Initramfs zfs boot

Overview

Both Debian and Ubuntu fail to boot when there is an arbitrarily more complex zpool than a single vdev that contains the bootfs.

Notes on Boot Process

• The linux kernel is initially bootstrapped.
• The compiled-in initramfs is mounted and executed.
  • It mounts the external initramfs; Deletes everything under its own initramfs; Executes the external initramfs /init

(External) initramfs init

• Create
  • /dev
  • /root
  • /sys
  • /proc
  • /tmp
  • /var/lock
• Mount
  • /sys
  • /proc
  • /dev
  • /dev/pts
  • /run
• Create
  • /run/initramfs
• Setup bash exports
• Setup hostname
• Source
  • /conf/initramfs.conf
  • /conf/conf.d/*
  • /scripts/functions

• Parse command line options
  • init root rootflags rootfstype rootdelay resumedelay loop loopflags loopfstype crytopts nfsroot netboot ip ip6 boot ubi.mtd resume resume_offset noresume drop_capabilities panic quiet ro rw debug break blacklist netconsole BOOTIF hwaddr fastboot forcefsck fsckfix fsckmode fsck.repair recovery

• Default
  • BOOT=local
  • noresume

• maybe_break top
  • export BOOT
  • run_scripts /scripts/init-top
• maybe_break modules
  • load_modules
• maybe_break premount
  • run_scripts /scripts/init-premount
• maybe_break mount
• /scripts/local
• /scripts/nfs
• /scripts/BOOT
• parse_numeric ROOT
• maybe_break mountroot
• mount_top
• mount_premount
• mountroot

• Mount
  • /usr

• mount_bottom
• nfs_bottom
• local_bottom
• maybe_break bottom
  • run_scripts /scripts/init-bottom