---
layout: post
title: How-to boot FreeBSD with Grub2 under Ubuntu 10.10
date: 2010-10-12 09:02
author: rick
categories: ubuntu, freebsd,gpt
---

I recently upgrade to Ubuntu 10.10. Which also caused grub to be updated to version `1.98` (to be exactly `{1.98+201000804-5ubuntu3`), which used a different syntax to define partitions instead of numbers which where off by one, they now use msdosX style formatting.

My FreeBSD is located at /dev/sda3 on a good old MBR partition table and I want to use the good old FreeBSD boot loader as well (so chainloading is required). To activate within Ubuntu. Put the following contents in file:/etc/grub.d/40_custom:

```sh
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "FreeBSD (on /dev/sda3)" {
	savedefault
        insmod chain
	set root='(hd0,msdos3)'
	chainloader +1
}

```

Note: My hd0 is file:/dev/sda under Linux and got named file:/dev/ad6  under FreeBSD
If you want to boot of a GPT partion use the following syntax

```sh
#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
menuentry "FreeBSD (on /dev/ad6p3)" {
	savedefault
        insmod ufs2
	set root='(hd0,gpt3)'
	kfreebsd /boot/loader
}

```

Update your grub and use should be done:
rick-eee$ sudo update-grub