd console.

> I'm also interested in this kind of setup, but unfortunately, I haven't
> got much time for this. If you are going to work on this, I could also
> contribute some bits.
>
> With kind regards,
> Baurjan.

I repeat: you really should know what you're doing before you attempt
this.  I can't emphasize this enough.  But it *is* possible.

To the OP: why not simply have an internal Cygwin mirror and make sure
everyone has the same version of Cygwin on their machine?
	Igor
-- 
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