Comment 45 for bug 1038055

Hm, I think that might be missing hint. I have a ssh server running to log in that way (using the nomodeset and the vt could be installed in the broken state). And I stumbled into the working state again. Comparing the xorg.log files I found that when things work, the cirrus module seems to have finished loading and prevents the cirrus x-driver from getting active:

[ 11.447] (EE) cirrus: The PCI device 0xb8 at 00@00:02:0 has a kernel module claiming it.
[ 11.447] (EE) cirrus: This driver cannot operate until it has been unloaded.
...
[ 11.448] (II) modesetting(0): Creating default Display subsection in Screen section
        "Default Screen Section" for depth/fbbpp 24/24
[ 11.448] (==) modesetting(0): Depth 24, (==) framebuffer bpp 24

However in the case where lightdm works but switching to a text console does not, there was a problem with drm device:

[ 12.015] (EE) open /dev/dri/card0: No such file or directory
[ 12.016] (EE) open /dev/fb0: No such file or directory
...
[ 12.018] (II) CIRRUS(0): initializing int10
[ 12.020] (II) CIRRUS(0): Primary V_BIOS segment is: 0xc000
[ 12.020] (II) CIRRUS(0): Creating default Display subsection in Screen section
        "Default Screen Section" for depth/fbbpp 24/24
[ 12.020] (--) CIRRUS(0): Depth 24, (==) framebuffer bpp 24

Looking at the syslog for cirrus, the current (good) run has

Sep 5 12:05:28 ubuntu-virtual-machine kernel: [ 8.609150] fb: conflicting fb hw usage cirrusdrmfb vs EFI VGA - removing generic driver
Sep 5 12:05:28 ubuntu-virtual-machine kernel: [ 8.667602] fbcon: cirrusdrmfb (fb0) is primary device
Sep 5 12:05:28 ubuntu-virtual-machine kernel: [ 8.674590] fb0: cirrusdrmfb frame buffer device
Sep 5 12:05:28 ubuntu-virtual-machine kernel: [ 8.674599] [drm] Initialized cirrus 1.0.0 20110418 for 0000:00:02.0 on minor 0

but the previous (bad) one had this:

Sep 5 11:57:51 ubuntu-virtual-machine kernel: [ 9.838015] fb: conflicting fb hw usage cirrusdrmfb vs EFI VGA - removing generic driver
Sep 5 11:57:51 ubuntu-virtual-machine kernel: [ 9.865736] [drm:cirrus_vram_init] *ERROR* can't reserve VRAM
Sep 5 11:57:51 ubuntu-virtual-machine kernel: [ 9.865757] cirrus 0000:00:02.0: Fatal error during GPU init: -6

Now need to find out why this fails sometimes.