- Support for mounting filesystems from block devices protected with [dm-verity](https://docs.kernel.org/admin-guide/device-mapper/verity.html)
was added through the `boot.initrd.systemd.dmVerity` option.
- The [Xen Hypervisor](https://xenproject.org) is once again available as a virtualisation option under [`virtualisation.xen`](#opt-virtualisation.xen.enable).
- The [Xen Project Hypervisor](https://xenproject.org) is once again available as a virtualisation option under [`virtualisation.xen`](#opt-virtualisation.xen.enable).
- This release includes Xen [4.17.5](https://wiki.xenproject.org/wiki/Xen_Project_4.17_Release_Notes), [4.18.3](https://wiki.xenproject.org/wiki/Xen_Project_4.18_Release_Notes) and [4.19.0](https://wiki.xenproject.org/wiki/Xen_Project_4.19_Release_Notes), as well as support for booting the hypervisor on EFI systems.
::: {.warning}
Booting into Xen through a legacy BIOS bootloader or with the legacy script-based Stage 1 initrd have been **deprecated**. Only EFI booting and the new systemd-based Stage 1 initrd are supported.
Booting into the Xen Project Hypervisor through a legacy BIOS bootloader or with the legacy script-based Stage 1 initrd have been **deprecated**. Only EFI booting and the new systemd-based Stage 1 initrd are supported.
:::
- There are two flavours of Xen available by default: `xen`, which includes all built-in components, and `xen-slim`, which replaces the built-in components with their Nixpkgs equivalents.
- The `qemu-xen-traditional` component has been deprecated by upstream Xen, and is no longer available in any of the Xen packages.
- The `qemu-xen-traditional` component has been deprecated by the upstream Xen Project, and is no longer available in any of the Xen Project Hypervisor packages.
- The OCaml-based Xen Store can now be configured using [`virtualisation.xen.store.settings`](#opt-virtualisation.xen.store.settings).
- The `virtualisation.xen.bridge` options have been deprecated in this release cycle. Users who need network bridges are encouraged to set up their own networking configurations.
[[$# -ne 1 ]]&&echo-e"\e[1;31merror:\e[0m xenBootBuilder must be called with exactly one verbosity argument. See the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option."&&exit 1
"debug")echo-e"\e[1;34mxenBootBuilder:\e[0m called with the '$1' flag";;
*)
echo-e"\e[1;31merror:\e[0m xenBootBuilder was called with an invalid argument. See the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option."