I have ubuntu-12.04 on my virtualbox and I have two kernels in /boot (old and new). When I restart the vbox no grub appears to choose! and the result of cat /proc/cmdline
still shows the old kernel is running.
I tried pressing shift but it also does not work!
GRUB_HIDDEN_TIMEOUT
, per http://askubuntu.com/a/16049 – ignis Jul 01 '13 at 10:52