[Xen-users] Re: Migrating from -xen guest kernel to unmodified guest kernel

[Tom Haddon <tom@xxxxxxxxxxxxxxxxx>]

On Thu, 2008-07-10 at 22:41 +0100, Tom Haddon wrote:
> Hi Folks,
> 
> I'm trying to switch a guest from using a -xen guest kernel to using an
> unmodified guest kernel. 

> As I understand it, there are a few things that I'd need to do to be
> able to do this.
> 
> 1) Install the kernel on the guest itself, and configure grub on the
> guest itself to boot that kernel
> 2) Because I need to install grub, I need to switch from using
> file-based partitions (/dev/hda1) to file-based disks (/dev/hda
> with /dev/hda1 and /dev/hda2 as a partition within that).
> 
> I think that what I may need to do is build the whole /dev/hda disk
> image from scratch, and then mount it as a loopback device, and create
> the partition layout I want and format the partitions as ext3 and swap
> respectively. Then I should also mount the current /dev/hda1 image as
> loopback devices, and then copy everything into the first partition. 
> 
> Then I should be able to change my disk config to:
> 
> disk = [ 'tap:aio:/srv/xen/domains/dapper/new_disk.img,hda,w' ]
> 
> I'd then boot into it and install grub, shut it down, change the config
> to use hvmloader, and then boot again. Does this sound sane?

I was successfully able to do this, and can now boot into the new guest
with the unmodified kernel. However, networking doesn't work. (I figured
out how to connect via vnc through an ssh tunnel). In other words, the
network setup works fine with the -xen kernel, but not with the
unmodified kernel. Anyone have any ideas why that might be?

> 
> Part of the reason I need to avoid just building a new unmodified kernel
> guest from scratch is that I can't seem to get console access to the xen
> guest when it's using hvm (I think this isn't supported from what I can
> see), and I don't have firewall access to be able to get to the server
> on a vnc port. I also can't get xen to work on my current laptop (kernel
> panic), so I'm stuck with trying to do things directly on the server.

Since I have the ssh tunnel and a vnc connection, I thought I'd just try
installing from scratch. However, I'm having some problems with that
too. If I use disk type "tap:aio:" (which is what I've been using in my
guests to date) the guest just dies immediately with no useful error
message. If I change both the hda and cdrom to "file:" the guest goes
into immediate "pause" mode. If I force "unpause" I can carry on with
the install but it fails trying to setup disks as part of the install
with the output:

Error: Device 768 (vbd) could not be connected.
losetup /dev/loop6 /srv/xen/domains/dapper/hvmfulldisk.img failed

Any ideas?

Cheers, Tom

> 
> Many thanks for any help.
> 
> Tom

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