Comment 6 for bug 1236642

Here is my grub.cfg.

I'm still trying to figure out how to run update-initramfs when booted from Ubuntu 13.04.

It seems to be the chicken and egg problem. From 13.04 when connected into the / directory of the 13.10 partition, I get:

sudo update-initramfs -c -k 3.11.0-11-generic
[sudo] password for frohro:
update-initramfs: Generating /boot/initrd.img-3.11.0-11-generic
grep: /boot/config-3.11.0-11-generic: No such file or directory
WARNING: missing /lib/modules/3.11.0-11-generic
Device driver support needs thus be built-in linux image!
ERROR: could not open directory /lib/modules/3.11.0-11-generic: No such file or directory
FATAL: could not search modules: No such file or directory
WARNING: could not open /tmp/mkinitramfs_Uhii5Q/lib/modules/3.11.0-11-generic/modules.order: No such file or directory
WARNING: could not open /tmp/mkinitramfs_Uhii5Q/lib/modules/3.11.0-11-generic/modules.builtin: No such file or directory

and when I use the -b ./boot option I get the same thing.