Systemd

Switching init systems is a non trivial operation that has implications for how the system is configured, and sometimes for what software can be installed or not. Generally, an init system will be chosen at installation time (i.e. by downloading either a systemd or an openrc stage3 tarball), and only changed if necessary. In true Gentoo style, in addition to systemd and OpenRC, several init systems are supported.

If sys-apps/sysvinit is still blocking sys-apps/systemd, make sure it and sys-apps/openrc are not contained in the world file:

If the @system set provides sys-fs/eudev, virtual/udev and virtual/libudev may be preventing systemd. To make portage resolve the problem, after setting the USE flag, try to reinstall the virtuals:

Yaboot is a boot loader for PowerPC-based hardware running Linux, particularly New World ROM Macintosh systems.

The init=/lib/systemd/systemd argument should be added directly after the kernel command-line. An example from yaboot.conf:

For the changes to take effect, the ybin command must be run each time the yaboot.conf file is modified.

systemd has the ability to update in-place on a running system (no reboot necessary). After an upgrade to systemd has emerged, run the following command:

After installing systemd, run the following:

After doing any of the above, update the environment so the changes will take effect:

Automatic mounting of partitions at boot

Systemd is capable of automatically mounting various partitions to standardized location via systemd-gpt-auto-generator. This makes it possible to boot and automatically mount essential partitions without an fstab and without a root= paramter on the kernel command line. To use this capability, first systemd must be included in the initramfs, this is the case by default for initramfs images generated with Dracut on systems with systemd installed. And second, each partition must have the correct Partition Type GUID. A list of the most important GUIDs can be found in the systemd-gpt-auto-generator manual, the full list can be found on wikipedia.

To list the current Partition Type GUID of your partitions:

systemd-gpt-auto-generator can auto-mount partitions at the following locations, note that the correct GUID depends on the systems CPU architecture:

• / SD_GPT_ROOT_....
• /boot/ SD_GPT_ESP if no /efi/ and no XBOOTLDR partition, otherwise SD_GPT_XBOOTLDR
• /efi/ SD_GPT_ESP if /efi/ is present on the root, if not then ESP is at /boot/
• /home/ SD_GPT_HOME
• /srv/ SD_GPT_SRV
• /usr/ SD_GPT_USR_....
• /var/ SD_GPT_VAR
• /var/tmp/ SD_GPT_TMP
• Swap SD_GPT_SWAP

Below is an example of the most basic partition layout consisting of one EFI System Partition and one x86-64 root partition.

The PARTTYPE for an EFI System Partition is c12a7328-f81f-11d2-ba4b-00a0c93ec93b, it will be mounted at either /efi/ or /boot/ depending on which of these mount points is available and on if there is also an Extended Boot Loader Partition (PARTTYPE=bc13c2ff-59e6-4262-a352-b275fd6f7172) present on this disk. The PARTTYPE for an x86-64 root parition is 4f68bce3-e8cd-4db1-96e7-fbcaf984b709.

If the Partition Type GUID is not correct it can be changed without data loss using a partitioning tool such as fdisk. Note that the system must be offline to change the patition types! A system rescue image, or secondary operating system, must be used to complete the following steps.

Open the disk with the to be changed partition types in fdisk, in this exameple /dev/nvme1n1 is used:

List the current partition layout with the p command:

Change the Partition Type GUID of any partition with the t command, followed by the number of the partition to be changed, and finally the alias for the desired partition type:

Repeat the above steps for any additional partitions of which the Partition Type GUID should be changed. Once completed, save the changes with the w command:

systemd is compatible with various network management tools.

See the systemd/systemd-networkd article for details on setting up a wired network on systemd systems.

systemd-resolved

See the systemd/systemd-resolved article for details on setting up address name resolution (DNS) on systemd systems.

For more details see the dedicated article.

If desired, the logging service be configured to pass log messages to external logging utilities such as sysklog or syslog-ng. See man journald.conf to learn how to configure the systemd-journald service to suit situational needs.

systemd's integrated logging service writes log messages in a secure, binary format. The logs are read by using the journalctl command, which is a separate executable from the systemd-journald logging service.

| journalctl without options || Show all log entries, starting with earliest. |-

| -b, --boot || Show all log entries from the current boot. |-

| -r, --reverse || Show the newest log entries first (reverse chronological order). |-

| -f, --follow || Show the last few entries and display new log entries as they're being produced. This is similar to running tail -f in text logging utilities. |-

| -p, --priority= || Specify (minimum) priority to display messages, with a choice from: "emerg" (0), "alert" (1), "crit" (2), "err" (3), "warning" (4), "notice" (5), "info" (6), "debug" (7). |-

| -S, --since=, -U, --until= || Restrict entries by time. Accepts the format "YYYY-MM-DD hh:mm:ss" or the strings "yesterday", "today" and "tomorrow". |-

| -n, --lines= || Restrict to a number of entries. |-

| -k, --dmesg || Restrict to kernel messages. |-

| -u, --unit= || Restrict to a certain systemd unit. |-

| --system || View system service and kernel logs. By default, this is only possible as the root user. See man journalctl for how to grant standard users the ability to read the system journal. |-

|}

Most services are disabled when systemd is first installed. A "preset" file is provided, and may be used to enable a reasonable set of default services.

| .service | Plain service files (e.g. ones just running a daemon directly). |-

| .socket | Socket listeners (much like inetd). |-

| .path | Filesystem triggers for services (running services when files change, etc.). |-

|}

Services implementing ExecReload= can be commanded to reload their configuration without restarting itself:

Both the drop-in directory and config file can be created using the systemctl edit utility or manually.

The editing utility can be invoked as:

! scope="col" | Gentoo package ! scope="col" | OpenRC service ! scope="col" | systemd unit ! scope="col" | Notes |-

! scope="row" rowspan="28" | sys-apps/openrc | bootmisc || systemd-tmpfiles-setup.service || always enabled, uses tmpfiles.d |-

| consolefont || systemd-vconsole-setup.service || always enabled, uses vconsole.conf |-

| devfs || || |-

| dmesg || || |-

| fsck || fsck*.service || pulled in implicitly by mounts |-

| functions.sh || See note || bug #373219 |-

| hostname || (builtin) || /etc/hostname |-

| hwclock || See note || always enabled as part of systemd (i.e. it is baked in and it is not a unit) |-

| keymaps || systemd-vconsole-setup.service || always enabled, uses vconsole.conf |-

| killprocs || || |-

| local || || |-

| localmount || local-fs.target || actual units are created implicitly from /etc/fstab |-

| modules || systemd-modules-load.service || always enabled, uses /etc/modules-load.d/*.conf |-

| mount-ro || || |-

| mtab || || |-

| netmount || remote-fs.target || |-

| numlock || || |-

| procfs || (builtin) || |-

| root || remount-rootfs.service || |-

| savecache || n/a || OpenRC internals |-

| staticroute || || |-

| swap || swap.target || actual units are created implicitly from /etc/fstab |-

| swclock || || |-

| sysctl || systemd-sysctl.service || sysctl.conf and sysctl.d/ |-

| sysfs || (builtin) || |-

| termencoding || systemd-vconsole-setup.service || always enabled, uses vconsole.conf |-

| scope="row" rowspan="2" | urandom | systemd-random-seed-load.service || |-

| systemd-random-seed-save.service || |-

! scope="row" | app-admin/rsyslog | rsyslog || rsyslog.service || |-

! scope="row" | app-admin/syslog-ng | syslog-ng || syslog-ng.service || |-

! scope="row" rowspan="2" | media-sound/alsa-utils | scope="row" rowspan="2" | alsasound | alsa-store.service || (enabled by default) |-

| alsa-restore.socket || (enabled by default) |-

! scope="row" | net-misc/dhcpcd | dhcpcd || dhcpcd.service || |-

! scope="row" rowspan="5" | net-misc/netifrc | scope="row" rowspan="5" | net.* | net@.service || systemd wrapper for net.* scripts (comes with net-misc/netifrc) |-

| netctl@.service || net-misc/netctl is originally an Arch Linux tool. |-

| NetworkManager.service || For <networkmanager-0.9.8.4 : enable NetworkManager-dispatcher.service for dispatcher.d scripts to work.
Enable NetworkManager-wait-online.service to detect that the system has a working internet connection.
Disable all other managers (e.g., wicd, dhcpcd) and wpa_supplicant. |-

| dhcpcd.service || Provided by net-misc/dhcpcd |-

| systemd.networkd.service || Part of systemd |-

! scope="row" | net-misc/openntpd | ntpd || ntpd.service || |-

! scope="row" rowspan="2" | net-misc/openssh | scope="row" rowspan="2" | sshd | sshd.service || runs sshd as a daemon |-

| sshd.socket || runs sshd on a inetd-like basis (for each incoming connection) |-

! scope="row" rowspan="2" | net-wireless/wpa_supplicant | scope="row" rowspan="2" | wpa-supplicant | wpa_supplicant.service || D-Bus controlled daemon (e.g. for NetworkManager) |-

| wpa_supplicant@.service || interface-specific wpa_supplicant (used like wpa_supplicant@wlan0.service) |-

! scope="row" rowspan="3" | net-print/cups | scope="row" rowspan="3" | cupsd | cups.service || classic on-boot start up service |-

| cups.socket | scope="row" rowspan="2" | socket and path activation (cups only started on-demand) |-

| cups.path |-

! scope="row" | net-wireless/bluez | bluetooth || bluetooth.service || |-

! scope="row" rowspan="2" | sys-apps/dbus | scope="row" rowspan="2" | dbus | dbus.service || |-

| dbus.socket || |-

! scope="row" | sys-apps/irqbalance | irqbalance || irqbalance.service || supports daemon mode only |-

! scope="row" | sys-apps/microcode-ctl | microcode_ctl || || Configure microcode as a module to let it load the microcode itself. Go to "Processor type and features" -> "CPU microcode loading support" and remember to add the right option based on the system having an Intel or AMD processor. |-

! scope="row" rowspan="4" | sys-fs/udev | udev || udev.service || |-

| udev-mount || (builtin) || /dev is mounted as tmpfs |-

| udev-postmount || udev-trigger.service || |-

| || udev-settle.service || |-

! scope="row" | sys-power/acpid | acpid || acpid.service || Most of its functionality is done by systemd itself, so consider disabling this |-

! scope="row" | x11-apps/xdm | (xdm) || xdm.service || OpenRC uses common xdm init.d installed by x11-base/xorg-server. With systemd the corresponding unit file for each DM (gdm.service, kdm.service...) needs to be enabled. |-

! scope="row" rowspan="2" | net-firewall/iptables | scope="row" rowspan="2" | iptables | iptables-store.service || |-

| iptables-restore.service || |-

|}

User services

It is possible to manage services as a per-user systemd instance. This allows users to setup their own services or timers.

User units can be located at multiple places. Users are allowed to place them to $XDG_CONFIG_HOME/systemd/user/. Installed packages place them to /usr/lib/systemd/user/.

User services use --user systemctl option. For example to start a mpd user service:

These unit files can be created either manually or using the systemctl edit utility:

When creating the unit files manually, the files are to be placed in the ~/.config/systemd/user directory. It may need to be created for the relevant user:

To have a timer run while the user is not logged in, be sure to enable lingering sessions:

Slow shutdowns or reboot times due to running services

Problem

Occasionally a systemd system or user service will cause the system to greatly delay poweroff/shutdown or reboot operation due to systemd default wait times for the operation blocking service to time out.

Solution

To greatly speed up this operation, the default timeout values can be reduced at the expense of the service (potentially) not cleanly finishing a task. In order to be effective, both of the following configuration changes must be put into effect to shorten the default timeout system and user services.

Make sure to enable the cryptsetup USE flag for sys-apps/systemd. It will install /lib/systemd/system-generators/systemd-cryptsetup-generator that will automatically create a service (cryptsetup@crypt-home.service for above example) for each entry on boot.

! scope="col" width="15%" | Boot parameter ! scope="col" width="15%" | Supported options ! Description |-

| fsck.mode | auto
force
skip | Controls the mode of operation. The default is auto, and ensures that file system checks are done when the file system checker deems them necessary. force unconditionally results in full file system checks. skip skips any file system checks. |-

| fsck.repair | preen
yes
no | Controls the mode of operation. The default is preen, and will automatically repair problems that can be safely fixed. yes will answer yes to all questions by fsck and no will answer no to all questions. |-

|}

Optional systemd binaries

Many optional systemd binaries can be built by setting certain use flags. An incomplete mapping of USE flag to binary is below.