Ubuntu Manpage: supermin-helper - Reconstruct initramfs from supermin appliance.

NAME

       supermin-helper - Reconstruct initramfs from supermin appliance.

SYNOPSIS

       New style (since supermin 4.1.5):

        supermin-helper [-f cpio|ext2] -o outputdir input [input...]

       or:

        supermin-helper [-f cpio|ext2] --output-kernel kernel \
          [--output-dtb dtb] --output-initrd initrd \
          [--output-appliance appliance] input [input...]

       or:

        supermin-helper -f checksum input [input ...]

       Old style (still supported in this version but deprecated):

        supermin-helper [-f cpio] supermin.img hostfiles.txt host_cpu kernel initrd
        supermin-helper [-f cpio] input [...] host_cpu kernel initrd

        supermin-helper -f ext2 input [...] host_cpu kernel initrd appliance

        supermin-helper -f checksum input [...] host_cpu

DESCRIPTION

       supermin-helper reconstructs a bootable kernel and initramfs from a supermin appliance.  First you should
       be familiar with supermin(1).

PARAMETERS

       Specify the input file(s), and -o or --output-* flags indicating where you want the appliance to be
       written.

       Use the -f option to select what type of appliance you want.

       "supermin.img" and "hostfiles.txt" are the input files which describe the supermin appliance.  (You can
       also use a directory name here which is searched for files).

       To write the appliance to a directory, use -o outputdir.  The directory should already exist.  Files
       called "outputdir/kernel", "outputdir/dtb", "outputdir/initrd" and/or "outputdir/appliance" will be
       written.  (Not all files are written, it depends on what kind of appliance you asked for and what
       architecture you are running on)

       To write files with specific names instead, use the --output-kernel, --output-dtb, --output-initrd and/or
       --output-appliance options.

OPTIONS

--help
Display brief command line usage, and exit.

--copy-kernel
Copy the kernel (and device tree, if created) instead of symlinking to the kernel in "/boot".

This is fractionally slower, but is necessary if you want to change the permissions or SELinux label
on the kernel or device tree.

--dtb wildcard
If specified, search for a device tree which is compatible with the selected kernel and the name of
which matches the given wildcard. You can use a wildcard such as "vexpress-*a9*.dtb" which would
match "vexpress-v2p-ca9.dtb".

Notes:

• You may need to quote the wildcard to prevent it from being expanded by your shell.

• If no --dtb option is given, no device tree will be looked for.

• You only need a device tree on architectures such as ARM and PowerPC which use them. On other
architectures, don't use this option.

• If you use this option and no compatible device tree can be found, supermin-helper will exit with
an error.

-f fmt
--format fmt
Select the output format for the appliance. Possible formats are:

cpio
A Linux initramfs. This is the default.

In this case you have to supply output names for the "kernel" and "initrd". The "initrd" is the
appliance.

Note that cpio(1) might not be able to extract this file fully. The format used by the Linux
kernel is not quite a true cpio file.

ext2
An ext2 filesystem.

In this case you have to supply output names for the "kernel", a small "initrd" which is used
just to locate the appliance, and the "appliance" (the ext2 filesystem).

checksum
Output a checksum.

This prints a checksum which only changes when one of the input files changes.

You can use this in order to cache the output of a previous run of this program: computing the
checksum is much quicker than building an appliance, and you only need to invalidate the cache
(and consequently rebuild the appliance) when the checksum changes. Note that the host_cpu and
the UID of the current user are included in the checksum.

--host-cpu cpu
Specify the host CPU (eg. "i686", "x86_64"). This is used as a substring match when searching for
compatible kernels. If not specified, it defaults to the host CPU that supermin-helper was compiled
on.

-k file
--kmods file
If this option is specified, then "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.

-o outputdir
Write the appliance to the named directory. Two or more of the following files will be created (the
exact files created depends on the type of appliance you asked for and the architecture):

"outputdir/kernel"
(ie. A file literally called "kernel" in the directory outputdir that you specified). This is
usually a symlink to the kernel, unless you gave the --copy-kernel option.

"outputdir/dtb"
The device tree. See also the --dtb option.

This is only created on architectures that use device trees, eg. ARM.

This is usually a symlink to the device tree binary file, unless you gave the --copy-kernel
option.

"outputdir/initrd"
The initrd. For -f cpio this also contains the full appliance. For -f ext2 this is just a small
initrd which is sufficient to find and mount the appliance disk.

"outputdir/appliance"
The appliance disk (only for -f ext2).

--output-kernel kernel
Instead of using the literal hard-coded name "kernel", write the kernel to the named path. This
overrides the -o outputdir option (if present).

--output-dtb dtb
Instead of using the literal hard-coded name "dtb", write the device tree to the named path. This
overrides the -o outputdir option (if present).

--output-initrd initrd
Instead of using the literal hard-coded name "initrd", write the initrd to the named path. This
overrides the -o outputdir option (if present).

--output-initrd appliance
Instead of using the literal hard-coded name "appliance", write the initrd to the named path. This
overrides the -o outputdir option (if present).

-u user
--user user
-g group
--group group
Run supermin-helper as an alternate user and/or group. "user" and "group" can be specified as either
a name, which will be resolved using the system name service, or a uid/gid. Use of these options
requires root privileges.

Use of these options is required if running supermin-helper as root with the effective uid/gid set to
non-root. Bash will reset the effective uid/gid to the real uid/gid when invoked. As supermin-
helper uses bash in parts, this will result in the creation of an appliance with a mixture of
ownerships.

-v
--verbose
Enable verbose messages (give multiple times for more verbosity).

-V
--version
Display version number and exit.

COMPRESSED INPUT FILES

       supermin-helper  ≥  4.1.4  supports  gzip-compressed  input  cpio  image  files.   "hostfiles"  cannot be
       compressed.

       Compressing input files saves space, but can make supermin-helper run fractionally slower.

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:

       •   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.

ENVIRONMENT VARIABLES

       SUPERMIN_KERNEL
           If this environment variable is set, then automatic selection of the  kernel  is  bypassed  and  this
           kernel is used.

           The environment variable should point to a kernel file, eg. "/boot/vmlinuz-3.0.x86_64"

           The  corresponding  module path is guessed from the kernel name, but you can override that by setting
           "SUPERMIN_MODULES".

       SUPERMIN_MODULES
           If "SUPERMIN_KERNEL" and "SUPERMIN_MODULES" are both set, then automatic selection of the  kernel  is
           bypassed and the kernel and module path are set to these values.

           The environment variable should point to a module directory, eg. "/lib/modules/3.0.x86_64/"

           This has no effect if "SUPERMIN_KERNEL" is not set.

       SUPERMIN_DTB
           Force the given device tree file to be used.

AUTHORS

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

COPYRIGHT

       (C) Copyright 2009-2013 Red Hat Inc., <http://people.redhat.com/~rjones/supermin>.

       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.

supermin-4.1.5                                     2013-11-12                                 SUPERMIN-HELPER(1)