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RE: [Xen-users] Re: [Xen-devel] Re: need to compile 32bit on x86_64 cpu

To: "Anand Gupta" <xen.mails@xxxxxxxxx>, "Jerone Young" <jyoung5@xxxxxxxxxx>
Subject: RE: [Xen-users] Re: [Xen-devel] Re: need to compile 32bit on x86_64 cpu
From: "Petersson, Mats" <Mats.Petersson@xxxxxxx>
Date: Thu, 22 Jun 2006 23:34:21 +0200
Cc: Harry Butterworth <harry@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Xen Users <Xen-users@xxxxxxxxxxxxxxxxxxx>, Andi Kleen <ak@xxxxxxx>
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Thread-topic: [Xen-users] Re: [Xen-devel] Re: need to compile 32bit on x86_64 cpu
No, you can only run the same-bitness for Xenified guests. Xen 3.x supports unmodified guests at any level of bitness (up to whatever Xen itself is, you obviously can't run a 64-bit unmodified guest on top of a 32-bit Xen).
 
But for Xenified guests, the Xen-build and the Guest-OS must be the same - this is because it's actually quite complicated to translate  the different page-table levels and map the memory such that the guest can access it, etc [not exactly rocket science, of course, but it does make life more difficult for the hypervisor].
 
It has been discussed to make a shim-layer that translates the Xen-calling interface.
 
Is there any particular reason you feel that you must run a 32-bit guest-OS. Almost all applications will work just fine in a 64-bit guest. Of course, there are some exceptions... If so, then you do need to move to 32-bit host-OS as well as guest-OS, yes.
 
--
Mats


From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Anand Gupta
Sent: 22 June 2006 22:25
To: Jerone Young
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx; Harry Butterworth; Xen Users; Andi Kleen
Subject: [Xen-users] Re: [Xen-devel] Re: need to compile 32bit on x86_64 cpu

On 6/23/06, Jerone Young <jyoung5@xxxxxxxxxx> wrote:
If you are using paravirutal Xen (which I believe you are). You "cannot"
use a 32-bit Xen domU kernel with it. You have you use 64-bit Xen domU
kernel with it. I can tell by the path you are using 64bit Xen
"/home/xen/xen-3.0.2-2/dist/install/usr/lib64/python/xen/xend/XendDomainInfo.py". Best to stick with 32-bit Xen if you want to run 32bit domUs.

So i would need to compile and install 32bit version of xen on the dom0 now ? Shouldn't the 64bit allow me to run 32bit domU's as well as 64bit domU's ? (atleast thats what i thought it would allow)

Thanks.

--
regards,

Anand Gupta
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