Setting up Systemd

Note currently this setup is very experimental and a work in progress.

Note as part of this I'm using an initramfs generated from dracut and a custom kernel with some additional options.
I'm not sure if an initramfs is needed for systemd but I'd recommend on reading up on building your own kernel and generating an initramfs first.

Outstanding items

• The custom openrc ebuild for gentoo-on-rpi-64bit needs a patch for gcc10 to allow it to be rebuilt (this is needed below when rebuilding openrc without netifrc to avoid blockages)
• The rpi-64bit-meta ebuilds need patching to not depend on eudev when using systemd
• Certain rpi related init scripts such as from rpi3-ethfix (genpi64-overlay) don't yet support systemd
• xdm is not currently working, currently I'm missing /dev/fb0, this could be related to the init scripts that need patching, or additional modules need to be specified to be loaded on bootup
• need to investigate the use of timedatectl for ntp time

Upsides include

• A little bit quicker on boot / shutdown
• May help with controlling the shutdown process with use with the rpi x735 board (still investigating)

Links

• https://wiki.gentoo.org/wiki/Systemd
• https://github.com/hiroru/gentoo_install#rebooting-into-our-new-gentoo-systemd

Setup

Kernel Rebuild

First I updated the kernel options just to add a couple in based on the Gentoo wiki.
I'm not sure if these are needed but I wanted to make sure everything in the recommended list was included.

Config Option	Menu Location	State
CONFIG_CHECKPOINT_RESTORE	General Setup -> Checkpoint/restore support	Enabled
CONFIG_IPV6	Networking Support -> Networking Options -> The IPv6 Protocol	Changed from module to directly included
CONFIG_EFS_VARS	Firmware Drivers -> EFI (Extensible Firmware Interface) Support -> EFI Variable Support via sysfs	Enabled
CONFIG_CRYPTO_USER_API_HASH	Cryptographic API -> User-space interface for hash algorithms	Enabled
CONFIG_CRYPTO_USER_API_AEAD	Cryptographic API -> User-space interface for AEAD cipher algorithms	Enabled

Depclean / change of use flags

Next we're going to do a depclean, then change some use flags

emerge --ask --depclean
euse -E systemd dbus warmstarts
euse -D consolekit elogind

If you want to use docker then I'd also suggest enabling cgroup-hybrid to prevent any blockages

euse -E cgroup-hybrid

Rebuild openrc

Next we're going to disable netifrc for openrc then re-emerge.
This is to avoid some blockages that might crop up.
Followed by a depclean to clear out netifrc.

echo "sys-apps/openrc -netifrc" > /etc/portage/package.use/temp
emerge --oneshot sys-apps/openrc 
emerge --ask --depclean

This should remove netifrc which is network support for openrc but since we're switching across to systemd we shouldn't need it anyway

Update the world / install systemd

Check for any conflicts

emerge -p -avDN @world

TODO I had to remove the meta for rpi-64bit and docker

emerge -C rpi-64bit-meta
emerge -C app-emulation/docker

emerge the world to install systemd

emerge -avDN @world

Rebuild a couple of packages / update configs

emerge @preserved-rebuild
etc-update

Lets rebuild the initramfs using dracut

dracut --force

Re-emerge network manager

For some reason we need to re-install network manager.
When I first tried the above I ended up with no network so had to do a "dhcpcd eth0" just to get some basic network working just to re-install it

net-misc/networkmanager

Configure systemd

The first line sets up some defaults, the NetworkManager sets up eth0 / wlan0 for networking
sshd is for remote access
xdm is for the xfce desktop

systemctl preset-all --preset-mode=enable-only
systemctl enable NetworkManager
systemctl enable sshd
systemctl enable xdm

Next lets get systemd up and running

reboot

Afterwards try a world update

emerge -up --deep --newuse @world
emerge -up --deep --changed-use @world
revdep-rebuild

Lets make sure the server name is set

hostnamectl set-hostname <server name>
env-update && source /etc/profile

Finishing up

If you needed to uninstall docker during the install then re-install it

emerge app-emulation/docker

This should remove openrc

emerge --depclean
emerge --deselect sys-apps/openrc
emerge --unmerge sys-apps/openrc

systemctl Commands

Starting and stopping services under systemd is a little different

• systemctl daemon-reexec - Can be used after an in place systemd update to avoid a reboot
• systemctl start - Can be used to start a service
• systemctl enable - Can be used to specify a service should be started on bootup
• systemctl list-units --type=service - List all available services