[lxc-users] /proc/mtrr permissions inside container keep X from running inside LXC without root, but only for radeon?

[Dan Kegel]

I tried
lxc.aa_profile = unconfined
but it didn't seem to help.

So I guess I'll live with running X as root for the moment
(and with having to recreate those /dev entries on every boot,
what's up with that?)


On Tue, Sep 13, 2016 at 3:33 PM, Dan Kegel <dank at kegel.com> wrote:
> Hey all,
> I'm running X inside lxc containers on ubuntu 16.04.
> The script I'm using to tweak lxc configuration to support X is
> http://kegel.com/linux/lxc-opengl-demo/install-x.sh.txt
> Seems to work fine for intel and nvidia, but for amd graphics (two
> different systems so far), it complains
>   Fatal server error: AddScreen/ScreenInit failed for driver 0
> strace shows that X can't open /proc/mtrr.
> Running startx as root works around the problem, but that shouldn't be needed.
> Can I buy a clue here?   Thanks!
> - Dan
>
> p.s. To reproduce:
>
> # Bring down X
> host$ sudo systemctl start multi-user.target
> # Create a container, add a user, give him sudo, start in foreground
> host$ sudo lxc-create -n video -t download  -- --dist ubuntu --release
> xenial --arch amd64
> host$ wget http://kegel.com/linux/lxc-opengl-demo/install-x.sh
> host$ sudo sh install-x.sh host video
> host$ sudo lxc-start -n vdeo
> host$ sudo lxc-attach -n video adduser fred
> host$ sudo lxc-attach -n video vi /etc/group  # add fred to sudo group
> # Restart the container in the foreground
> host$ sudo lxc-stop -n vdeo
> host$ sudo lxc-start -n video -F
> # Log in to the guest as user fred, then:
> video$ wget http://kegel.com/linux/lxc-opengl-demo/install-x.sh
> # Alas, you have to run install-x.sh guest every time you start the
> container, to recreate /dev stuff.
> video$ sudo sh install-x.sh guest
> # Only if you're using nvidia hardware: Install nvidia driver that
> matches outer host.  Careful.  e.g.
> #video$ sudo apt install nvidia-340
> # Finally, start x in the container
> video$ echo "exec xterm" > .xinitrc
> video$ startx -- vt9
>
> This should give you an xterm with working keyboard and mouse, capable
> of running glxgears, etc.