[Libvir] virDomainConfigureDevice?

[Richard W.M. Jones]

Hugh Brock wrote:
> I'm looking at ways to replicate xm block-configure at the libvirt 
> level. xm block-configure is useful in that it allows you to change the 
> back device for an HVM guest while the guest is still running; this 
> permits you for example to change the CDROM without shutting down your 
> guest or poking around in xenstore. Thus we can have an "eject" button 
> on cdrom devices in virt-manager (or "eject" and "load" buttons, I 
> guess), which we really need.
> 
> The issue of course is that xm block-configure is specifically intended 
> for block devices and takes arguments for the back device and the front 
> device (among others). We would naturally prefer to accept a block of 
> XML just as virDomainAttachDevice does and then parse it, determine if 
> the device in question is of a type we can actually edit, determine if 
> the new backdev is appropriate, and so on.

Definitely this will be useful for USB ...

I think the question is: Should we have another entry point 
(virDomainConfigureDevice), or should we just modify 
virDomainAttachDevice so that if it sees XML for a device which is 
already attached it just modifies the device?

> None of this seems terribly hard, but before I go implement it, are 
> there obvious pitfalls I'm not thinking? And given that 
> virDomainAttachDevice is not implemented for qemud in libvirt (is it?), 
> how do we handle the non-xen case?

It seems like it isn't implemented for qemud.  Changing the CD-ROM is 
possible through the qemu monitor, so it should be.

Rich.

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