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RE: [Xen-devel] X86_64 and 4GB RAM using Flat Memory Model?

To: "John Hannfield" <hal9020@xxxxxxxxx>, "Keir Fraser" <keir@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] X86_64 and 4GB RAM using Flat Memory Model?
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Wed, 2 May 2007 10:07:43 +1000
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Thread-topic: [Xen-devel] X86_64 and 4GB RAM using Flat Memory Model?
Just a suggestion, I had all sorts of problems with funny memory maps
when I was trying to get gPXE (the next version of Etherboot) running on
a particular machine. I can't remember exactly what the problem was but
it was something about overlapping memory regions, or a zero sized
memory region.

Anyway, the way I tracked down that problem was to hack the qemu bios a
bit so that it returned a memory map with the same problems, and then
hack away at the gPXE code until it worked (actually... I think I might
have given the modified qemu bios to the gPXE developers and they got it
working... can't quite remember).

Either way, gPXE with the appropriate debugging turned on might be able
to give you a verbose enough memory map dump to see if you can see what
is wrong. And if you can modify the memory map in the qemu bios to
duplicate that error, it gives you a nice sandbox to test your grub
fixes in!


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