3 febootstrap-supermin-helper - Reconstruct initramfs from supermin appliance.
7 febootstrap-supermin-helper supermin.img hostfiles.txt host_cpu kernel initrd
8 febootstrap-supermin-helper input [...] host_cpu kernel initrd
10 febootstrap-supermin-helper -f ext2 input [...] host_cpu kernel initrd appliance
12 febootstrap-supermin-helper -f checksum input [...] host_cpu
16 I<febootstrap-supermin-helper> reconstructs a bootable kernel and
17 initramfs from a supermin appliance. First you should be familiar
18 with L<febootstrap(8)>.
22 Of the required parameters, the first few are I<input> files, and the
23 last two or three are I<output> files.
25 C<supermin.img> and C<hostfiles.txt> are the input files which
26 describe the supermin appliance. (You can also use a directory name
27 here which is searched for files).
29 C<host_cpu> should be the host CPU, eg. C<x86_64> or C<i686>.
31 C<kernel>, C<initrd> and C<appliance> are the temporary output files
32 that this script produces. These output files are meant to be used
33 just for booting the appliance, and should be deleted straight
34 afterwards. The extra C<appliance> parameter is only required when
35 the format is C<ext2>. None of these parameters are needed for
36 the checksum output C<-f checksum>.
46 Select the output format for the appliance. Possible formats are:
52 A Linux initramfs. This is the default.
54 In this case you have to supply names for the C<kernel>
55 and C<initrd>, where the C<initrd> is the appliance.
61 In this case you have to supply names for the C<kernel>, a small
62 C<initrd> which is used just to locate the appliance, and the
63 C<appliance> (the ext2 filesystem).
69 This prints a checksum which only changes when one of the input files
72 You can use this in order to cache the output of a previous run of
73 this program: computing the checksum is much quicker than building an
74 appliance, and you only need to invalidate the cache (and consequently
75 rebuild the appliance) when the checksum changes. Note that the
76 host_cpu and the UID of the current user are included in the checksum.
84 If this option is specified, then C<file> should be a list of
85 wildcards matching kernel module names, eg:
91 In this case, only kernel modules matching those wildcards will be
92 included in the output appliance. Note: You must resolve any
93 dependencies yourself as this does not pull in dependent modules
96 If this option is not specified, then every kernel module from the
97 host will be included. This is safer, but can produce rather large
98 appliances which need a lot more memory to boot.
106 =item B<--group group>
108 Run febootstrap-supermin-helper as an alternate user and/or group.
109 C<user> and C<group> can be specified as either a name, which will
110 be resolved using the system name service, or a uid/gid. Use of these
111 options requires root privileges.
113 Use of these options is required if running febootstrap-supermin-helper
114 as root with the effective uid/gid set to non-root. Bash will reset
115 the effective uid/gid to the real uid/gid when invoked. As
116 febootstrap-supermin-helper uses bash in parts, this will result in the
117 creation of an appliance with a mixture of ownerships.
123 In libguestfs, on a mid-range Intel-based PC, we reconstruct the
124 initramfs using this script in around 1/5th of a second (assuming a
125 "hot cache" - it's rather slower when run the first time on a cold
128 Some tips to improve performance:
134 Use a kernel module whitelist (the C<--kmods> option), and only
135 list the kernel modules you really need.
139 Minimize the appliance, removing as much extraneous junk as possible.
143 =head1 ENVIRONMENT VARIABLES
147 =item FEBOOTSTRAP_KERNEL
149 If this environment variable is set, then automatic selection of the
150 kernel is bypassed and this kernel is used.
152 The environment variable should point to a kernel file,
153 eg. C</boot/vmlinuz-3.0.x86_64>
155 The corresponding module path is guessed from the kernel name, but you
156 can override that by setting C<FEBOOTSTRAP_MODULES>.
158 =item FEBOOTSTRAP_MODULES
160 If C<FEBOOTSTRAP_KERNEL> and C<FEBOOTSTRAP_MODULES> are both set, then
161 automatic selection of the kernel is bypassed and the kernel and
162 module path are set to these values.
164 The environment variable should point to a module directory,
165 eg. C</lib/modules/3.0.x86_64/>
167 This has no effect if C<FEBOOTSTRAP_KERNEL> is not set.
177 Richard W.M. Jones <rjones @ redhat . com>
181 (C) Copyright 2009-2011 Red Hat Inc.,
182 L<http://people.redhat.com/~rjones/febootstrap>.
184 This program is free software; you can redistribute it and/or modify
185 it under the terms of the GNU General Public License as published by
186 the Free Software Foundation; either version 2 of the License, or
187 (at your option) any later version.
189 This program is distributed in the hope that it will be useful,
190 but WITHOUT ANY WARRANTY; without even the implied warranty of
191 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
192 GNU General Public License for more details.
194 You should have received a copy of the GNU General Public License
195 along with this program; if not, write to the Free Software
196 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.