systemd: use mkDefault for oomd.enable to allow downstream override#1028
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SuperSandro2000 merged 2 commits intonix-community:mainfrom Apr 15, 2026
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systemd-oomd was unconditionally disabled with a bare `false` because older WSL2 kernels lacked CONFIG_PSI (Pressure Stall Information). Modern WSL2 kernels (6.1+, including the current 6.6.x series) support PSI via /proc/pressure/*, making systemd-oomd functional. Change from bare `false` to `lib.mkDefault false` so downstream NixOS-WSL consumers on modern kernels can re-enable oomd with a simple `systemd.oomd.enable = true` (or mkDefault true) without needing mkForce. The default behavior is unchanged — oomd remains disabled unless explicitly enabled by the consumer.
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Summary
falsetolib.mkDefault falseforsystemd.oomd.enable/proc/pressure/*), making systemd-oomd functionalMotivation
Downstream NixOS-WSL consumers using cgroup-based memory limits (e.g., for nix evaluation guards) need systemd-oomd for
ManagedOOMMemoryPressure=killon custom slices. Currently this requiresmkForceto override the barefalse, which is unnecessarily heavy.Testing
Verified on WSL2 kernel 6.6.87.2-microsoft-standard-WSL2:
/proc/pressure/memoryreturns valid PSI datasystemd-oomd.servicestarts and runs correctly after overrideManagedOOMMemoryPressure=killon custom slices works as expected