=head1 NAME

febootstrap-supermin-helper - Reconstruct initramfs from supermin appliance.

=head1 SYNOPSIS

 febootstrap-supermin-helper supermin.img hostfiles.txt kernel initrd

=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 four parameters, the first two are I<input> files, and the last
two are I<output> files.

C<supermin.img> and C<hostfiles.txt> are the input files which
describe the supermin appliance.

C<kernel> and C<initrd> 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.

=head1 OPTIONS

=over 4

=item 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 Red Hat Inc.,
L<http://et.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.