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)>, L<febootstrap-to-initramfs(8)> and
19 L<febootstrap-to-supermin(8)>.
23 Of the required parameters, the first few are I<input> files, and the
24 last two or three are I<output> files.
26 C<supermin.img> and C<hostfiles.txt> are the input files which
27 describe the supermin appliance. (You can also use a directory name
28 here which is searched for files).
30 C<host_cpu> should be the host CPU, eg. C<x86_64> or C<i686>.
32 C<kernel>, C<initrd> and C<appliance> are the temporary output files
33 that this script produces. These output files are meant to be used
34 just for booting the appliance, and should be deleted straight
35 afterwards. The extra C<appliance> parameter is only required when
36 the format is C<ext2>. None of these parameters are needed for
37 the checksum output C<-f checksum>.
43 =item B<-f fmt> | B<--format fmt>
45 Select the output format for the appliance. Possible formats are:
51 A Linux initramfs. This is the default.
53 In this case you have to supply names for the C<kernel>
54 and C<initrd>, where the C<initrd> is the appliance.
60 In this case you have to supply names for the C<kernel>, a small
61 C<initrd> which is used just to locate the appliance, and the
62 C<appliance> (the ext2 filesystem).
68 This prints a checksum which only changes when one of the input files
71 You can use this in order to cache the output of a previous run of
72 this program: computing the checksum is much quicker than building an
73 appliance, and you only need to invalidate the cache (and consequently
74 rebuild the appliance) when the checksum changes. Note that the
75 host_cpu and the UID of the current user are included in the checksum.
79 =item B<-k file> | B<--kmods file>
81 If this option is specified, then C<file> should be a list of
82 wildcards matching kernel module names, eg:
88 In this case, only kernel modules matching those wildcards will be
89 included in the output appliance. Note: You must resolve any
90 dependencies yourself as this does not pull in dependent modules
93 If this option is not specified, then every kernel module from the
94 host will be included. This is safer, but can produce rather large
95 appliances which need a lot more memory to boot.
101 In libguestfs, on a mid-range Intel-based PC, we reconstruct the
102 initramfs using this script in around 1/5th of a second (assuming a
103 "hot cache" - it's rather slower when run the first time on a cold
106 Some tips to improve performance:
112 Use a kernel module whitelist (the C<--kmods> option), and only
113 list the kernel modules you really need.
117 Minimize the appliance, removing as much extraneous junk as possible.
119 As well as using L<febootstrap-minimize(8)> it is worth checking for
120 anything that is not necessary for your particular application and
128 L<febootstrap-to-initramfs(8)>,
129 L<febootstrap-to-supermin(8)>.
133 Richard W.M. Jones <rjones @ redhat . com>
137 (C) Copyright 2009-2010 Red Hat Inc.,
138 L<http://people.redhat.com/~rjones/febootstrap>.
140 This program is free software; you can redistribute it and/or modify
141 it under the terms of the GNU General Public License as published by
142 the Free Software Foundation; either version 2 of the License, or
143 (at your option) any later version.
145 This program is distributed in the hope that it will be useful,
146 but WITHOUT ANY WARRANTY; without even the implied warranty of
147 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
148 GNU General Public License for more details.
150 You should have received a copy of the GNU General Public License
151 along with this program; if not, write to the Free Software
152 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.