.\" Man page for mkinitrd
.\"
.\" Copyright (C) 2001-2003 Herbert Xu <herbert@debian.org>
.\"
.\" 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
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.\" 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.
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.\" Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
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.\" $Id: mkinitrd.8,v 1.25 2004/04/08 11:27:00 herbert Exp $
.TH MKINITRD 8 "$Date: 2004/04/08 11:27:00 $" "Initrd Tools"

.SH NAME
mkinitrd \- make an initrd image

.SH SYNOPSIS

.B mkinitrd
.RB [ \-k ]
.RB [ \-d
.IR confdir ]
.RB [ \-m
.IR command ]
.B \-o
.I outfile
.RB [ \-r
.IR root ]
.RI [ version ]

.B mkinitrd
.RB [ \-\-supported-host-version=
.IR hversion ]
.RB [ \-\-supported-target-version=
.IR tversion ] 

.SH DESCRIPTION

The
.B mkinitrd
script constructs a directory structure that can serve as an
.B initrd
root file system.  It then generates an image containing that directory
structure using
.BR mkcramfs (8),
which can be loaded using the
.B initrd
mechanism.  The kernel modules for the specified kernel version will be
placed in the directory structure.
If
.I version
is omitted, it defaults to the version of the kernel that is currently running.

.PP

The second syntax returns 0 if mkinitrd can create a ramdisk running on a kernel
of the given host version (
.IR hversion
) and for a kernel of the given target version (
.IR tversions
), and 2 otherwise.

.PP

The directory structure can be customised by placing scripts into
.IR confdir/scripts .
They will be run using
.BR run-parts (8)
just before the directory is fed to
.BR mkcramfs (8).
If there are scripts in
.IR /usr/share/initrd-tools/scripts ,
they will be run prior to the scripts in
.IR confdir .

.PP

You can also specify modules to load by putting them in
.IR confdir/modules ,
whose format is identical to that of
.IR /etc/modules ,
which is described in
.BR modules(5) .

When the system boots using an
.B initrd
image created by
.BR mkinitrd (8),
the
.B linuxrc
will wait for an amount of time which is configured through
.BR mkinitrd.conf (5),
during which it may be interrupted by pressing
.BR ENTER .
After that, the modules specified in
.I confdir/modules
(and possibly others if
.B ROOT
is not null) will be loaded, followed by any actions generated when
.B ROOT
is not null.  Finally any scripts or executables in
.I /scripts
will be run in alphabetical order.

If the directory
.I /lib/modules/version/initrd
exists, the modules in it will be included on the
.B initrd
image.  They will be loaded at boot time.

.SH OPTIONS

.TP
\fB\-d \fIconfdir
By default
.B mkinitrd
looks for its configuration files in
.IR /etc/mkinitrd .
Use this option to override that.

.TP
.B \-k
Do not delete the temporary working directory that
.B mkinitrd
uses.  This is useful for debugging.

.TP
\fB\-m \fIcommand
This option overrides the setting of
.B MKIMAGE
in
.IR mkinitrd.conf .

.TP
\fB\-o \fIoutfile
This option causes
.B mkinitrd
to write the image to
.IR outfile .

.TP
\fB\-r \fIroot
This option overrides the setting of
.B ROOT
in
.IR mkinitrd.conf .

.TP
\fB\-\-supported-host-version=\fIhversion
This option queries if mkinitrd can create ramdisks on a running kernel of version
.IR hversion .

.TP
\fB\-\-supported-target-version=\fItversion
This option queries if mkinitrd can create ramdisks for kernel version
.IR tversion .

.SH FILES

.TP
.I /etc/mkinitrd/exe
This file contains full paths to shared executables that should be included
in the
.B initrd
image.
.B mkinitrd
will include them as well as any shared libraries that they are linked with.

.TP
.I /etc/mkinitrd/files
This file contains full paths to files that should be included in the
.B initrd
image.

.TP
.I /etc/mkinitrd/mkinitrd.conf
The default configuration file for the script.

.TP
.I /etc/mkinitrd/modules
All modules specified in this file will be loaded when the system boots
using the generated image.  However, they are not automatically included
on the image.  You will either have to use the appropriate
.B MODULES
setting, or copy them in using a script in
.IR /etc/mkinitrd/scripts .

.TP
.I /etc/mkinitrd/scripts
Scripts in this directory matching the
.BR run-parts (8)
naming convention are run just before the image is generated from.
.BR INITRDDIR ,
.B MODULEDIR
and
.B VERSION
are available to the scripts.  They contain the path to the
.B initrd
directory structure under construction, the value of
.IR /lib/modules/version ,
and the value of
.I version
respectively.

.TP
.I /etc/mkinitrd/DSDT
If this file exists, it will be appended to the initrd in a way that causes
it to be loaded by ACPI.

.SH NOTES

By default
.B mkinitrd
will generate a
.B CRAMFS
image.
You can generate an
.B initrd
image of another type by changing the
.B MKIMAGE
setting in
.IR mkinitrd.conf .

.PP

If both
.BR mdadm (8)
and
.B raidtools2
are installed, the former is preferred.  At the moment,
.B mkinitrd
uses the
.B -D
option of
.BR mdadm (8)
to discover the constituent devices.  This means that only devices that are
part of the array at the time that
.B mkinitrd
is run will be used later on.  This problem does not exist when
.B raidtools2
is used.

.PP

Because
.B lvm10
and
.B lvm2
cannot coexist currently, we do not support generating an
.B initrd
image for
.B lvm10
while the system is running
.BR lvm2 .
The converse is supported.

.PP

Shell scripts may be placed in
.I /usr/share/initrd-tools/probe.d
to add new methods for probing root devices.  These scripts will be
sourced when
.B mkinitrd
runs.  They should define a shell function that assigns the value
.I 1
to the variable
.B ok
if and only if it is able to handle the device given to it.  The
function will be called with the major and minor numbers of the
device in decimal form.  The script should call the function
.B register_probe
with the name of that function.  These scripts must defer any
real work to scripts in
.I /usr/share/initrd-tools/scripts
so that they do not interfere with
.B mkinitrd
itself.

.SH "SEE ALSO"

.BR mkcramfs (8),
.BR mkinitrd.conf (5),
.BR run-parts (8)

.SH AUTHOR
Herbert Xu <herbert@debian.org>