Xen devel - Jul 2005 - using domain0 file as root disk for domU

I know I''ve seen this before but can''t find it...

Can someone provide a pointer to (or if simple,
just a quick reply) how to use a domain0 file as
a root disk for a domU?

I am able to mount the file as a loopback device:

mount -o loop,offset=512 -t ext2 /var/xen/sda /mnt

But how do I specify it in xmdefconfig?  I tried:

disk = [ ''phy:/mnt,hda1,w'' ]

disk = [ ''/mnt,hda1,w'' ]

Thanks,
Dan

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On Sat, Jul 16, 2005 at 06:11:08AM -0700, Magenheimer, Dan (HP Labs Fort
Collins) wrote:
> disk = [ ''phy:/mnt,hda1,w'' ]
disk = [ ''file:/my_file,<that is imho the device the domU
"sees"?>,w'']

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Magenheimer, Dan (HP Labs Fort Collins) wrote:
>I know I''ve seen this before but can''t find it...
>
>Can someone provide a pointer to (or if simple,
>just a quick reply) how to use a domain0 file as
>a root disk for a domU?
>
>I am able to mount the file as a loopback device:
>
>mount -o loop,offset=512 -t ext2 /var/xen/sda /mnt
>
>But how do I specify it in xmdefconfig?  I tried:
>
>disk = [ ''phy:/mnt,hda1,w'' ]
>
>disk = [ ''/mnt,hda1,w'' ]
>  
>
disk = [ ''file:/var/xen/sda,hda1,w'' ]

Make sure you unmount it in dom0 first! :)

Thanks,
Paul Larson

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Error: Error creating domain: cannot concatenate ''str'' and
''NoneType''
objects 
> >Can someone provide a pointer to (or if simple,
> >just a quick reply) how to use a domain0 file as
> >a root disk for a domU?
> >
> >I am able to mount the file as a loopback device:
> >
> >mount -o loop,offset=512 -t ext2 /var/xen/sda /mnt
> >
> >But how do I specify it in xmdefconfig?  I tried:
> >
> >disk = [ ''phy:/mnt,hda1,w'' ]
> >
> >disk = [ ''/mnt,hda1,w'' ]
> >  
> >
> disk = [ ''file:/var/xen/sda,hda1,w'' ]
> 
> Make sure you unmount it in dom0 first! :)
Hmmm... when I try this, I get:

Error: Error creating domain: cannot concatenate ''str'' and
''NoneType''
objects 

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Dan,

Could you try this:
losetup /dev/loop2 /dev/sda1

then modify domU config:
disk = [ ''file:/dev/loop2, sda1, w'' ]
root = "/dev/sda1 ro"

It can boot. But I meet some problem when file system check, maybe it is
because my dom0 and domU used same file system.

Thanks,
Yongkang You(Kangkang)
>-----Original Message-----
>From: xen-devel-bounces@lists.xensource.com [mailto:xen-devel-
>bounces@lists.xensource.com] On Behalf Of Magenheimer, Dan (HP Labs
>Fort Collins)
>Sent: Monday, July 18, 2005 6:30 AM
>To: Paul Larson
>Cc: xen-devel@lists.xensource.com
>Subject: RE: [Xen-devel] using domain0 file as root disk for domU
>
>Error: Error creating domain: cannot concatenate ''str'' and
''NoneType''
>objects
>
>> >Can someone provide a pointer to (or if simple,
>> >just a quick reply) how to use a domain0 file as
>> >a root disk for a domU?
>> >
>> >I am able to mount the file as a loopback device:
>> >
>> >mount -o loop,offset=512 -t ext2 /var/xen/sda /mnt
>> >
>> >But how do I specify it in xmdefconfig?  I tried:
>> >
>> >disk = [ ''phy:/mnt,hda1,w'' ]
>> >
>> >disk = [ ''/mnt,hda1,w'' ]
>> >
>> >
>> disk = [ ''file:/var/xen/sda,hda1,w'' ]
>>
>> Make sure you unmount it in dom0 first! :)
>
>Hmmm... when I try this, I get:
>
>Error: Error creating domain: cannot concatenate ''str'' and
''NoneType''
>objects
>
>_______________________________________________
>Xen-devel mailing list
>Xen-devel@lists.xensource.com
>http://lists.xensource.com/xen-devel
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* Magenheimer, Dan (HP Labs Fort Collins) <dan.magenheimer@hp.com>
[2005-07-18 09:05]:
> I know I''ve seen this before but can''t find it...
> 
> Can someone provide a pointer to (or if simple,
> just a quick reply) how to use a domain0 file as
> a root disk for a domU?
disk = [''file:/etc/xen/roots/debian_sarge_dom1_512M,sda1,w'']

Xend will automatically loopback mount the file to a loopdevice.

-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@us.ibm.com

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> > >Can someone provide a pointer to (or if simple,
> > >just a quick reply) how to use a domain0 file as
> > >a root disk for a domU?
> > >
> > >I am able to mount the file as a loopback device:
> > >
> > >mount -o loop,offset=512 -t ext2 /var/xen/sda /mnt
> > >
> > >But how do I specify it in xmdefconfig?  I tried:
> > >
> > >disk = [ ''phy:/mnt,hda1,w'' ]
> > >
> > >disk = [ ''/mnt,hda1,w'' ]
> > >  
> > >
> > disk = [ ''file:/var/xen/sda,hda1,w'' ]
> > 
> > Make sure you unmount it in dom0 first! :)
> 
> Hmmm... when I try this, I get:
> 
> Error: Error creating domain: cannot concatenate ''str''
and
> ''NoneType'' objects 
In case anyone else runs into this, the problem was that
/sbin was not in my PATH and losetup is used in a script
without a path.

Dan

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