ISST-KVM:R2-0:No login prompt displayed on FB console after Ubuntu 14.10 installation

== Comment: #0 - Richard M. Scheller <email address hidden> - 2014-10-06 13:42:47 ==
---Problem Description---
After installing Ubuntu 14.10 (3.16.0-20-generic kernel) using a qemu virtual VGA framebuffer console and rebooting the installed system, there is no login prompt displayed on the fb console. This is a regression from 14.04.1, where the login prompt is displayed on the console.

(Note that this is *not* related to IBM bug#113591/LauchPad bug#1346851, which has been fixed in the latest daily builds.)

The OS installation completes without any errors, then the guest reboots from the installed virtual disk. The guest comes up without any problems (it is possible to ssh into the guest) but no login prompt is displayed on the fb console.

Machine Type = 8247-22L (PowerKVM guest)

---Steps to Reproduce---
 Configure guest with framebuffer console and USB keyboard/mouse and install through that interface.

---uname output---
Linux netg7 3.16.0-20-generic #27-Ubuntu SMP Wed Oct 1 17:24:38 UTC 2014 ppc64le ppc64le ppc64le GNU/Linux

---Debugger---
A debugger is not configured

Install ISO Information: 2014-10-06 daily build (network install)

Install disk info: n/a

Install method: TFTP boot of kernel/initrd from local server, then direct download from ports.ubuntu.com

== Comment: #4 - Richard M. Scheller <email address hidden> - 2014-10-06 14:34:43 ==
I should also point out that there is no login prompt displayed on the virtual serial console (/dev/hvc0) either. Here is a list of the getty processes which are started on reboot:

root@netg7:~# ps -ef|grep getty|grep -v grep
root 869 1 0 12:23 tty4 00:00:00 /sbin/getty -8 38400 tty4
root 871 1 0 12:23 tty5 00:00:00 /sbin/getty -8 38400 tty5
root 874 1 0 12:23 tty2 00:00:00 /sbin/getty -8 38400 tty2
root 875 1 0 12:23 tty3 00:00:00 /sbin/getty -8 38400 tty3
root 881 1 0 12:23 tty6 00:00:00 /sbin/getty -8 38400 tty6
root 1026 1 0 12:23 tty1 00:00:00 /sbin/getty -8 38400 tty1
root@netg7:~#

== Comment: #10 - Richard M. Scheller <email address hidden> - 2014-10-06 17:31:23 ==
OK, I think I'm getting closer to the root cause. I'm pretty sure it's the framebuffer device.

These are the related kernel messages from Ubuntu 14.04.1 (netg9):

root@netg9:~# dmesg|egrep -i 'buffer|offb|vga'
[ 0.099978] vgaarb: device added: PCI:0000:00:05.0,decodes=io+mem,owns=io+mem,locks=none
[ 0.099979] vgaarb: loaded
[ 0.099980] vgaarb: bridge control possible 0000:00:05.0
[ 0.581438] Using unsupported 800x600 vga at 100a0000000, depth=32, pitch=3200
[ 0.583419] Console: switching to colour frame buffer device 100x37
[ 0.584748] fb0: Open Firmware frame buffer device on /pci@800000020000000/vga@5
root@netg9:~#

And here are the related messages from 14.10 (netg7):

root@netg7:~# dmesg|egrep -i 'buffer|offb|vga'
[ 0.136665] vgaarb: device added: PCI:0000:00:05.0,decodes=io+mem,owns=io+mem,locks=none
[ 0.136701] vgaarb: loaded
[ 0.136733] vgaarb: bridge control possible 0000:00:05.0
[ 0.580147] Using unsupported 800x600 vga at 100a0000000, depth=32, pitch=3200
[ 0.583407] Console: switching to colour frame buffer device 100x37
[ 0.585721] fb0: Open Firmware frame buffer device on /pci@800000020000000/vga@5
[ 4.264808] fb: switching to bochsdrmfb from OFfb vga
[ 4.266985] [drm:bochs_hw_init] *ERROR* Cannot request framebuffer
root@netg7:~#

Everything looks pretty much the same on both guests until 14.10 tries to switch to the "bochsdrmfb" device. I'm going to assume that device only works on x86.

On 14.10, the kernel has a new driver that doesn't exist on 14.04:

14.10:
root@netg7:~# grep -i bochs /boot/config-3.16.0-20-generic
CONFIG_DRM_BOCHS=m
root@netg7:~#

14.04.1:
root@netg9:~# grep -i bochs /boot/config-3.13.0-36-generic
root@netg9:~#

== Comment: #11 - Richard M. Scheller <email address hidden> - 2014-10-06 18:28:25 ==
I disabled the bochs framebuffer on 14.10 by adding the following line to /etc/modprobe.d/blacklist.conf:

blacklist bochs-drm

On the next guest reboot, the login prompt appeared on the VGA console as expected and I was able to login interactively through the Kimchi web VNC interface.

So, the problem is definitely the bochs DRM device. I don't know if the appropriate long-term solution is to fix the boch-drm driver or if it should simply be disabled, but one or the other needs to be done for 14.10 and future releases.