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Re: [Xen-devel] Xen 3.0 x86 + PAE with > 16 GB RAM?

To: Derrik Pates <demon@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Xen 3.0 x86 + PAE with > 16 GB RAM?
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 9 Jan 2006 10:30:12 +0000
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On 6 Jan 2006, at 22:21, Derrik Pates wrote:

Can this safely be increased? From my reading of the code, it appears
that it is set as it is because each gigabyte of installed RAM requires
a megabyte of RAM to be set aside for mapping tables and such. If I just
increase the value of MACHPHYS_MBYTES to 32 (for example), should Xen
boot and work happily, just consuming more RAM for its mapping tables?

Please Cc: me with your reply, as I'm not subscribed to this list currently.

The memory layout of Xen is hardcoded in asm-x86/config.h, and also in public/arch-x86_32.h. If the addresses of certain critical structures are modified appropriately then things should work fine. Of course Linux will end up with less kernel virtual address space and hence less lowmem.

 -- Keir

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