Comment 137 for bug 477104

Same problem here after 2.6.31-19 kernel upgrade. At first I had enduring trouble and great pain booting manually, and I wanted to share the instructions that worked for my system.

The greatest point of confusion for me was that there were no /dev/sd... entries listed via "ls /dev" from the grub command prompt. Despite this, my manual boot succeeded when I used "root=/dev/sda2". in my "linux ..." command. Also, my host (vista) partition was not mounted properly, so I could not "ls /ubuntu". Yet despite that I was able to successfully specify "loop=/ubuntu/disks/root.disk" in my linux command.

System details:
hardware: lenovo r61i laptop (probably not relevant)
host OS: Windows Vista
wubi version: ? (probably not relevant)
ubuntu version: 9.10

Manual boot instructions:
set root=(loop0)
linux /boot/vmlinuz-2.6.31-16-generic root=/dev/sda2 loop=/ubuntu/disks/root.disk ro
initrd /boot/initrd.img-2.6.31-16-generic
boot

In Ubuntu after manual root:
"sudo update-grub" ("sudo update-grub2" is equivalent?)

Notes:
You may have to change /dev/sda2 to /dev/sda1. You need to pick the device that corresponds to the windows partition that stores your wubi installation. I think I simply used "ls" from the grub command prompt and got info that suggested I needed to use sda2. (I think the first partition was the windows boot partition).