Virtio Drivers on Dragonfly
check+la6ebi00rs8kogo6 at fromme.com
Tue Oct 12 05:21:08 PDT 2010
Michael Neumann wrote:
> Another great application of vkernels could be for laptops. Imagine your
> laptop runs on DragonFly, and your host kernel is running a X11 display
> server, while all your X11 clients run inside the vkernel. This enables
> you to checkpoint the vkernel, shut down the laptop, and to later
> restore where you left off (assuming X11 doesn't keep state on the
That won't work, because various client data is stored
inside the X server (resources, properties, bitmaps, ...).
Usually an X client will terminate immediately when its
connection to the X server is lost. Also, the X server
will drop all data related to an X client when it loses
the connection to that client.
In order to make the scenario work that you describe, you
would also have to checkpoint the X server at the same
time (which would be difficult because of dependencies on
hardware and drivers), and freeze the connections between
X server and X clients somehow so they're not lost.
Alternatively you could run the X server within the same
vkernel, and find a way to pass graphics hardware access
to the vkernel (not trivial either, because you will have
to restore the graphics hardware state correctly upon thaw).
But I guess this would have serious performance problems.
A third way to do what you want would be to use Xvnc inside
the vkernel. This would be easy to do, and might even be
fast enough. The X clients connect to the Xvnc server
inside the vkernel, so no connections are lost upon check-
point. Upon thaw, you simply re-connect to the Xvnc server
with your VNC client (e.g. tightvnc) running under the host
kernel's X server. I think this should be feasible.
Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M.
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