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Subject: Re: Multiple installations and 3PPs
From: Adrian Cox <adrian AT humboldt DOT co DOT uk>
To: cygwin AT cygwin DOT com
In-Reply-To: <20050114171548.GB6227@trixie.casa.cgf.cx>
References: <1105721403 DOT 28030 DOT 53 DOT camel AT localhost> <20050114171548 DOT GB6227 AT trixie DOT casa DOT cgf DOT cx>
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Date: Fri, 14 Jan 2005 18:07:52 +0000
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On Fri, 2005-01-14 at 12:15 -0500, Christopher Faylor wrote:
> On Fri, Jan 14, 2005 at 04:50:03PM +0000, Adrian Cox wrote:
> >Multiple installations of Cygwin clash, both over the registry name
> >used for the mount table and the name of the shared memory region.
> >This makes it difficult to have several versions for testing purposes,
> >and causes problems with software from 3PPs.
> 
> I don't know what "3PPs" (third party providers?) might be but there is
> only supposed to be one version of cygwin1.dll in use on your computer
> at a time.  The DLL even issues a rather verbose error when it detects
> two versions running.

Sorry, just trying to speak the local language:
http://cygwin.com/acronyms/#3PP

I don't understand why it is a goal to have only one version of
cygwin1.dll in use at a single time. I'd like to create separate Cygwin
universes, with no communication between them except via IP networking.

> >Has anybody considered using PSAPI to find the full path to
> >cygwin1.dll, and using a hash of this path as the name of the shared
> >memory region and of the registry key?
> 
> This is rather like asking "Has anyone found a way to put sound
> deadening foam over the little thing that chimes when you're not wearing
> your seatbelt?"  The warnings are there for a reason, not because
> we couldn't figure out how to name the shared memory region to avoid
> clashes.  The problem isn't as simple as trying to avoid shared memory
> clashes.

So what are the other problems? Is there any other way the processes
could become aware of each other's existence, except for making native
Win32 calls?

> [...]
> >(I couldn't find anything with Google, but cygwin-developers isn't
> >indexed).
> 
> That's because cygwin-developers is a private mailing list.

Which is why people like me have to ask so many questions.

-- 
Adrian Cox <adrian AT humboldt DOT co DOT uk>


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