Plugins

As of now plugins for the following bootloaders exist:

• FreeBSD’s loader - freebsdloader
• systemdboot - systemdboot

In order to integrate with a bootloader, an extra flag ‘-b/--bootloader’ must be used to specify a bootloader plugin. The plugin will make the necessary changes to boot from the new Boot Environment.

If you expect you will always be using a certain bootloader, you can set the org.zedenv:bootloader property on your boot environments, and the bootloader plugin will be used without you having to specify.

$ zedenv set org.zedenv:bootloader=<bootloader plugin>

Plugins available for your system can be listed with zedenv --plugins.

freebsdloader

The freebsdloader plugin is quite simple. During activation, it will respect /etc/rc.d/zfsbe if it exists, and set, all datasets to canmount=noauto, otherwise the datasets will be set canmount=on.

It will also change the root dataset to mount from in /boot/loader.conf, and /boot/loader.conf.local.

The current /boot/zfs/zpool.cache will also be copied into the newly activated boot environment.

systemdboot

Multiple kernels can be managed with this plugin and systemd-boot, but it will require changing the mountpoint of the esp (EFI System Partition).

Problem With Regular Mountpoint

Usually the $esp would get mounted at /boot or /boot/efi. The kernels would sit in the root of the $esp, and the configs for systemdboot in $esp/loader/.

$esp
.
├── initramfs-linux-fallback.img
├── initramfs-linux.img
├── intel-ucode.img
├── vmlinuz-linux
│
└── loader/
    ├── entries/
    │   └── arch.conf
    └── loader.conf

The configs would then reference kernels in the root directory.

title           Arch Linux
linux           vmlinuz-linux
initrd          intel-ucode.img
initrd          initramfs-linux.img
options         zfs=bootfs rw

The problem with this method, is multiple kernels cannot be kept at the same time. Therefore this hierarchy is not conducive to boot environments.

Alternate Mountpoint

First, remount the $esp to a new location, the default is /mnt/efi.

If you would like to explicitly specify the mountpoint used, you can set the org.zedenv.systemdboot:esp property on your current boot environment, and the plugin will use the specified location:

zedenv set org.zedenv.systemdboot:esp='/mnt/efi'

Don’t forget to change the mount point in /etc/fstab.

UUID=9F8A-F566            /mnt/efi  vfat    rw,defaults,errors=remount-ro  0 2

Now, make a subdirectory $esp/env, kernels will be kept in a subdirectory of this location.

The bootloader configuration can now use a different path for each boot environment.

So the ‘default’ boot environment config, located at $esp/loader/entries/zedenv-default.conf, would look something like:

title           Arch Linux
linux           /env/zedenv-default/vmlinuz-linux
initrd          /env/zedenv-default/intel-ucode.img
initrd          /env/zedenv-default/initramfs-linux.img
options         zfs=zpool/ROOT/default rw

To make the system happy when it looks for kernels at /boot, this directory should be bindmounted to /boot.

Bindmount /mnt/efi/env/zedenv-default to /boot in /etc/fstab.

/mnt/efi/env/zedenv-default   /boot     none    rw,defaults,errors=remount-ro,bind    0 0

If this directory is not here, the kernels will not be updated when the system rebuilds the kernel.

Once our system is set up in the proper configuration, zedenv will update the bootloader, and fstab - if requested - when a new boot environment is activated.

It will also update the configuration described above, asking you if the modifications that made are correct. You will have a chance to inspect and change them if they are not.

If you are confident and the changes it is making, and do not wish to inspect them, adding the --noconfirm/-y flag will run the command without asking for confirmation.