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Date: Wed, 30 Jun 2004 12:36:47 -0500
From: Brian Ford <ford AT vss DOT fsi DOT com>
Reply-To: cygwin AT cygwin DOT com
To: cygwin AT cygwin DOT com
Subject: Re: Cygwin Memory Allocation and heap_chunk_in_mb
In-Reply-To: <Pine.CYG.4.58.0406301223270.4988@fordpc.vss.fsi.com>
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On Wed, 30 Jun 2004, Brian Ford wrote:

> On Wed, 30 Jun 2004, Corinna Vinschen wrote:
>
> > The virtual memory available to a process is 2GB under NT.  I see two
> > possible workarounds:
> >
> > - There's a way to start NT with a "/3gb" switch from boot.ini which
> >   allows to get 3GB of virtual memory per process.  Dunno if that's
> >   available on XP, perhaps the switch is only supported in server
> >   versions of NT.
>
> It is available on XP, but I think it is unsupported on non-server
> platforms.  It's availability is supposed to be for developer testing
> only, or some such nonsense.

Here is the complete story.  From:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/4gt_ram_tuning.asp

    * Windows Server 2003 family
    * Windows XP Professional Edition
    * Windows 2000 Datacenter Server
    * Windows 2000 Advanced Server
    * Windows NT 4.0 Enterprise Edition

and from:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/memory/base/4gt_ram_tuning.asp

This parameter is fully functional on Microsoft Windows NT Server 4.0,
Enterprise Edition with Service Pack 3, Microsoft Windows 2000 Advanced
Server, Microsoft Windows 2000 Datacenter Server, Windows XP, and Windows
Server 2003.

On other versions of Windows NT and Windows 2000, this parameter restricts
the kernel to addresses above the 3 GB boundary. However, user-mode
applications cannot access more than 2 GB of address space.

-- 
Brian Ford
Senior Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained pilot...

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