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[Xen-devel] 16 GB limit on Xen x86-32 PAE?

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] 16 GB limit on Xen x86-32 PAE?
From: "Subrahmanian, Raj" <raj.subrahmanian@xxxxxxxxxx>
Date: Fri, 4 Nov 2005 15:40:27 -0500
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Thread-topic: 16 GB limit on Xen x86-32 PAE?
I was trying to find out what the maximum limit for memory is on x86-32
PAE. 
I discovered that the limit was 16 GB and it was set in
xen/asm-x86/config.h

#define MACHPHYS_MBYTES        16 /* 1 MB needed per 1 GB memory */
#define FRAMETABLE_MBYTES (MACHPHYS_MBYTES * 6)

Is there any reason for this 16 GB limit? Doesn't PAE permit us to
access up to 64 GB?
If we wanted to access 64 GB what else would need to be fixed?
Thanks
Raj

PS. I tried changing MACPHYS_MBYTES to 64 and it didn't seem to break
anything. Of course, I am running on a 4 GB system.

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