domU kernel panic with root fs

domU kernel panic with root fs

[Bjoern Sessler]

Hi,

i installed xen 2.0 on my new installed gentoo box. xen0 works great, 
but i can't get domU kernel to mount root fs:

VFS: Cannot open root device "sda5" or unknown-block(8,5)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on 
unknown-block(8,5)

this happens with all root-fs i've tried, ttylinux and my cloned root 
from Xen0. ttylinux lives now on a hdc partition, the cloned root were 
lvm2 devices over kernlraid, which worked fine on my old gentoo with 
xeno-unstable.

fstab on ttylinux also points to sda5, sda5 also exists on Xen0, but 
also hda1 doesn't work. i also saw similar problem with wrong config of 
disk= parameter, but doesn't help me.

config looks like following for these parts:

# disk = [ 'phy:vg1/vm101,hda1,w', 'phy:vg1/vm101-swap,hda2,w', 
'phy:sdb7,hdc1,r!', 'phy:sdc5,hdc2,r!' ]
disk = [ "file:/machines/backup/ttylinux-xen,sda5,w" ]
#disk = [ 'phy:hdc6,hda1,w' ]

#ip = "192.168.1.101"
#netmask = "255.255.255.0"
#gateway = "192.168.1.1"

# Set root device.
root = "/dev/sda5 ro"

i believe i forgot something in the kernel for XenU but i started with 
default-config.

Thanks & Regards,
Björn




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Re: domU kernel panic with root fs

[Dan Cardamore]

Bjoern Sessler <bjoern.sessler <at> web.de> writes:
> 
> Hi,
> 
> i installed xen 2.0 on my new installed gentoo box. xen0 works great, 
> but i can't get domU kernel to mount root fs:
> 
> VFS: Cannot open root device "sda5" or unknown-block(8,5)
> Please append a correct "root=" boot option
> Kernel panic - not syncing: VFS: Unable to mount root fs on 
> unknown-block(8,5)


I'm having the exact same problem, does anyone know of a solution?

>From dom0 I can 'mount -o loop rootfs /mnt/loop' no problems.  It's an ext3
filesystem which my 2.4.27 kernel supports.

Dan



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Re: domU kernel panic with root fs

[Björn Sessler]

Dan Cardamore schrieb:

>> Hi Bjoern,
>> 
>> I'm having the same problem that you posted on xen-devel a week ago
>> regarding the error message "Cannot open root device "sda5" or
>> unknown-block(8,5)".
>> 
>> Did you ever get that solved?
>> 
>> Dan
>> --
>> Dan Cardamore
>> dan@hld.ca

 > I managed to figure out that this is related to devfs.  Whenever I
 > have devfs support compiled in it panics.  This is even if I don't
 > mount devfs (devfs=mount) and don't have "Automatically mount at boot 
 > time" in the kernel config.
 >
 > Anyone know why?  This is a significant nuisance if you're running a
 > gentoo system.

Hi Dan,

ehhm, i remember now there was an issue with devfs in my fist 
installation. did i add gentoo=nodevfs as a boot option to enable gentoo 
to work without devfs? but i thought i added only to xen0, because xen 
1.2 didn't cope with devfs in this version. i will have a look on that 
tomorrow or friday when at home and give it a try.

Regards,
Björn



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