Xen 4.1 kernel error on the IBM x3650 M4

Asked by Richard Gourlay on 2013-01-08

Installed Ubuntu 12.04 LTS Server on the hardware -
Install goes OK as does installing Xen kernel but on reboot get the error
(Not enough memory to relocate the dom0 kernel image).

Will send logs etc. as requested.

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Jeff Lane (bladernr) said : #1

How much memory does your system have? And have you filed a bug against Xen yet? You'll need to. I have a feeling this a simple config problem.

Can you try rebooting and when you get to the grub screen, add this parameter to the grub line for booting the Xen kernel:

dom0_mem=256MB

dom0 is a VM just like any other VMs on a Xen machine, it just happens to be a "special" vm with direct hooks to the hypervisor and underlying hardware.

Do you have any other VMs that are trying to start automatically as well?

Also, what architecture are you running? 64 or 32bit?

Richard Gourlay (rgourlay) said : #2

Jeff,

Thanks, I tried setting dom0_mem to 256MB - I had set to 512MB previously with no success. Also setting Min and Max to 512mmb.

I have posted question on xen-user mailing list.

We have 64Gb of AM and 3TB of RAID 5 disks on each machine.

Ubuntu Server x64 base with Xen 4.1 kernel installed via apt-get xen-hypervisor-amd64

grub2 changed for loading kernel to set dom0_mem to 512MB

no VMs installed yet as dom0 not coming up.

H/W specs are:
IBM x3650 M4
Xeon 8C E5-2650 2.0GHz
64GB RAM
6 x 600Gb in Raid 5

Jeff Lane (bladernr) said : #3

Interesting here: https://launchpad.net/ubuntu/+source/xen/4.1.2-2ubuntu2

The package description for xen-hypervisor-4.1-amd64:
 "The hypervisor is the "core" for XEN itself. It gets booted by the boot
 loader and controls cpu and memory, sharing them between your
 administrative domain (Domain 0) and the virtual guest systems.
 .
 In order to boot a XEN system along with this package you also need a
 kernel specifically crafted to work as the Domain 0, mediating hardware
 access for XEN itself."

That said, AFAIK, the stock Ubuntu kernel is supposed to work with Xen as Dom0 automatically. I did come across a Ubuntu Forums post about the same issue and it involved compiling a custom kernel for dom0 but that doesn't seem right.

First, I'd suggest filing a two bugs:
# ubuntu-bug linux
# ubuntu-bug xen-hypervisor-4.1-amd64

and add as much info as you can.

Second, see the FAQ I'm about to attach regarding actual technical support and community based technical support.

Finally, if you are IRC inclined, there on Freenode, there's a channel called #xen that is where the Xen.org folk hang out and there should be someone there who could probably give better help than I can. Truth be told, it's been about 4 years now since I last REALLY dove into Xen like this, and back then it was on the orginal x3650s. Heh, I had a stack of 8 of them running Xen 3.1 but that's been forever and a day, so while I DO know Xen, I'm not as current on it as I used to be.

Hope some of this helps...

Jeff Lane (bladernr) said : #4

Jeff Lane suggests this article as an answer to your question:
FAQ #1945: “Where can I get help or technical support?”.

Can you help with this problem?

Provide an answer of your own, or ask Richard Gourlay for more information if necessary.

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