From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oren Laadan Subject: Re: kernel based checkpoint/restart: about X windows application checkpoint and restart support. Date: Wed, 28 Oct 2009 12:18:17 -0400 Message-ID: <4AE86EC9.7040605@librato.com> References: <20091028084717.GO31446@count0.beaverton.ibm.com> <4AE85D13.9030108@librato.com> <20091028161219.GQ31446@count0.beaverton.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20091028161219.GQ31446-52DBMbEzqgQ/wnmkkaCWp/UQ3DHhIser@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Matt Helsley Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Will Huang List-Id: containers.vger.kernel.org Matt Helsley wrote: > On Wed, Oct 28, 2009 at 11:02:43AM -0400, Oren Laadan wrote: >> >> Matt Helsley wrote: >>> On Wed, Oct 28, 2009 at 10:51:32AM +0800, Will Huang wrote: >>>> Dear All, >>>> >>>> Did the Kernel based checkpoint/restart patch support X windows >>>> application such as firefox? >>> No, and I think it may be a long time before that happens. >> In short: not yet, but we're getting closer. >> > > (lots of good background) > >> Now back to your question: X applications cannot be checkpointed >> standalone (unless, of course, X windows is modified for that). >> Instead, one must checkpoint the entire user session, including >> the X server itself. >> >> The main problem is that the X server is "talking" to the bare >> hardware, and the task of recording the specific hardware state >> and restoring it later is daunting, and becomes impossible if the >> session is to be restarted on different hardware. >> >> The solution is to not run the regular X server. Instead, start >> a virtual X server, such as VNC, and run the user session in it. >> The main difference is that VNC server does not directly use any >> hardware resources, so it is not tied to specific hardware state. >> From the user's point of view - this setup is transparent with >> suitable use of a VNC client. > > VNC is all well and good but it's hardly the norm for local > desktops to run under an X server with a VNC display. That said, > VNC support is much closer than any of my hare-brained ideas so.. There is a lot of work on server/client split of the X server (of which VNC is one), and also work on embedding one display manager within another (e.g. nested X, and also similar ideas done with embedding a VM window in the desktop as a regular window etc). So eventually, I believe, embedding a (virtualized) X server in an outside X server and running the entire desktop in a container will eventually be possible in a manner transparent to the user. And this is much more likely than checkpoint the standard X server including all it's hardware related state... Changing the norm starts now :) Oren.