Re: [Qemu-devel] Re: [libvirt] Supporting hypervisor specific APIs in libvirt

[Avi Kivity]

On 03/23/2010 08:00 PM, Avi Kivity wrote:
> On 03/23/2010 06:06 PM, Anthony Liguori wrote:
> > > I thought the monitor protocol *was* our API. If not, why not?
> >
> > It is.  But our API is missing key components like guest 
> > enumeration.  So the fundamental topic here is, do we introduce these 
> > missing components to allow people to build directly to our interface 
> > or do we make use of the functionality that libvirt already provides 
> > if they can plumb our API directly to users.
>
> Guest enumeration is another API.
>
> Over the kvm call I suggested a qemu concentrator that would keep 
> track of all running qemus, and would hand out monitor connections to 
> users.  It can do the enumeration (likely using qmp).  Libvirt could 
> talk to that, like it does with other hypervisors.

To elaborate

qemud
  - daemonaizes itself
  - listens on /var/lib/qemud/guests for incoming guest connections
  - listens on /var/lib/qemud/clients for incoming client connections
  - filters access according to uid (SCM_CREDENTIALS)
  - can pass a new monitor to client (SCM_RIGHTS)
  - supports 'list' command to query running guests
  - async messages on guest startup/exit

qemu
  - with -qemud option, connects to qemud (or maybe automatically?)

qemudc
  - command-line client, can access qemu human monitor

--
Do not meddle in the internals of kernels, for they are subtle and quick to 
panic.