http://askubuntu.com/questions/355034/ubuntu-12-04-3-lts-installation-failed-says-grub-installation-failed
http://forum.ubuntu.com.cn/viewtopic.php?f=48&t=446368&p=3019940
the grub-efi-amd64-signed package failed to install into /target/. Without the GRUB bootloader the system will not load
uefi安装，总是报错，当然我肯定设置了efi分区。还是失败，原来这是个bug，晕彩
/pool/main/g/grub2-signed/grub-efi-amd64-signed 1.9~ubuntu12.04.4+1.99-21ubuntu3.10_amd64.deb file rename when you burn it in CD/DVD or usb disk togrub-efi-amd64-signed 1.9~ubuntu12.04.4+1.99-21ubuntu3.10_amd.deb. As a
result installation script can't find the file and failed to install grub. Quick workaround is that(if you burn iso in USB flash drive) go to pool/main/g/grub2-signed(in usb flash disk) and rename the deb file manually (add64). Now boot from
usb flash drive and run a disk check to be sure.