Run Linux entirely from RAM! This project creates and enables a custom mkinitcpio hook that completely loads the root (and /boot) filesystem into RAM during the initramfs boot stage.

Arch Linux

This package is designed specifically to work with the Arch Linux boot process. I suspect these scripts may work with slight modifications on other distributions as well, however this is currently untested.

sudo

The ramroot script can be run as root or as a normal user. If executed as a normal user, sudo will be called when necessary to modify or create initcpio files, and the user will be prompted for his or her sudo password.

This package is available in the AUR for easy installation, however the ramroot script can also be run directly from a local git clone of this repository.

ramroot <action> [options]

Ramroot can enable and disable the pre-userspace loading of the root (and /boot, if it exists) filesystem to RAM during system boot.

When ramroot is enabled, during the initial phase of boot the amount of detected RAM on the computer along with the size the root filesystem to be copied is shown on the screen. If there is at least 500MB more RAM than the size of the filesystem, the user will be prompted to load the root filesystem to RAM. (Confirmation prompt defaults to yes with a 15 second timeout.)

The size of the zram partition created is determined by taking the size of the root filesystem plus half of the extra available RAM (to a maximum of 6GB).

Action performed by ramroot; one must be specified.

disable

Remove ramroot from /etc/mkinitcpio.conf HOOKS. Remove ext4 and zram from /etc/mkinitcpio.conf MODULES. Rebuild linux cpio boot image.

enable

Rebuild build and runtime hooks in /usr/lib/initcpio. Add ramroot to /etc/mkinitcpio.conf HOOKS. Add ext4 and zram to /etc/mkinitcpio.conf MODULES. Rebuild linux cpio boot image.

remove

Disable ramroot. Remove build and runtime hooks from /usr/lib/initcpio.

status

Print ramroot status to screen. Return exit status 2 if not enabled.

All are optional (although --root may be required as noted below).

-b, --boot <UUID>

Specify /boot partition UUID to use when building hooks.

-D, --dryrun

Execute action without making any changes. Useful for debugging or viewing changes in ~/.cache/ramroot before enabling.

-H, --help

Display help text and exit.

-K, --keep

Keep copies of new build and runtime hooks in ~/.cache/ramroot.

-N, --no

Change startup prompt default to not load filesystem to RAM.

-r, --root <UUID>

Specify root partition UUID to use when building hooks; required if unable to detect UUID via lsblk or /etc/fstab.

-t, --timeout <SECONDS>

Set RAM boot prompt timeout (default=15).

The filesystem transfer to RAM can take several minutes. As soon as the boot process is complete, the boot media can be safely removed.

Remember that all changes to files in RAM are completely lost once the computer is reboot. To update the system and edit files, boot the device without transferring the filesystem to RAM.

Keep a clean and trimmed down system to maintain faster RAM sync times. Arch Linux stores downloaded packages in /var/cache/pacman/pkg/. After every update, if no problems occur, consider removing old packages. Consider installer fewer packages if you indend on loading to RAM often.

Also, keep in mind that higher quality (more expensive) USB flash drives often exhibit a dramatic improvement in RAM sync times.

• use getopts to allow grouping command line options together
• --rsync option (maybe use rsync automatically if installed)
• added security
  • test compatibility with full disk encryption
  • option to require removal of boot media before starting userspace
  • option to fail boot unless loaded to RAM (requires a chroot to make any changes)
• flush action to sync the RAM filesystem back to the initial boot device
• add support for other partitions users may have
• use config file?
  • great for setting a bunch of options
  • probably shouldn't read and parse config file during pre-userspace boot for security/basic functionality reasons; hooks should be rebuilt and linux boot image regenerated with every config change
• test on other distros

This project was motivated greatly in part by the liveroot package and by several inquisitive forum posts.