[libvirt] RFC: Exposing backing chains in <domain> XML

[Eric Blake]

On 03/14/2014 08:34 AM, Daniel P. Berrange wrote:
>>> I don't think we want todo that - there are genuine use cases where
>>> that is a reasonable thing todo. eg you can provide a raw file to a
>>> guest and that guest may genuinely want to format the virtual disk
>>> it received with some other format. We don't want to taint such use
>>> cases.
>>
>> Ewww by formatting you mean turning raw into qcow2??
> 
> Yes, RHEV for example formats block devices as QCow2. I'm not saying
> this is a good idea, but we know of apps which do this and so we
> shouldn't taint this.

RHEV is the host, not the guest - and as long as RHEV tells us <driver
format='qcow2'>, then they keep libvirt in the loop on what the backing
chain should be.

I'm only thinking of tainting where the backing chain as explicitly
stated in XML differs from the backing chain found by actual scans,
_and_ where the actual scans do not probe file types from any file
explicitly marked raw in the XML.  There's a good reason we refuse to
scan any file explicitly marked raw.


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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