Re: [Qemu-devel] QEMU patch to allow VM introspection via libvmi

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, Oct 23, 2015 at 08:35:15AM +0200, Markus Armbruster wrote:
> Eduardo Habkost <ehabkost@redhat.com> writes:
> 
> > On Wed, Oct 21, 2015 at 12:54:23PM +0200, Markus Armbruster wrote:
> >> Valerio Aimale <valerio@aimale.com> writes:
> > [...]
> >> > There's also a similar patch, floating around the internet, the uses
> >> > shared memory, instead of sockets, as inter-process communication
> >> > between libvmi and QEMU. I've never used that.
> >> 
> >> By the time you built a working IPC mechanism on top of shared memory,
> >> you're often no better off than with AF_LOCAL sockets.
> >> 
> >> Crazy idea: can we allocate guest memory in a way that support sharing
> >> it with another process?  Eduardo, can -mem-path do such wild things?
> >
> > It can't today, but just because it creates a temporary file inside
> > mem-path and unlinks it immediately after opening a file descriptor. We
> > could make memory-backend-file also accept a full filename as argument,
> > or add a mechanism to let QEMU send the open file descriptor to a QMP
> > client.
> 
> Valerio, would an command line option to share guest memory suffice, or
> does it have to be a monitor command?  If the latter, why?

IIUC, libvmi wants to be able to connect to arbitrary pre-existing
running KVM instances on the host. As such I think it cannot assume
anything about the way they have been started, so requiring they
be booted with a special command line arg looks impractical for this
scenario.

Regards,
Daniel
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