How to Install Ubuntu11.04 on Mac mini

This guide will explain how to install Ubuntu 11.04 on an external USB HDD.

1. Download and install rEFIt under OSX.
2. Insert Ubuntu Installation CD to an external USB CD drive.
3. Reboot and hold Alt key to boot from the CD drive.
4. Before installing Ubuntu, press F6 and select each options except the last one.
Some options, noapci nopic nomodeset, should be turned off otherwise Linux will halt during the installation.There options would be disabled as well after the installation.

5. Install Ubuntu on the USB HDD drive and do remember to install grub on the USB HDD as well.
6. After the first reboot of installation, rEFIt should detect Linux.
7. Choice to boot from Linux, GRUB will be loaded.
8. Press "E" to edit boot options of GRUB.
Find and add options to Linux boot arguments:

linux /boot/vmlinuz-2.6.32-24-generic \
root=UUID=xxxx-xxx-xxx-xxxx ro quiet \
nosplash noapci nopci nomodeset reboot=apci

Press Ctrl+X to boot Ubuntu after the modification.

9. Install NVIDIA proprietary driver to enable 3D/OpenGL.
10. Enjoy Ubuntu 11.04.

How to transfer Ununtu11.04/Pandaboard to USB HDD

The pre-built Ubuntu 11.04/Pandaboard image is designed to be installed on a SD card. It could be transfer to the USB HDD with some extra efforts. Typically, a bootable OMAP4/Ubuntu SD card contains two partitions: boot and rootfs. Only rootfs should immigrate to a USB drive since Pandaboard requires booting form SD card.

1. Prepares a bootable Ubuntu11.04 SD card. howto
2. Create a ext3/4 partition on a USB HDD labeled "ubuntu".

# /dev/sdXX should be the partition to be formatted,
# for example /dev/sdc2
$ sudo mkfs.ext3 -L ubuntu /dev/sdXX

3. Copy rootfs on the SD card to USB HDD

# Suppose USB is mounted on /mnt/ubuntu
# and rootfs of SD is on /mnt/sd
$ cd /mnt/ubuntu
$ sudo cp -a /mnt/sd/* .

4. Boot from SD card
In order to mount USB HDD as rootfs, It'd update parameters that passed to the kernel. The configuration file is located at /boot/boot.script

$ sudo vi /boot/boot.script

You'd find bootargs have something like this:

root=UUID=XXXX-XXXX-XXXX-XXXX

Replace it to

root=LABEL=ubuntu

Then update boot.scr for uboot using:

$ sudo flash-kernel

5. Reboot it and Ubuntu should use USB HDD as root filesystem. :)