mktemp: failed to create file via template ‘/tmp/serverauth.XXXXXXXXXX’: Permission denied
xauth:  file  does not exist
xauth:  unable to link authority file , use -n
use: X [:<display>] [option]
-a #                   default pointer acceleration (factor)
-ac                    disable access control restrictions
-audit int             set audit trail level
-auth file             select authorization file
...
Initializing built-in extension DRI2
Loading extension GLX
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Error:            Cannot open "/tmp/filegRxhGH" to write keyboard description
>                   Exiting
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Error:            Cannot open "/tmp/fileb9Lgzg" to write keyboard description
>                   Exiting
XKB: Failed to compile keymap
Keyboard initialization failed. This could be a missing or incorrect setup of xkeyboard-config.
(EE)
Fatal server error:
(EE) Failed to activate core devices.(EE)
(EE)
Please consult the The X.Org Foundation support
         at http://wiki.x.org
 for help.
(EE) Please also check the log file at "/var/log/Xorg.1.log" for additional information.
(EE)
(II) AIGLX: Suspending AIGLX clients for VT switch
(EE) Server terminated with error (1). Closing log file.
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: unexpected signal 2

root@blackbox:~# df -h
Filesystem      Size  Used Avail Use% Mounted on
/dev/sda6        22G   18G  2.9G  87% /
none            4.0K     0  4.0K   0% /sys/fs/cgroup
udev            1.9G  4.0K  1.9G   1% /dev
tmpfs           376M  1.2M  374M   1% /run
none            5.0M     0  5.0M   0% /run/lock
none            1.9G  4.0K  1.9G   1% /run/shm
none            100M  4.0K  100M   1% /run/user

root@blackbox:~# ls /home/florian/.Xauthority -al
-rw------- 1 root root 155 Mar 23 17:10 /home/florian/.Xauthority

xauth:  timeout in locking authority file /home/florian/.Xauthority
...
Loading extension GLX
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
>                   Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
>                   Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Compat map for group 2 redefined
>                   Using new definition
> Warning:          Compat map for group 3 redefined
>                   Using new definition
> Warning:          Compat map for group 4 redefined
>                   Using new definition
Errors from xkbcomp are not fatal to the X server
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Warning:          Type "ONE_LEVEL" has 1 levels, but <RALT> has 2 symbols
>                   Ignoring extra symbols
Errors from xkbcomp are not fatal to the X server
(II) AIGLX: Suspending AIGLX clients for VT switch
xinit: connection to X server lost
^M
waiting for X server to shut down (EE) Server terminated successfully (0). Closing log file.

xinit: unexpected signal 2
xauth:  timeout in locking authority file /home/florian/.Xauthority

sudo rm /home/florian/.Xauthority