Index: stand/efi/loader/bootinfo.c
===================================================================
--- stand/efi/loader/bootinfo.c
+++ stand/efi/loader/bootinfo.c
@@ -119,6 +119,14 @@
 				    NULL, NULL);
 			}
 		}
+		if (getenv("efi_com_mmio") != NULL &&
+		    getenv("efi_com_speed") != NULL && /* verifies uart mode */
+		    getenv("hw.uart.console") == NULL) {
+			snprintf(buf, sizeof(buf), "mm:%s,rs:2",
+			    getenv("efi_com_mmio"));
+			env_setenv("hw.uart.console", EV_VOLATILE, buf, NULL,
+			    NULL);
+		}
 #endif
 	}
 
Index: stand/efi/loader/main.c
===================================================================
--- stand/efi/loader/main.c
+++ stand/efi/loader/main.c
@@ -736,6 +736,15 @@
 	setenv(key, buf, 1);
 }
 
+static void
+setenv_addr(const char *key, uint64_t addr)
+{
+	char buf[30];
+
+	snprintf(buf, sizeof(buf), "0x%llx", addr);
+	setenv(key, buf, 1);
+}
+
 /*
  * Parse ConOut (the list of consoles active) and see if we can find a
  * serial port and/or a video port. It would be nice to also walk the
@@ -752,6 +761,7 @@
 	EFI_DEVICE_PATH *node;
 	ACPI_HID_DEVICE_PATH  *acpi;
 	UART_DEVICE_PATH  *uart;
+	VENDOR_DEVICE_PATH *hw;
 	bool pci_pending;
 
 	how = 0;
@@ -801,6 +811,14 @@
 			 * so only match it if it's last.
 			 */
 			pci_pending = true;
+		} else if (DevicePathType(node) == HARDWARE_DEVICE_PATH &&
+		    DevicePathSubType(node) == HW_VENDOR_DP) {
+			hw = (void *)node;
+
+			if (DevicePathNodeLength(&hw->Header) ==
+			    sizeof(*hw) + sizeof(uint64_t)) {
+				setenv_addr("efi_com_mmio", *(uint64_t *)(hw + 1));
+			}
 		}
 		node = NextDevicePathNode(node);
 	}