NAME¶
mkinitramfs - low-level tool for generating an initramfs image
SYNOPSIS¶
mkinitramfs [
-c compress] [
-d confdir]
[
-k] -o
outfile [
-r root] [
-v]
[
version]
mkinitramfs [
--supported-host-version= hversion]
mkinitramfs [
--supported-target-version= tversion]
DESCRIPTION¶
The
mkinitramfs script generates an initramfs image. The initramfs is a
compressed cpio archive. The archive can be used on a different box of the
same arch with the corresponding Linux kernel.
mkinitramfs is meant for
advanced usage. On your local box
update-initramfs calls
mkinitramfs with the relevant parameters.
update-initramfs keeps
sha1sum of generated initramfs. It takes care to generate backups and
eventually runs the bootloader.
At boot time, the kernel unpacks that archive into RAM disk, mounts and uses it
as initial root file system. All finding of the root device happens in this
early userspace.
OPTIONS¶
- -c compress
- Override the COMPRESS setting in
initramfs.conf.
- -d confdir
- Set an alternate configuration directory.
- -k
- Keep the temporary directory used to make the image.
- -o outfile
- Write the image to outfile.
- -r root
- Override the ROOT setting in initramfs.conf.
- -v
- Set the verbose mode output.
- version
- Set the kernel version of the initramfs image (defaults to
the running kernel).
- --supported-host-version=hversion
- This option queries if mkinitramfs can create ramdisks on a
running kernel of version hversion.
- --supported-target-version=tversion
- This option queries if mkinitramfs can create ramdisks for
kernel version tversion.
ENVIRONMENT¶
mkinitramfs honours the
TMPDIR environment variable. If set, it
uses subdirectories in the given directory to create its temporary working
directories. Else it uses
/tmp as default value for that purpose. The
given directory should be on a filesystem which allows the execution of files
stored there, i.e. should not be mounted with the
noexec mount option.
FILES¶
- /etc/initramfs-tools/initramfs.conf
- The default configuration file for the script. See
initramfs.conf(5) for a description of the available configuration
parameter.
- /etc/initramfs-tools/modules
- Specified modules will be put in the generated image and
loaded when the system boots. The format - one per line - is identical to
that of /etc/modules, which is described in modules(5).
- /etc/initramfs-tools/conf.d
- The conf.d directory allows one to hardcode bootargs at
initramfs build time via config snippets. This allows one to set ROOT or
RESUME. This is especially useful for bootloaders, which do not pass an
root bootarg.
- /etc/initramfs-tools/DSDT.aml
- If this file exists, it will be appended to the initramfs
in a way that causes it to be loaded by ACPI.
EXAMPLES¶
Create an initramfs for current running kernel:
mkinitramfs -o ~/tmp/initramfs-$(uname -r)
Create an initramfs for specific kernel and keep builddirs:
mkinitramfs -k -o ~/tmp/initramfs-2.6.21-686 2.6.21-686
Debug initramfs creation (check out written logfile)
sh -x mkinitramfs -o ~/tmp/initramfs-$(uname -r) 2> ~/tmp/log
AUTHOR¶
The initramfs-tools are written by Maximilian Attems <maks@debian.org>,
Jeff Bailey <jbailey@raspberryginger.com> and numerous others.
SEE ALSO¶
initramfs.conf(5),
initramfs-tools(8),
update-initramfs(8).
