xenU wont boot, cannot open root device

xenU wont boot, cannot open root device

[Maurice Meeden]

Hi,

I am trying to replace uml with xen, but I cant get the unpreviliged Domains
booting..
Ive tested a cuple of filesystems in a file (ext3 or xfs formatted) and Ive also
tried the ttylinux-xen image. But I always get this error:
VFS: Cannot open root device "hda1" or unknown-block(3,1)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(3,1)

The config is the same as in the example:
kernel = "/uml/linux-2.6.9-xenU"
memory = 64
name = "ttylinux"
nics = 1
disk = [ 'file:/uml/ttylinux-xen,hda1,w' ]
root = "/dev/hda1 ro"

Ive also tried sda1 instead of hda1, or hexadecimal.

Ans I also tested different versions, xen 2.0.1 and 2.0-testing, with a stock
Linux kernel, and the prepatched Gentoo-dev-2.6.9 Version. I compiled with and
without 4k stacks, but always the same :-(

Ive no ideas what else I could try, can somebody give me an hint please?

Greetings Maurice




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Re: xenU wont boot, cannot open root device

[Derrik Pates]

Maurice Meeden wrote:
> I am trying to replace uml with xen, but I cant get the unpreviliged Domains
> booting..
> Ive tested a cuple of filesystems in a file (ext3 or xfs formatted) and Ive also
> tried the ttylinux-xen image. But I always get this error:
> VFS: Cannot open root device "hda1" or unknown-block(3,1)
> Please append a correct "root=" boot option
> Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(3,1)

> Ive no ideas what else I could try, can somebody give me an hint please?

Are you using the prebuilt unprivileged-domain kernel image? If so, the 
one in 2.0.1 at least (maybe others, not sure) has devfs support 
enabled. This breaks things. I suggest you rebuild your domU kernel 
_without_ devfs support, and it should work correctly. I had this same 
problem when I began playing with Xen, but after rebuilding the kernel 
as I mentioned, it all worked correctly.

-- 
Derrik Pates
dpates@dsdk12.net


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Re: xenU wont boot, cannot open root device

[Maurice]

> Maurice Meeden wrote:
> > I am trying to replace uml with xen, but I cant get the unpreviliged
> Domains
> > booting..
> > Ive tested a cuple of filesystems in a file (ext3 or xfs formatted) and
> Ive also
> > tried the ttylinux-xen image. But I always get this error:
> > VFS: Cannot open root device "hda1" or unknown-block(3,1)
> > Please append a correct "root=" boot option
> > Kernel panic - not syncing: VFS: Unable to mount root fs on
> unknown-block(3,1)
> 
> > Ive no ideas what else I could try, can somebody give me an hint please?
> 
> Are you using the prebuilt unprivileged-domain kernel image? If so, the 
> one in 2.0.1 at least (maybe others, not sure) has devfs support 
> enabled. This breaks things. I suggest you rebuild your domU kernel 
> _without_ devfs support, and it should work correctly. I had this same 
> problem when I began playing with Xen, but after rebuilding the kernel 
> as I mentioned, it all worked correctly.

Thank you very much, it works now.
Ive thought its enough to add devfs=nomount to the kernel parameters, but
you are right, CONFIG_DEVFS_FS must be unset.

Merry Xmas, Maurice


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