Merge pull request #2088 from ybduan/rng_builtin

rng_builtin: add 'rng-builtin' support for virtio_mode.with_viorng

qemu/tests/cfg/virtio_mode.cfg

@@ -29,14 +29,24 @@
             pci_id_pattern = "(\d+:\d+\.\d+)\s+Ethernet controller:.*?Virtio network device"
         - with_viorng:
             driver_name = viorng
-            no_virtio_rng:
-                virtio_rngs += " rng0"
-                backend_rng0 = rng-random
-                backend_type = passthrough
-                filename_passthrough = /dev/urandom
             device_type = "virtio-rng-pci"
             device_name = "VirtIO RNG Device"
             pci_id_pattern = "(\d+:\d+\.\d+)\s+Unclassified device\s.*?Virtio RNG"
+            no_virtio_rng:
+                virtio_rngs += " rng0"
+            variants:
+                - with_rng_builtin:
+                    only no_virtio_rng
+                    required_qemu = [4.2, )
+                    backend_rng0 = rng-builtin
+                    backend_type = builtin
+                - with_rng_random:
+                    only no_virtio_rng
+                    backend_rng0 = rng-random
+                    backend_type = passthrough
+                    filename_passthrough = /dev/urandom
+                - @default:
+                    only virtio_rng
         - with_viostor:
             only virtio_blk
             driver_name = viostor