febootstrap-supermin-helper (8) - Linux Manuals

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


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


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


febootstrap-supermin-helper reconstructs a bootable kernel and initramfs from a supermin appliance. First you should be familiar with febootstrap(8), febootstrap-to-initramfs(8) and febootstrap-to-supermin(8).


Of the four parameters, the first two are input files, and the last two are output files.

"supermin.img" and "hostfiles.txt" are the input files which describe the supermin appliance.

"kernel" and "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.


--kmods file
If this option is specified, then "file" should be a list of wildcards matching kernel module names, eg:


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.


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:

Use a kernel module whitelist (the "--kmods" option), and only list the kernel modules you really need.
Minimize the appliance, removing as much extraneous junk as possible.

As well as using febootstrap-minimize(8) it is worth checking for anything that is not necessary for your particular application and removing it by hand.


Richard W.M. Jones <rjones @ redhat . com>


(C) Copyright 2009 Red Hat Inc., <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.