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10. Configuring the Bootloader

• Making your Choice
• Using yaBoot
• Using yaboot on IBM hardware
• Rebooting the System

10.a. Making your Choice

Introduction

Now that your kernel is configured and compiled and the necessary system configuration files are filled in correctly, it is time to install a program that will fire up your kernel when you start the system. Such a program is called a bootloader.

On Linux/PPC64 we have only yaBoot as a bootloader until grub2 is finished.

10.b. Using yaBoot

Introduction

There are two ways to configure yaBoot for your system. You can use the new and improved yabootconfig included with yaboot-1.3.8-r1 and later to automatically set up yaboot. If for some reason you do not want to run yabootconfig to automatically set up /etc/yaboot.conf or you are installing Gentoo on a G5 (on which yabootconfig does not always work), you can just edit the sample file already installed on your system.

# emerge hfsutils hfsplusutils

(64bit userland)
# emerge --update yaboot-static
(32bit userland)
# emerge --update yaboot

• Default: Using yabootconfig
• Alternative: Manual yaBoot Configuration

Default: Using yabootconfig

yabootconfig will auto-detect the partitions on your machine and will set up dual and triple boot combinations with Linux, Mac OS, and Mac OS X.

To use yabootconfig, your drive must have a bootstrap partition, and /etc/fstab must be configured with your Linux partitions. Both of these should have been done already in the steps above. To start, ensure that you have the latest version of yaboot installed by running emerge --update yaboot-static. This is necessary as the latest version will be available via Portage, but it may not have made it into the stage files.

Now run yabootconfig. The program will run and it will confirm the location of the bootstrap partition. Type Y if it is correct. If not, double check /etc/fstab. yabootconfig will then scan your system setup, create /etc/yaboot.conf and run mkofboot for you. mkofboot is used to format the bootstrap partition, and install the yaboot configuration file into it.

You might want to verify the contents of /etc/yaboot.conf. If you make changes to /etc/yaboot.conf (like setting the default/boot OS), make sure to rerun ybin -v to apply changes to the bootstrap partition.

Now continue with Rebooting your System.

Alternative: Manual yaBoot Configuration

Below you find a completed yaboot.conf file. Alter it at will.

## /etc/yaboot.conf
##
## run: "man yaboot.conf" for details. Do not make changes until you have!!
## see also: /usr/share/doc/yaboot/examples for example configurations.
##
## For a dual-boot menu, add one or more of:
## bsd=/dev/sdaX, macos=/dev/sdaY, macosx=/dev/sdaZ

## our bootstrap partition:

boot=/dev/sda2

## ofboot is the Open Firmware way to specify the bootstrap partition.
## If this isn't defined, yaboot fails on the G5 and some G4s (unless 
## you pass the necessary arguments to the mkofboot/ybin program).
## hd:X means /dev/sdaX.

ofboot=hd:2

## hd: is open firmware speak for sda
device=hd:

delay=5
defaultos=macosx
timeout=30
install=/usr/lib/yaboot/yaboot
magicboot=/usr/lib/yaboot/ofboot

#################
## This section can be duplicated if you have more than one kernel or set of
## boot options - replace kernel-2.6.24-gentoo-r5 with your kernel-version
#################
image=/boot/kernel-2.6.24-gentoo-r5
  label=Linux
  root=/dev/sda3
  partition=3
  read-only

macos=hd:13
macosx=hd:12
enablecdboot
enableofboot

Once yaboot.conf is set up the way you want it, you run mkofboot -v to install the settings in the bootstrap partition. Don't forget this! Confirm when mkofboot asks you to create a new filesystem.

If all goes well, and you have the same options as the sample above, your next reboot will give you a simple, five-entry boot menu. If you update your yaboot config later on, you'll just need to run ybin -v to update the bootstrap partition - mkofboot is for initial setup only.

For more information on yaboot, take a look at the yaboot project. For now, continue the installation with Rebooting your System.

10.c. Using yaboot on IBM hardware

On IBM hardware you cannot run yabootconfig or ybin. You must proceed with the following steps:

• Install yaboot-static
• Run dd if=/usr/lib/yaboot/yaboot.chrp of=/dev/sdXX (fill in XX with your disk and partition for the PReP partition; this was in our example /dev/sda1)
• Next construct your own yaboot.conf file and place into /etc. (Take a look at the config above, look into the man page of yaboot.conf or look at the below yaboot.conf example.)
• Assuming your boot device in OF is pointing to the harddrive you prep boot partition is on then it'll just work, otherwise at IPL time, go into the multiboot menu and set the boot device to the one with your prep boot partition
• That's it!

device=disk:
partition=2
root=/dev/sda2
default=linux
timeout=50

image=/boot/kernel-2.6.24-gentoo-r5
      label=linux
      append="console=ttyS0,9600"
      read-only

For POWER4, POWER5, and blade-based hardware where the PReP disk partition and the disk partition that contains your kernel are on the same physical disk, you can use a simplified yaboot.conf. The following should be sufficient:

default = linux
timeout = 100
image=/boot/kernel-2.6.24-gentoo-r5
      label=linux
      read-only
      root = /dev/sda2
      append="root=/dev/sda2"

To verify that yaboot has been copied to the PReP partition:

# dd if=/dev/sda1 count=10 | grep ELF
Binary file (standard input) matches
10+0 records in
10+0 records out

A match signifies that yaboot was installed correctly.

10.d. Rebooting the System

Exit the chrooted environment and unmount all mounted partitions. Then type in that one magical command you have been waiting for: reboot.

# exit
~# cd
~# umount /mnt/gentoo/boot /mnt/gentoo/dev /mnt/gentoo/proc /mnt/gentoo
~# reboot

Of course, don't forget to remove the bootable CD, otherwise the CD will be booted again instead of your new Gentoo system.

Once rebooted in your Gentoo installation, finish up with Finalizing your Gentoo Installation.

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