source: BOOK/appendices/ppc/macmiscellany.xml @ 073fae8

clfs-1.2clfs-2.1clfs-3.0.0-systemdclfs-3.0.0-sysvinitsystemdsysvinit
Last change on this file since 073fae8 was 073fae8, checked in by Jim Gifford <clfs@…>, 13 years ago

r3903@server (orig r1756): ken | 2006-06-09 17:04:23 -0700
First attempt at making the ppc temporary system bootable, plus related cleanups, particularly for creating partitions.

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File size: 6.5 KB
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1<?xml version="1.0" encoding="ISO-8859-1"?>
2<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN"
3  "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd" [
4  <!ENTITY % general-entities SYSTEM "../../general.ent">
5  %general-entities;
6]>
7
8<appendix id="appendixe" xreflabel="Appendix E">
9  <?dbhtml dir="appendices"?>
10  <?dbhtml filename="macmiscellany.html"?>
11
12  <title>Open Firmware and Mac issues.</title>
13
14    <para>This appendix documents some of the features of ppc macintoshes,
15    and in particular the requirements of coexisting with Mac OS's (OSX or
16    the old OS9).  It is only relevant to NewWorld hardware.</para>
17
18  <variablelist>
19
20    <varlistentry>
21      <term><emphasis role="bold">Open Firmware and blessed partitions</emphasis></term>
22      <listitem>
23        <para>The Open Firmware (OF) is the code in ROM or nvram which controls
24        how the machine boots.  If booting automatically, it will boot from the
25        first valid blessed partition it finds (this is a simplification,
26        but it is adequate for normal purposes).</para>
27
28        <para>It can only read apple filesystems (hfs, hfs+, or hfsx depending
29        on the version of the firmware).  For disks under linux, the blessing
30        is done by ybin when it installs yaboot (the loader) and yaboot.conf.</para>
31
32        <para>Mac OS's have a tendency to look at other hfs{,+,x} filesystems
33        on the disk, and unbless them if they do not match their expectations.
34        Unblessing makes them unbootable. Fortunately, a filesystem of type
35        <literal>Apple_Bootstrap</literal> can be read as hfs by the OF, but will
36        be ignored by Mac OS.</para>
37      </listitem>
38    </varlistentry>
39
40    <varlistentry>
41      <term><emphasis role="bold">Partitioning</emphasis></term>
42      <listitem>
43        <para>Macintoshes use their own partition format - this means that other
44        machines are unlikely to be able to read or write to macintosh partitions
45        (in particular, fdisk does not understand them). The format allows a large
46        number of individual partitions, and the native Mac tools had a tendency
47        to insert small "filler" partitions between the real partitions. Under
48        linux, using more than 15 partitions can be problematic (shortage of device
49        nodes), so the normal approach is to use the Mac tools to create an area
50        of freespace at the <emphasis>front</emphasis> of the disk, then put the
51        Mac OS partition(s) after it and (re-)install the Mac OS.  The
52        freespace can then be partitioned using <command>parted</command> or the
53        older <command>mac-fdisk</command>.  It seems that recent versions of the
54        Mac tools may no longer insert the filler partitions, so it may be
55        possible to do all the partitioning before installing OSX.</para>
56
57        <warning>
58        <para>The Macintosh resizing and partitioning tools are destructive and may
59        delete all data when a partition is resized, even on unaltered partitions.
60        </para>
61        </warning>
62
63        <para>For the Linux partitions, you will need a bootstrap partition - this
64        can normally be a mere 800KB in size (the smallest hfs partition available)
65        although the Fedora installer  has been known to insist on 800MB.  This has
66        to be in front of the Mac OS partition.  The bootstrap is
67        <emphasis>never</emphasis> mounted as a regular partition and should not
68        be confused with a <literal>/boot</literal> partition.  Other partitions
69        are as normal (at least one rootfs, perhaps swap, perhaps others).</para>
70
71        <para>According to the lfs-from-osx hint, the Mac partitioning tools
72        can create an apple_bootstrap partition and therefore there is no need
73        to use a Linux CD to create the desired partitions from freespace, but
74        using a Linux CD to create the partitions is a more widely tested approach.
75        </para>
76
77        <para>If you follow this approach, partition 1 will be the apple partition
78        map, partition 2 will be the bootstrap at the start of the disk, the
79        linux partitions will follow, and then the mac partition(s) - under OSX
80        the first mac partition will be number 3, under OS9 it would have a higher
81        number and there would be some apple driver partitions.</para>
82      </listitem>
83    </varlistentry>
84
85    <varlistentry>
86      <term><emphasis role="bold">OSX or OF upgrades</emphasis></term>
87      <listitem>
88        <para>If the machine is dual-booted with OSX, the mac kernel or the OF
89        will probably be upgraded at some point.  This appears to either unbless
90        the bootstrap,  or else just point the OF boot device to the mac partition
91        - so, the linux system will no longer be bootable.</para>
92
93        <para>Therefore, you will need to know which partition contains the bootstrap
94        so that you can boot it from OF (on an apple keyboard, hold down
95        option-command-o-f (that is, alt-apple-o-f) while booting then enter a
96        command like:</para>
97
98<screen><userinput role="nodump">boot hd:2,yaboot</userinput></screen>
99
100        <para>This will allow you to select a linux boot, and from there you
101        will have to rerun <command>ybin</command>.</para>
102
103        <para>The "OS chooser" menu that yaboot typically loads is stored in the
104        OF and will not be available after a Mac kernel or firmware upgrade until
105        <command>ybin</command> has been rerun.</para>
106      </listitem>
107    </varlistentry>
108
109    <varlistentry>
110      <term><emphasis role="bold">Yaboot's requirements</emphasis></term>
111      <listitem>
112        <para>Yaboot is the boot loader for linux, sometimes referred to as
113        the second stage loader.  It reads the yaboot.conf file on the bootstrap
114        partition to find which linux system(s) should be available, and
115        attempts to load the required kernel.</para>
116
117        <para>The bootstrap man page warns that the path to the kernel should
118        contain no more than one directory for reliability.</para>
119
120        <para>Yaboot has to be able to understand the filesystem, so that it
121        can find the kernel.  It understands hfs (not useful for linux, it is
122        not case-sensitive), ext2 (and therefore it can read ext3), reiser3,
123        and xfs.  If you want to use a different type of filesystem for '/'
124        you will have to create a separate boot partition with a supported
125        filesystem, and use that to hold the kernels.</para>
126
127      </listitem>
128    </varlistentry>
129
130    <varlistentry>
131      <term><emphasis role="bold">Requirements if starting from OSX</emphasis></term>
132      <listitem>
133        <para>Older versions of OSX (panther, leopard) can write to ext2
134        filesystems using version 1.3 of ext2fsx.  The upgrade to tiger broke
135        this, and version 1.4 of ext2fsx only supports reading.  Users of
136        current OSX will therefore have to find some other way of creating
137        a suitable filesystem and populating it, such as a Live CD or rescue CD.
138        </para>
139      </listitem>
140    </varlistentry>
141
142  </variablelist>
143
144</appendix>
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