Kernel panic - not syncing: VFS: unable to mount root fs on unknown-block (0,0)

[mastapat11]

I updated my system to Ubuntu 11.10 (oneiric). I have kernel 3.0.0-12.20.
The system won't start with this new version. I get always the same message (see below).
For the moment I am starting with Kernel 2.6.38-12.51

Kernel panic - not syncing: VFS: unable to mount root fs on unknown-bolock (0,0)
Pid: 1, comm: swapper not tainted 3.0.0-12-generic #20-ubuntu
Call Trace:
panic+0x91/0x/94
mount_block_root+0xdc/0x180
mount_root+0x54/0x59
prepare_namespace+0x16d/0x1af
kernel_init+0x140/0x145
kernel_threat_helper+0x4/0x10
?start_kernel+0x3df/0x3df
?gs_change+0x13/0x13

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-3.0.0-12-generic 3.0.0-12.20
ProcVersionSignature: Ubuntu 2.6.38-12.51-generic 2.6.38.8
Uname: Linux 2.6.38-12-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.23.
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: pat 3754 F.... pulseaudio
 /dev/snd/controlC2: pat 3754 F.... pulseaudio
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info:
 Card hw:0 'Intel'/'HDA Intel at 0xfaef8000 irq 46'
   Mixer name : 'Realtek ALC1200'
   Components : 'HDA:10ec0888,102802b7,00100101'
   Controls : 34
   Simple ctrls : 20
Card1.Amixer.info:
 Card hw:1 'pcsp'/'Internal PC-Speaker at port 0x61'
   Mixer name : 'PC-Speaker'
   Components : ''
   Controls : 4
   Simple ctrls : 3
Card2.Amixer.info:
 Card hw:2 'U0x46d0x8d7'/'USB Device 0x46d:0x8d7 at usb-0000:00:1d.2-2, full speed'
   Mixer name : 'USB Mixer'
   Components : 'USB046d:08d7'
   Controls : 3
   Simple ctrls : 2
Card3.Amixer.info:
 Card hw:3 'Generic'/'HD-Audio Generic at 0xfbffc000 irq 47'
   Mixer name : 'ATI R6xx HDMI'
   Components : 'HDA:1002aa01,00aa0100,00100200'
   Controls : 4
   Simple ctrls : 1
Card3.Amixer.values:
 Simple mixer control 'IEC958',0
   Capabilities: pswitch pswitch-joined penum
   Playback channels: Mono
   Mono: Playback [on]
Date: Mon Oct 31 06:20:29 2011
HibernationDevice: RESUME=UUID=b72e3b1a-a54f-4361-ba88-fa6093b8f156
IwConfig: Error: [Errno 2] No such file or directory
MachineType: DELL Inc. Studio XPS 435T/9000
ProcEnviron:
 PATH=(custom, user)
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: root=UUID=6d6b9dd3-3d38-4fee-9c03-9290309246d1 ro quiet splash
RelatedPackageVersions:
 linux-restricted-modules-2.6.38-12-generic N/A
 linux-backports-modules-2.6.38-12-generic N/A
 linux-firmware 1.60
RfKill: Error: [Errno 2] No such file or directory
SourcePackage: linux
UdevDb: Error: [Errno 2] No such file or directory
UpgradeStatus: Upgraded to oneiric on 2011-10-31 (0 days ago)
dmi.bios.date: 07/28/2009
dmi.bios.vendor: DELL INC.
dmi.bios.version: A16
dmi.board.name: 0X501H
dmi.board.vendor: DELL Inc.
dmi.board.version: A02
dmi.chassis.type: 3
dmi.chassis.vendor: DELL Inc.
dmi.modalias: dmi:bvnDELLINC.:bvrA16:bd07/28/2009:svnDELLInc.:pnStudioXPS435T/9000:pvr00:rvnDELLInc.:rn0X501H:rvrA02:cvnDELLInc.:ct3:cvr:
dmi.product.name: Studio XPS 435T/9000
dmi.product.version: 00
dmi.sys.vendor: DELL Inc.

[Brad Figg (brad-figg)]

Thank you for taking the time to file a bug report on this issue.

However, given the number of bugs that the Kernel Team receives during any development cycle it is impossible for us to review them all. Therefore, we occasionally resort to using automated bots to request further testing. This is such a request.

We have noted that there is a newer version of the development kernel than the one you last tested when this issue was found. Please test again with the newer kernel and indicate in the bug if this issue still exists or not.

If the bug still exists, change the bug status from Incomplete to Confirmed. If the bug no longer exists, change the bug status from Incomplete to Fix Released.

Thank you for your help, we really do appreciate it.

[mastapat11 (trackp200)]

problem solved:

I made some unrelated changes to menu.lst then did an update-grub.
To my surprise, in the diff it showed adding the line: "initrd /initrd.img-3.0.0-12-generic"
Apparently, during the upgrade from natty, the installer 'forgot' to add this very cruical line and i hadn't noticed.
all is good now (except that boot time takes an extra 90s bcuz its waiting for the network to come up, but it does that an all my kernels, so i'll have to file a sep bug for that).

[mastapat11 (trackp200)]

found the missing line. not sure to set status to commited or released?