mkinitrd - create initrd disk image


mkinitrd [options] [root_dir]


mkinitrd creates initial ramdisk images for booting Linux. The "/init" script in the compressed cpio archive loads all driver modules, creates all device nodes currently known by the kernel, initializes vital subsystems (e.g. networking when doing nfs), does a filesystem check on the root filesystem and finally passes control to /sbin/init. udev is used to create the device nodes in a tmpfs mounted /dev directory. This directory is moved over to the final root filesystem, essentially hiding the on-disk content below /dev on the root filesystem.

A few options can be specified via the kernel command line to modify some hardcoded values in the "/init" script. They are read from /proc/cmdline.

While in the old days the Linux kernel was responsible for mounting the rootfilesystem and running /sbin/init, all the work is now done by the "/init" script.



Shows help output and exits.


Prints the version and exits. We use -R (release) because -v (verbose) and -V (vendor scripts) are already taken.

-k kernel_list

List of kernel images for which initrd files are created (relative to boot_dir), defaults to vmlinux on ppc/ppc64, image on s390/s390x and vmlinuz for everything else.

-i initrd_list

List of file names (relative to boot_dir) for the initrd; positions have to match the kernel_list, defaults to initrd.

-m module_list

Modules to include in initrd, defaults to INITRD_MODULES variable in /etc/sysconfig/kernel.

-f feature_list

Features to be enabled for the initrd. In general mkinitrd configures the initrd for the root device it is started from. With this option additional feature can be enabled.

-b bootdir

Boot directory, defaults to /boot, where the initrd is created.

-d root_device

Root device, defaults to the device from which the root_dir is mounted; overwrites the rootdev enviroment variable if set

-s size

Add splash animation and bootscreen to initrd.

-D interface

Run dhcp on the specified interface (for example "eth0").

It\(cqs also possible to specify "default" here if the default interface should be used. If there\(cqs a file /etc/install.inf (which is from the installation system), then the interface that was used for installation is used as default interface. Otherwise, if NFS root is used and one of the network configuration files in /etc/sysconfig/network contain the option STARTMODE=nfsroot, than this interface is used as default. Finally, the interface which is used for the default route (in the output of /sbin/route is used as default interface in the initrd.

-I interface

Configure the specified interface statically.

-a acpi_dsdt

Attach compiled ACPI DSDT (Differentiated System Description Table) to initrd. This replaces the DSDT of the BIOS. Defaults to the ACPI_DSDT variable in /etc/sysconfig/kernel.


Use static binaries where possible. (currently unavailable)


Include modules for all IDE devices on the PCI bus.

-V script

Vendor specific script to run in linuxrc.

-M map file to use.

-j device

External journal device to use for the root filesystem.

-l directory

Directory to use for mkinitrd files instead of /lib/mkinitrd.


Don\(cqt run the update-bootloader(8) script after the initrd(s) have been created. This is useful if you call mkinitrd(8) not for the running system but for example in a spec file to pre-generate an initrd or to generate a special kdump initrd (which mkdumprd(8) does).


Create a so called "monster initrd" which includes all available features and modules.


Do not include all libata modules by default.


Verbose mode. Prints more information to standard error. By default the information that would be printed in verbose mode is also appended to the log file /var/log/YaST2/mkinitrd.log, so it\(cqs not necessary to re-run mkinitrd with the -v option to create bug reports.


Disable logging to /var/log/YaST2/mkinitrd.log. This is useful for testing if you don\(cqt want to clutter the system log.


The directory the root partition is mounted to defaults to "/".


mkinitrd implements a set of additional kernel command-line parameters which are interpreted by the generated init script. In addition to the standard kernel parameters the following parameters are supported:


Enabling command tracing of the init script


Execute a shell after the linuxrc has finished and before the normal system is booted. Useful for debugging.


Do not check for a resume device

sysrq=yes | sysrq=1-9

Enable sysrq. If a numeric value is specified, the log level of the console will be set to that value.


Resume from device device.


Use device device as external journal device. This is only valid for reiser and xfs filesystems.


Mount md RAID with uuid UUID as the root filesystem.


[iSCSI] IP Address of the iSCSI Target

InitiatorName=iqn. [iSCSI] Use iqn as the iSCIS initiatorname.


Use ipspec to configure the network interface. Format of the ipspec is client:server:gateway:netmask:hostname:device:proto. client, server, gateway, netmask are in the standard dotted-decimal IP notation. proto is currently ignored.


Set the timeout for root device detection to secs seconds. Default is 10.


Normally mkinitrd detects all required features automatically, based upon the current root, resume, dump and journal device. If additional features should be enabled, the -f option can be specified. Of course you can write your own features as well. Just take a look at /lib/mkinitrd.

Currently, the following features can be selected (if a feature is available depends on the installed packages):


Include support for block devices (SCSI and IDE)


Replace and add all tools known as safe with the busybox versions


Include support for dasd storage devices (s390)


Include support for Software-Raid over device mapper (known as Fake-Raid)


Include support for device mapper in general


Add support for EVMS


Include firewire storage


Include iSCSI support


Include support for kpartx partitioning. Always use this if you have device mapper devices.


Include encryption support using luks


Include support for LVM2


Include support for Software RAID (md)


Include support for multipathing


Include support for debugging using netconsole


Include networking support


Include support for nfs(-root)


Include resume support using the kernel resume code


Include resume support using the userspace program


Include USB-support (keyboard and storage)


Include vendor script support


Include support for zfcp storage devices (s390)


To configure an initrd for an NFS client, specify these options to add nfs and network driver support into the initrd:

mkinitrd -f nfs -D eth0

This will add the required kernel modules and a dhcp client to the initrd, which will try to get an IP address via eth0. Boot the NFS client with these additional command line options to mount the server: nfsroot=

mkinitrd -f nfs -I eth0

This will add the required kernel modules to the initrd, a static IP address must be specified on the kernel cmdline. Boot the NFS client with the nfsroot parameter as specified above to mount the server and the additional parameter ip= to configure the network interface. See the ip= description above for details about the ip= option.


Due to the new autodetection in mkinitrd it should suffice if the /-entry in /etc/fstab is an nfs target. The network device which will be used should have STARTMODE set to nfsroot.


What should you do if the initrd is broken and you want to fix it using a chroot? I assume /mnt is your target root and /boot is mounted inside.

  1. mount --bind /dev /mnt/dev
  2. chroot /mnt
  3. mount /proc
  4. mount /sys
  5. mkinitrd



The log file of this program. Always attach that log file in Bugzilla if something goes wrong. It\(cqs also included in the usual YaST logs that are created with save_y2logs(8).


You can specify the root device via the environment variable rootdev (e.g. "rootdev=/dev/hda mkinitrd").

Also, the temporary directory which is used to build the initrd can be specified using the TMPDIR environment. If not set, /dev/shm is used as root (when it\(cqs writable) and /tmp otherwise.


Steffen Winterfeldt <>, Susanne Oberhauser <>, Andreas Gruenbacher <>, Hannes Reinecke <>, Alexander Graf <>, Bernhard Walle <>


mkinitrd(8), mkinitrd(5)

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