source: BOOK/bootable/ppc/yaboot.xml@ e94ed9a

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<sect1 id="ch-bootable-yaboot" arch="ppc">
  <?dbhtml filename="yaboot.html"?>

  <title>Making the LFS System Bootable</title>

  <indexterm zone="ch-bootable-yaboot">
    <primary sortas="a-Yaboot">Yaboot</primary>
  <secondary>configuring</secondary></indexterm>

  <para os="a">Your shiny new LFS 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 and (probably)
  PegasosPPC.</para>

  <para os="b">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 <quote>rescue</quote> the
  computer if it becomes un-bootable.</para>

  <para os="c">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 OpenFirmware will boot from
  it.  This is all handled by <command>ybin</command> the yaboot installer.</para> 

  <para os="d">Ybin assembles all the information it needs by reading yaboot.conf,
  then writes the bootstrap. When booted, the bootstrap provides an 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 kicks in and lets you select which kernel to use.</para>

  <para os="e">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 <command>ofpath</command>.</para>

  <para os="f">Note that the man page mentions which filesystems yaboot can
  navigate to find the images - the only linux filesystem type mentioned is ext2.
  You can use ext3 because that can be read like ext2, but if you wish to use
  reiserfs or any other filesystem you may need to create a separate boot partition
  formatted as ext2.</para>

  <para os="h">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 <filename class="partition">hda2
  </filename> and the root partition is <filename class="partition">hda7</filename>
  .  We will also assume that you wish to be able to boot an OSX installation on
  <filename class="partition">hda4</filename>.  Change these items as necessary
  for your machine.</para>

  <para os="k">Create a <quote>yaboot.conf</quote> file defining yaboot's boot
  menu:</para>

<screen os="l" role="nodump"><userinput>cat &gt; /etc/yaboot.conf &lt;&lt; "EOF"
<literal># 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 boot from mac osx
macosx=/dev/hda4

# The first entry is for LFS.
# For all images, the pathname is relative to the filesystem
# on which they are mounted.
image=/boot/lfskernel-&linux-version;
    label=&version;
    read-only</literal>
EOF</userinput></screen>


  <para os="n">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 <filename class="partition">hda6</filename>:</para>

<screen os="o" role="nodump"><userinput>cat &gt;&gt; /etc/yaboot.conf &lt;&lt; "EOF"
<literal>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</literal>
EOF</userinput></screen>

  <warning os="r">
    <para>The following command will overwrite the current boot loader.
    Do not run the command if this is not desired.</para>
  </warning>

<screen os="s" role="nodump"><userinput>ybin</userinput></screen>

  <para os="t">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:</para>

<screen os="u" role="nodump"><userinput>mkofboot</userinput></screen>

</sect1>