Merge pull request #228347 from NixOS/uefi-without-bootloaders

      # Create a directory for exchanging data with the VM.

      mkdir -p "$TMPDIR/xchg"

      ${lib.optionalString cfg.useBootLoader

      ''

        NIX_EFI_VARS=$(readlink -f "''${NIX_EFI_VARS:-${config.system.name}-efi-vars.fd}")

      ${lib.optionalString cfg.useEFIBoot

      ''

        # Expose EFI variables, it's useful even when we are not using a bootloader (!).

        # We might be interested in having EFI variable storage present even if we aren't booting via UEFI, hence

        # no guard against `useBootLoader`.  Examples:

        # - testing PXE boot or other EFI applications

        # - directbooting LinuxBoot, which `kexec()s` into a UEFI environment that can boot e.g. Windows

        NIX_EFI_VARS=$(readlink -f "''${NIX_EFI_VARS:-${config.system.name}-efi-vars.fd}")

        # VM needs writable EFI vars

        if ! test -e "$NIX_EFI_VARS"; then

            cp ${systemImage}/efi-vars.fd "$NIX_EFI_VARS"

        ${if cfg.useBootLoader then

            # We still need the EFI var from the make-disk-image derivation

            # because our "switch-to-configuration" process might

            # write into it and we want to keep this data.

            ''cp ${systemImage}/efi-vars.fd "$NIX_EFI_VARS"''

            else

            ''cp ${cfg.efi.variables} "$NIX_EFI_VARS"''

          }

          chmod 0644 "$NIX_EFI_VARS"

        fi

      ''}

      ''}

      cd "$TMPDIR"