OVERVIEW

mkinitramfs generates bootable initramfs images for Linux systems.

It is a fork of illiliti's tinyramfs at commit 8abfcc9 (Fri May 21 2021), with the following changes:

• Bash completion support
• GNU-style options and usage output
• Command-line parsing via GNU getopt(1)
• Use of local to prevent namespace pollution
• Support for rootdelay kernel parameter
• Experimental smdev hook
• luks hook: prompts for password if header/keyfile is missing
• extrafiles directive: copy arbitrary files into image
• resume hook: supports hibernation resume from swap partitions or files
• Split keymap hook into loadkmap and loadkeys (supports BusyBox and kmod)

See the git log for full history.

The original sources can be downloaded from:

1. https://github.com/illiliti/tinyramfs
2. https://github.com/illiliti/tinyramfs/archive/8abfcc9/tinyramfs-8abfcc9.zip

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FEATURES

The following advantages can be distinguished:

• No bashisms, only POSIX sh(1p) (with local exception)
• Portable, no distribution-specific
• Simple configuration
• Build-time and init-time hooks
• LUKS (detached header, key, password), LVM
• smdev, mdev, mdevd, eudev, systemd-udevd

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REQUIREMENTS

Kernel Configuration

The kernel must be built with:

General setup
  [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
      CONFIG_BLK_DEV_INITRD=y

Device Drivers
  Generic Driver Options
    [*] Maintain a devtmpfs filesystem to mount at /dev
        CONFIG_DEVTMPFS=y

For encrypted root support, enable:

Device Drivers --->
  Multiple devices driver support (RAID and LVM) --->
    [*] Device mapper support
    [*] Crypt target support

Cryptographic API --->
  <*> XTS support
  <*> SHA224 and SHA256 digest algorithm
  <*> AES cipher algorithms
  <*> AES cipher algorithms (x86_64)
  <*> User-space interface for hash algorithms
  <*> User-space interface for symmetric key cipher algorithms

Build-time

• POSIX sh(1p), make(1p), and "mandatory utilities"
• scdoc(1) to generate manual pages

Runtime

• Any POSIX-compatible shell with local support (e.g., dash(1), Busybox ash(1))
• GNU getopt(1), switch_root(8), mount(8), cpio(1)

Optional runtime dependencies:

• ldd(1) for copying binary dependencies
• strip(1p) for reducing image size by stripping binaries
• blkid(8) for UUID, LABEL, PARTUUID support
• smdev OR mdev OR mdevd OR eudev OR systemd-udevd or CONFIG_UEVENT_HELPER
• lvm(8) for LVM support
• cryptsetup(8) for LUKS support
• Busybox loadkmap or kbd loadkeys(8) for keymap support
• kmod(8) OR Busybox modutils+patch for non-monolithic kernels

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INSTALLATION

To install:

# as root
make install

Configuration parameters are defined in config.mk.

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DOCUMENTATION

Basic usage

Configure /etc/mkinitramfs/config conform your needs (see mkinitramfs.config(5)).

Generate the initramfs:

# as root
mkinitramfs -o "/boot/initramfs-$(uname -r).img"

Update your bootloader configuration (example for GRUB2):

# as root
grub-mkconfig -o /boot/grub/grub.cfg

Reboot.

Online documentation

Provided in /man and installed under the system manual hierarchy.

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CREDITS

Original developers:

• illiliti https://github.com/illiliti
• E5ten https://github.com/E5ten
• dylanaraps https://github.com/dylanaraps

Support the original author:

• illiliti / (BTC) 1BwrcsgtWZeLVvNeEQSg4A28a3yrGN3FpK
• https://patreon.com/illiliti

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LICENSE

mkinitramfs is licensed under the GNU General Public License v3 or later.

See COPYING for license terms and COPYRIGHT for notices.