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=head1 NAME
febootstrap-supermin-helper - Reconstruct initramfs from supermin appliance.
=head1 SYNOPSIS
febootstrap-supermin-helper supermin.img hostfiles.txt host_cpu kernel initrd
febootstrap-supermin-helper input [...] host_cpu kernel initrd
febootstrap-supermin-helper -f ext2 input [...] host_cpu kernel initrd appliance
=head1 DESCRIPTION
I<febootstrap-supermin-helper> reconstructs a bootable kernel and
initramfs from a supermin appliance. First you should be familiar
with L<febootstrap(8)>, L<febootstrap-to-initramfs(8)> and
L<febootstrap-to-supermin(8)>.
=head1 PARAMETERS
Of the required parameters, the first few are I<input> files, and the
last two or three are I<output> files.
C<supermin.img> and C<hostfiles.txt> are the input files which
describe the supermin appliance. (You can also use a directory name
here which is searched for files).
C<host_cpu> should be the host CPU, eg. C<x86_64> or C<i686>.
C<kernel>, C<initrd> and C<appliance> are the temporary output files
that this script produces. These output files are meant to be used
just for booting the appliance, and should be deleted straight
afterwards. The extra C<appliance> parameter is only required when
the format is C<ext2>.
=head1 OPTIONS
=over 4
=item B<-f fmt> | B<--format fmt>
Select the output format for the appliance. Possible formats are:
=over 4
=item cpio
A Linux initramfs. This is the default.
In this case you have to supply names for the C<kernel>
and C<initrd>, where the C<initrd> is the appliance.
=item ext2
An ext2 filesystem.
In this case you have to supply names for the C<kernel>,
a small C<initrd> which is used just to locate the appliance,
and the C<appliance> (the ext2 filesystem).
=back
=item B<-k file> | B<--kmods file>
If this option is specified, then C<file> should be a list of
wildcards matching kernel module names, eg:
virtio*.ko
scsi*.ko
piix.ko
In this case, only kernel modules matching those wildcards will be
included in the output appliance. Note: You must resolve any
dependencies yourself as this does not pull in dependent modules
automatically.
If this option is not specified, then every kernel module from the
host will be included. This is safer, but can produce rather large
appliances which need a lot more memory to boot.
=back
=head1 SPEED
In libguestfs, on a mid-range Intel-based PC, we reconstruct the
initramfs using this script in around 1/5th of a second (assuming a
"hot cache" - it's rather slower when run the first time on a cold
cache).
Some tips to improve performance:
=over 4
=item *
Use a kernel module whitelist (the C<--kmods> option), and only
list the kernel modules you really need.
=item *
Minimize the appliance, removing as much extraneous junk as possible.
As well as using L<febootstrap-minimize(8)> it is worth checking for
anything that is not necessary for your particular application and
removing it by hand.
=back
=head1 SEE ALSO
L<febootstrap(8)>,
L<febootstrap-to-initramfs(8)>,
L<febootstrap-to-supermin(8)>.
=head1 AUTHORS
Richard W.M. Jones <rjones @ redhat . com>
=head1 COPYRIGHT
(C) Copyright 2009-2010 Red Hat Inc.,
L<http://people.redhat.com/~rjones/febootstrap>.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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