[libvirt] XML support for arbitrary command line arguments

[Daniel P. Berrange]

On Tue, Sep 14, 2010 at 11:03:04AM +0530, Harsh Bora wrote:
> As QEMU provides support for accessing such shared directory with the 
> help of 9p server, and therefore need to be passed additional 
> commandline argument while starting, I wanted to test it using XML and 
> libvirt.

> So, if the idea looks good to everyone, we can have something like:
> 
> <shareddir fstype=local path='/folder/to/share' mount_tag='unique_tag' 
> security_model='as_applicable'>

We already have an XML syntax defined for filesystems using 
the <filesystem> element. I've proposed an impl for QEMU using
p9fs before, but we didn't apply it yet. 

  http://www.redhat.com/archives/libvir-list/2010-July/msg00458.html

Unfortunately QEMU does not have monitor commands available for the
filesystem hotplug/unplug, which would make this a far more useful 
feature to users. eg so a user can open up the graphical console,
attach their home directory and access files without having to 
restart the guest.

The other interesting question to me is actually what todo in the guest
with this. I think for this to be useful we really want some kind of
magic in udev to automatically mount the filesystem based on the
mount tag data, and in particular define some kind of rule / semantics
for the mount tag otherwise every OS is going to interpret this 
differently making it a real pain to work with.

Regards,
Daniel
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