nixos/incus: fix OVMF path for existing VMs

  }'';

  # https://github.com/lxc/incus/blob/cff35a29ee3d7a2af1f937cbb6cf23776941854b/internal/server/instance/drivers/driver_qemu.go#L123

  OVMF2MB = pkgs.OVMF.override {

    secureBoot = true;

    fdSize2MB = true;

  };

  ovmf-prefix = if pkgs.stdenv.hostPlatform.isAarch64 then "AAVMF" else "OVMF";

  ovmf = pkgs.linkFarm "incus-ovmf" [

    # 2MB must remain the default or existing VMs will fail to boot. New VMs will prefer 4MB

    {

      name = "OVMF_CODE.fd";

      path = "${OVMF2MB.fd}/FV/${ovmf-prefix}_CODE.fd";

    }

    {

      name = "OVMF_VARS.fd";

      path = "${OVMF2MB.fd}/FV/${ovmf-prefix}_VARS.fd";

    }

    {

      name = "OVMF_VARS.ms.fd";

      path = "${OVMF2MB.fd}/FV/${ovmf-prefix}_VARS.fd";

    }

    {

      name = "OVMF_CODE.4MB.fd";

      path = "${pkgs.OVMFFull.fd}/FV/${ovmf-prefix}_CODE.fd";