Comments on: Hardware passthrough in LXC (or: running a desktop in a cgroup)

By: John

John — Fri, 27 Aug 2010 12:00:37 +0000

Hi, just to let you know…

I have two X desktops running independently on two virtual terminals (currently one on the host and one in a container).

I have ALSA working in both for multiple users, but only from either the host or the container at any one time. I am working to try and get over that problem.

By: jonnor

jonnor — Mon, 23 Aug 2010 06:50:25 +0000

You will have to create the directory “/srv/lxc/arch/dev” and then possibly a dummy file “/srv/lxc/arch/dev/mem” before you bind mount like that. mknod should not be required.

Also, I realized that access to /dev/mem should only be necessary when using VESA (and possibly some of the prop. drivers). If you’re using a DRI based driver, access to /dev/dri should be enough, though I have not found the time to verify this.

By: John

John — Sun, 22 Aug 2010 13:43:37 +0000

Hi, good to see someone else is interested in doing this. If I accept the “risk” of access to /dev/mem (because all the containers are mine and on my own PC) then it would be good to get this to work.

However, I can’t bind mount /dev/mem into the container. I have tried in the container fstab, like this: “/dev/mem /srv/lxc/arch/dev/mem auto rw,bind 0 0″ but container startup fails because /dev/mem is not a directory.

I tried giving access via cgroups like this: “lxc.cgroup.devices.allow = c 1:1″ but container startup fails.

I tried creating /dev/mem inside the container (as root) “mknod /dev/mem c 1 1″ but this gives “mknod: `/dev/mem’: Operation not permitted”

I wondered if you had any luck getting X in an LXC container and could share some guidance…?

By: jonnor

jonnor — Wed, 18 Aug 2010 12:27:49 +0000

Hey John, nice to see some interest. As you probably known, on a single host, running one Xorg session per tty is trivial. But I’m not sure how much more complicated it gets when you want each in its own container. I would imagine it requires access to the framebuffer device at least, but that might be simple. I can only suggest trying it out, asking questions (on the lxc-users mailing-list perhaps) if you get stuck. And report back once you get it working (or know what it would take)

I’d like to research some more and improve the situation for running desktops in LXC containers, but it’s currently far from the top of my TODO list.

By: john

john — Wed, 18 Aug 2010 10:10:13 +0000

Hello Jon. This is interesting and is something that I am also investigating. If LXC can do this then it’s another nail in the coffin for OpenVZ as far as I am concerned.

Now, would it be possible to give one container tty7 and another tty8 and have two completely different distributions running their own X desktop that can be switched between using CTRL+ALT+F8 and CTRL+ALT+F7

By: Vladimir

Vladimir — Thu, 27 May 2010 07:13:12 +0000

Very interesting, I would like to learn more.
I also try to start Xorg in several LXC, but while it failed