13.3. Making the CLFS System Bootable

Your shiny new CLFS system is almost complete. One of the last things to do is to ensure that the system can be properly booted. The instructions below apply only to NewWorld Macintoshes.

Boot loading can be a complex area, so a few cautionary words are in order. Be familiar with the current boot loader and any other operating systems present on the hard drive(s) that need to be bootable. Make sure that an emergency CD is ready to “rescue” the computer if it becomes un-bootable. It is also a good idea to enable booting from Open Firmware in case things go really wrong.

Earlier, we compiled and installed the yaboot boot loader software in preparation for this step. The procedure involves writing the bootloader to a bootstrap partition and blessing it so that Open Firmware will boot from it. This is all handled by ybin, the yaboot installer.

Ybin writes an optional 'OS selector' menu into Open Firmware, then writes yaboot and yaboot.conf to the bootstrap partition, blesses this, and updates the boot device recorded in nvram. When booted, the OF provides the initial menu to choose between linux, boot from CD, and e.g. OSX (depending on what was in yaboot.conf). If you boot to 'linux', yaboot is executed and lets you select which kernel to use.

Images (kernels) are specified, together with any necessary path, in yaboot.conf - the details are incorporated into the bootloader, but no attempt is made to access or validate the paths until they are selected. There are many possible options that can be specified in yaboot.conf, see the man page for the details. Most people will be able to specify device=hd: (for a single hard disk), but if you have multiple disks, or if you wish to be pedantic, you can specify the full OF path to the device, obtained by running ofpath /dev/hdX .

Using the above information, determine the appropriate designators for the bootstrap partition and the root partition. For the following example, it is assumed that the bootstrap partition is hda2 and the root partition is hda7. We will also assume that you wish to be able to boot an OSX installation on hda4. Change these items as necessary for your machine.

If your machine has a SATA disk, specify the partitions using /dev/sda7 and so forth in the usual way. At least some of the distros specify a full OF path to the 'device' and to the image(s), such as device=/ht@0,f2000000/pci@3/k2-sata-root@c/k2-sata@0/disk@0: for the disk, and image=/ht@0,f2000000/pci@3/k2-sata-root@c/k2-sata@0/disk@0:9,/boot/clfskernel-4.9.21 which definitely works.

Create a “yaboot.conf” file defining yaboot's boot menu:

cat > /etc/yaboot.conf << "EOF"
# Begin /etc/yaboot.conf

# By default, yaboot will boot the first menu entry.

# Allow 10 seconds before booting the default.
# this will also apply to the first-stage os selector
timeout=100

# These variables are global
# first, where to put the bootstrap partition
boot=/dev/hda2

# Which disk to use
device=hd:

# Default partition for the kernel images
partition=7

# default root partition
root=/dev/hda7

# where ybin is to find yaboot and ofboot
install=/usr/lib/yaboot/yaboot
magicboot=/usr/lib/yaboot/ofboot

# allow the initial menu to offer CD as an option
enablecdboot

# allow the initial menu to offer booting from Open Firmware
enableofboot

# allow the initial menu to boot from mac osx
macosx=/dev/hda4

# white on black is boring!
# note  the spellings : 'fgcolor' but 'light'
# in this context, light means 'without high intensity'
fgcolor=light-green

# The first entry is for CLFS.
# For all images, the pathname is relative to the filesystem
# on which they are situated and can include at most one
# directory
image=/boot/clfskernel-4.9.21
    label=SYSVINIT-20170702
    read-only
EOF

Add an entry for the host distribution, if you have one. It might look something like this if the kernel and initrd are in the host's '/' directory on hda6:

cat >> /etc/yaboot.conf << "EOF"
title Debian
image=/pci@f4000000/ata-6d/disk@0:6,/vmlinux
    label=Debian
    initrd=/pci@f4000000/ata-6d/disk@0:6,/initrd.gz
    initrd-size=10000
    append="root=/dev/hda7"
    read-only
EOF

ybin

Alternatively, if the bootstrap partition has not already been initialized, perhaps because you are using a Live CD, you will need to use a different command to install the bootloader for the first time:

mkofboot