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Re: [Xen-devel] [PATCH] Elf loader fixes

To: Jan Beulich <JBeulich@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] Elf loader fixes
From: Gerd Hoffmann <kraxel@xxxxxxx>
Date: Wed, 22 Feb 2006 14:33:51 +0100
Cc: Xen devel list <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Jan Beulich wrote:
> I'm afraid this won't work for 64-bits, because of the way the vsyscall page 
> gets set up there. If you dump the program
> headers you'll see that the respective segment is at an address close to the 
> top of the address space, which would make
> the image appear to need nearly 2 Gb of memory (making the load fail if 
> there's less than that available to the
> domain).

Yep, will not work work as-is, the domain builder needs more fixes for that.

> Also, I'm unclear why you need to make persistent the physical address 
> information for the dom0 case, and hence why the
> bug compatibility hack is needed there.

Well, the libxc loader needs it to be able to load both old kernels and
kernels with correct physical addresses in the phdr.

The dom0 loader doesn't really need it, at least on x32, right now it
doesn't look at the physical addresses anyway.  Instead it depends on
the VIRT_BASE hack to get it right.  It's sort of documentation only ;)

For x64 it will certainly be needed to get the memory size calculations
right (use physical not virtual addresses) and fix the issue you've
outlined above that way.



Gerd 'just married' Hoffmann <kraxel@xxxxxxx>
I'm the hacker formerly known as Gerd Knorr.

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