Highlights of new systemd 248 features include:
- A new concept of "system extension images" as images that can extend the /usr/ or /opt/ hierarchies at run-time with additional files. The images can be read-only and its usr/opt hierarchies combined via OverlayFS. This led to a new systemd-sysext tool with systemd 248 for managing of system extension hierarchies.
- A new "root=tmpfs" kernel command-line option that will mount a Tmpfs on / . The mount.usr option can then be used to point to the operating system implementation.
- Systemd-networkd now supports the B.A.T.M.A.N. Advanced Wireless Routing Protocol. The "Better Approach to Mobile Ad-hoc Networking" is a routing protocol for multi-hop mobile ad-hoc networks.
- Intel SGX enclave device nodes will now be owned by a new system security group called "sgx".
- A new /etc/veritytab configuration file for configuring dm-verity integrity protection for block devices.
- Systemd-cryptsetup can now unlock LUKS2 volumes using TPM2 hardware and FIDO2 security tokens.
- A new systemd-cryptenroll tool for adding TPM2 / FIDO2 / PKCS#11 security tokens to LUKS volumes.
- A new ConditionCPUFeature= setting that can conditionalize systemd units so they only run if matching given CPU features like RdRand.
- Various systemd-resolved improvements.
- The previously introduced systemd-oomd out-of-memory daemon now has a default memory pressure duration tunable and this service is also now considered fully-supported rather than just experimental.
- Systemd has renamed its main Git development branch from "master" to "main".
- Systemd will now set the $SYSTEMD_EXEC_PID environment variable for the spawned process to the PID of the process itself.
The lengthy list of systemd 248 changes in full can be found via their NEWS file . Those wanting to build systemd 248 from source can fetch it via GitHub .