1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
<chapt id="update-hooks">
<heading>Package maintainer scripts and hooks</heading>
<p>
Kernel packages for Debian have historically had complex
maintainer scripts which can invoke the initramfs builder and/or a
boot loader, based on a mixture of file tests, explicit
configuration through the file <tt>/etc/kernel-img.conf</tt> and
debconf questions. Starting with Debian 6.0, this has been greatly
simplified.
</p>
<p>
The following policy applies to Debian GNU/Linux 6.0 'squeeze' and
later releases. Some parts may be applicable to kernels other
than Linux, but this policy does not set any requirements for
them.
</p>
<sect id="kernel-hooks">
<heading>Kernel hooks</heading>
<p>
The maintainer scripts in Linux kernel packages must use
<tt>run-parts</tt> to invoke hook scripts in the corresponding
subdirectory of <tt>/etc/kernel</tt>, e.g. the <tt>postinst</tt>
script must invoke scripts in <tt>/etc/kernel/postinst.d</tt>.
</p>
<p>
The arguments given to all kernel hook scripts are the kernel
ABI version (the string that <tt>uname -r</tt> reports) and,
optionally, the absolute path to the kernel image. If the
second argument is missing then the path is
either <tt>/boot/vmlinuz-<em>version</em></tt> or
<tt>/boot/vmlinux-<em>version</em></tt>, according to
architecture convention. The environment variable
<tt>DEB_MAINT_PARAMS</tt> will contain the arguments given to
the kernel maintainer script, possibly single-quoted. In a
shell script, this variable can be parsed using:
<example>
eval set -- "$DEB_MAINT_PARAMS"
</example>
</p>
<p>
Kernel hook scripts may be run under debconf. In this case
they must not use stdin and stdout, and should send all output
to stderr (fd 2). A shell script can ensure that it does this
using:
<example>
exec </dev/null >&2
</example>
</p>
</sect>
<sect id="kernel-hooks-loader">
<heading>Kernel hooks required for boot loaders</heading>
<p>
Packages for boot loaders that need to be updated whenever the
files they load are modified (i.e. those that store a block
list) must install hook scripts in
<tt>/etc/kernel/postinst.d</tt> and
<tt>/etc/kernel/postrm.d</tt>.
</p>
<p>
Since these boot loaders should be updated as the last step
during installation/upgrade and removal, hook scripts for boot
loaders must be named using the prefix <tt>zz-</tt> and no other
packages may use this prefix or one that sorts later by the
rules used by <tt>run-parts</tt>. A postrm hook script should
warn but exit with code 0 if the boot loader configuration file
still refers to the kernel image that has been removed.
</p>
<p>
These boot loader packages must be installable on the filesystem
in a disabled state where they will not write to the boot sector
or other special storage. While a boot loader is disabled, any
kernel hooks it includes must do nothing except (optionally)
printing a warning that the boot loader is disabled, and must
exit successfully.
</p>
<p>
Packages for boot loaders that can provide a menu of kernel
versions should install kernel hook scripts in order to update
that menu.
</p>
</sect>
<sect id="initramfs-hooks">
<heading>Initramfs hooks</heading>
<p>
Packages for boot loaders that need to be updated whenever the
files they load are modified must also install hook scripts in
<tt>/etc/initramfs/post-update.d</tt>. Initramfs builders
must call these scripts using <tt>run-parts</tt> after they
create, update or delete an initramfs. The arguments given to
these hook scripts are the kernel ABI version and the absolute
path to the initramfs image.
</p>
<p>
While a boot loader is disabled, any initramfs hook it includes
must do nothing except (optionally) printing a warning that the
boot loader is disabled, and must exit successfully.
</p>
</sect>
<sect id="kernel-hooks-initramfs">
<heading>Kernel hooks required for initramfs builders</heading>
<p>
Initramfs builders must install hook scripts in
<tt>/etc/kernel/postinst.d</tt> and
<tt>/etc/kernel/postrm.d</tt>, to create/update and delete the
corresponding initramfs images. The postinst hook script must
complete its work before returning.
</p>
</sect>
<sect id="loader-optimisation">
<heading>Optimising boot loader updates</heading>
<p>
During a kernel package installation, upgrade or removal, various
boot loader hooks may be invoked (in this order):
<enumlist>
<item>
A <tt>postinst_hook</tt> or <tt>postrm_hook</tt> command
set by the user or the installer in
<tt>/etc/kernel-img.conf</tt>
</item>
<item>
A hook script in <tt>/etc/initramfs/post-update.d</tt>
</item>
<item>
A hook script in <tt>/etc/kernel/postinst.d</tt> or
...<tt>/postrm.d</tt>
</item>
</enumlist>
</p>
<p>
To avoid unnecessary updates, the hooks invoked at steps 1 and
2 may check whether <tt>$DPKG_MAINTSCRIPT_PACKAGE</tt> begins
with <tt>linux-image-</tt> and do nothing in this case.
</p>
</sect>
<sect id="deprecation">
<heading>Deprecated features</heading>
<p>
Kernel packages must not invoke boot loaders except via hooks.
If <tt>/etc/kernel-img.conf</tt> contains <tt>do_bootloader =
yes</tt> or equivalent, maintainer scripts that previously
acted on this must warn that they are ignoring
it. <tt>linux-base</tt> must also warn on upgrade that the
default has changed. In Debian 7.0 'wheezy', this prohibition
extends to initramfs builder packages.
</p>
</sect>
<sect id="init-config">
<heading>Initial configuration by the installer</heading>
<p>
The installer must not define <tt>do_bootloader</tt>,
<tt>postinst_hook</tt> or <tt>postrm_hook</tt> in
<tt>/etc/kernel-img.conf</tt>.
</p>
</sect>
</chapt>
|
