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Date: Thu, 11 Oct 2001 16:05:03 -0400
From: Charles Wilson <cwilson AT ece DOT gatech DOT edu>
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To: Peter Buckley <peter DOT buckley AT cportcorp DOT com>
CC: cygwin AT cygwin DOT com
Subject: Re: Multiple cygwin installs: I have to do it, but how?
References: <3BC5B226 DOT 104 AT ece DOT gatech DOT edu> <3BC5C7B1 DOT BF4ABFB7 AT cportcorp DOT com>
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forwarded to the list on behalf of Bob Cunningham.  disclaimer: the 
following represents Bob's views and not my own.
--Chuck

Thanks Peter.  I'm monitoring the list from the Web always up-to-date
archives at: http://sources.redhat.com/ml/cygwin/2001-10/

Let's forget new-vs-old issues for now:  There's still the generic
question:  **Should** multiple Cygwin installs be supported/allowed?  In
*any* way, shape or form?

Remember, multiple instances are possible for the majority of 
applications under any/all operation systems:  Simply install additional 
copies in separate directories.  We all do this all the time.

This doesn't work for Cygwin for at least two reasons (and probably 
several more, as yet unidentified):
1. The cygwin DLL uses a shared/common memory area.
2. Mount points are kept in the Registry.

I'd like to see both of the above made optional in Cygwin, or 
(preferably) eliminated completely.  Otherwise, Cygwin will be used by 
PC and Windows vendors to make you buy more PCs and more Windows 
licenses:  "Need an additional Cygwin environment?  Get another PC."  ;^)

In essence, the above design/implementation decisions serve to "lock"
Cygwin to a single instance on a single system.  Period.  On my systems,
not even Operating Systems have that right!  (I use Win4Lin whenever I 
can, and Cygwin when I can't.)  I suppose I *could* use VmWare to 
configure multiple NT environments, just so each could have its own 
Cygwin environment.  Silly, I know, but that's what Cygwin presently 
dictates!

It now seems there is no quick or direct solution to my problem:  Only a
Cygwin redesign can allow a generic solution.  The alternative (getting
vendors to all act the same) will be like herding cats, and I suspect 
the results will be just as useful.  For this reason, I'm going to 
recommend to all such vendors that they avoid using Cygwin (or start 
shipping VmWare or a PC with their Cygwin-based products).  After all, 
ANY non-Cygwin CLI tool implementation will still be useful within my 
personal Cygwin environment. Only a "Cygwin native" port of such tools 
screws things up.

So, it seems the Cygwin developer community has a decision to make.  I 
see three distinct paths:

1. Tell vendors NOT to distribute Cygwin with their products. 
Furthermore, any products that are Cygwin dependent should follow a 
stringent set of functional and packaging guidelines.  Such guidelines 
would certainly need some sort of verification/validation mechanism.

2. Eliminate any and all restrictions that make Cygwin unable to coexist
with multiple instances of itself.  Heck, there's even a full user-mode
port of the Linux kernel that can run multiple instances of itself under
Linux.  Why not Cygwin under NT?

3. The status quo:  "Each Cywgin environment needs its own OS instance."
At the very least, vendors considering Cygwin should know this 
limitations exists, and what its significant negative impact is for 
users of their tools who are already Cygwin users.

Does that just about cover the issue?

Regards,
-BobC


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