Users who wish to keep the classic daemon can set: `services.dbus.implementation = "dbus";`
- The NixOS integration test driver now supports `systemd-nspawn` containers as an alternative backend to QEMU virtual machines ([#470248](https://github.com/NixOS/nixpkgs/pull/470248), [#478109](https://github.com/NixOS/nixpkgs/pull/478109), [#479968](https://github.com/NixOS/nixpkgs/pull/479968)).
Most NixOS integration tests do not require a full VM, and switching them to containers can considerably reduce test time and resource usage.
Container-based tests also run fine on Nix builders that are themselves VMs without KVM, and because containers can bind-mount host device nodes, they make it possible to exercise GPU/CUDA workloads from within NixOS integration tests.
See [the NixOS manual section on writing tests](https://nixos.org/manual/nixos/stable/#sec-writing-nixos-tests) for details on how to opt in and on the limitations of the container backend.
## New Modules {#sec-release-26.05-new-modules}
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