[Fedora-xen] problem creating my 1st VM

[Dustin Henning]

It has been a while since I have used a paravirtualized vm, so my responses
will be vague, but perhaps helpful.
Regarding your original install, both previous responses made good points.
However, I thought some additional explanation might be helpful:
a)
-The kernel line you put in your config makes your vm boot that kernel (the
one on your local disk), so you are already using a xen kernel to boot that
vm.
-There are ready made xen compatible installs of OSes on disk images
available for download at various places, you should be able to find
instructions on how to get thee images into your vm's virtual drive as well.
You may already know this base on your question, but I wasn't sure (I
learned xen before it came on distros and I haven't read the fedora
documentation to see if it  mentions that or where you are copying the files
from for the vms you create).
-Personally, I prefer to use partitions (or even disks) as virtual disks.
This can be done by using (for example) phy:/dev/hdb or phy:/dev/hda4 or
dev:/mapper/lvmvolgroup/lvmvol (or something, LVM certainly makes the
management of multiple virtual but physical disks more manageable) instead
of file:/xenroot/linux/linux.xdi in the first portion of the disk=
arguments.
b)
-You can use a normal/standard kernel in an HVM vm.  This requires that you
have a machine with hardware virtualization, but it allows you to install
windows, boot with a non-xen livecd, etc.  I think there is an example like
/etc/xen/xmexample.hvm for these situations.  In such a case, you wouldn't
have to fdisk the intended virtual partition because the installer you use
when you initially create the machine (windows, linux, whatever) would take
care of that.
etc)
As mentioned by another user, the virtual machine installation executables
(virsh-install/virt-install?) will create a virtual machine that is more
manageable with fedora tools and uses xen capabilities.  I don't know where
config files for these domains are installed, and I prefer the manual
creation via config files and whatnot so I have more control when the time
comes for major changes.  I believe the installer provided on Fedora can
make paravirtualized and hvm machines, and from the sound of a previous
response, it may take care of copying the filesystem on paravirtualized
machines as well.
I hope this helps or at least doesn't hurt.
Dustin

-----Original Message-----
From: fedora-xen-bounces at redhat.com [mailto:fedora-xen-bounces at redhat.com]
On Behalf Of Guillaume
Sent: Friday, October 26, 2007 06:01
To: fedora-xen at redhat.com
Subject: [Fedora-xen] problem creating my 1st VM

Hi list,
I' trying to create my first vm with Xen, and I experience some problems.
I follow some How to's  and xen docs to build my own config file, but
maybe, there are some errors inside it.
I have the following problem, after i start my guest domain, the
kernel boot & then a kernel panix is displayed :

VFS: Cannot open root device "hda1" or unknown-block(0,0)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on
unknown-block(0,0)

I try to start this Virtual machine from vmware workstation where i
install Xen (Dom0 work perfectly).

My config is make up of these lines :
kernel = "/boot/vmlinuz-2.6.20-2936.fc7xen"
root = "/dev/hda1 ro"
name = "test_Linux"
cdrom = "/dev/cdrom"
memory = "128"
builder = "linux"
name = "linux"
disk = [ "file:/xenroot/linux/linux.xdi,hda1,w" ]

Additionnals questions :
a) Does i must use a modified Xen linux kernel, or, can I use a
"normal/standard" kernel to boot up my VM?
b) Is it possible to start a fresh install of Fedora directly from dvd
in a guest domain (I mean without creating & mounting disk image/VM
partition and copying root file system in it? If yes, how ?

Thanks for your replyes.

-- 
Guillaume

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