[one-users] Non clonable readonly shared OS image?

Fabian Wenk fabian at wenks.ch
Thu Sep 8 12:07:08 PDT 2011

Hello Ismael

On 08.09.2011 20:03, Ismael Farfán wrote:
> 2011/9/8 Fabian Wenk:

>>>  Mainly I was wondering why with readonly=yes the VM doesn't boot at
>>>  all, it fails before even calling kvm and I can't figure out why.
>>  I guess this is not supported from ONE if an OS image (not CD image) is set
>>  to read only, and it will abort at an early stage. Did you see anything in
>>  the log/one/<VID>.log file?
> I attached the log (almost the same as in the firs mail), whatever ONE does
> different while setting the image as readonly makes libvirt trow this error that
> I haven't been able to fix jet:
> failed to retrieve chardev info in qemu with 'info chardev'

Google [42] does find many reports with this particular message, 
maybe you can find a hint there.


According to your attached log file it fails when ONE tries to 
start kvm, probably because kvm does not support booting from a hd 
image which is set to read only. I guess all this parameters are 
delivered through libvirt to kvm. So kvm is able to honor such 
parameters as read only disk from the "hardware" point of view, so 
the OS in the VM does not have any possibility to write to the disk.

I have seen similar errors with my first steps with ONE, which 
most often where of no real help. But sometimes I found a hint in 
the libvirt log file. I do not remember if I tried it with a hd 
image which was set to read only.


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