Comment 4 for bug 1440174

I have Ubuntu installed on my 17'' core-duo intel imac, with an encrypted root partition.
Version 12.04 with 13.5.0-17-generic worked ok, but I updated to the LTS version 14.04.
The system now freezes before asking for my encryption password when booting (I am using EFI with grub2)
with my old kernel (13.5.0-17-generic) and with no args on the kernel command line. If I put nomodeset the boot
progresses to the encryption password and I can successfully login, however the video is completely scrambled (I literally cannot
make out anything). Having tried many ways to fix the video, I tried the latest kernel (3.13.0-48-generic). In this case
the boot gets to the password, but the keyboard/mouse does not respond. Again I tried many fixes, unsuccesfully. I installed the extras
so as to have usbhid, mac_hid etc, and found that the behaviour now reverted precisely to that outlined above for 13.5.0-17-generic;
that is scrambled graphics but successful login (with nomodeset), and ok graphics but no keyboard (without nomodeset).
I tried manually adding only the hid modules to my initrd.img-3.13.0-48-generic built prior to install of extra, but found graphics again
ok but still no keyboard !