Index: sys/dev/bge/if_bgereg.h
===================================================================
--- sys/dev/bge/if_bgereg.h	(revision 209954)
+++ sys/dev/bge/if_bgereg.h	(working copy)
@@ -77,6 +77,8 @@
 #define	BGE_SOFTWARE_GENCOMM_FW		0x00000B78
 #define	BGE_SOFTWARE_GENNCOMM_FW_LEN	0x00000B7C
 #define	BGE_SOFTWARE_GENNCOMM_FW_DATA	0x00000B80
+#define	BGE_SRAM_MAC_ADDR_HIGH_MBOX	0x00000C14
+#define	BGE_SRAM_MAC_ADDR_LOW_MBOX	0x00000C18
 #define	BGE_SOFTWARE_GENCOMM_END	0x00000FFF
 #define	BGE_UNMAPPED			0x00001000
 #define	BGE_UNMAPPED_END		0x00001FFF
Index: sys/dev/bge/if_bge.c
===================================================================
--- sys/dev/bge/if_bge.c	(revision 209954)
+++ sys/dev/bge/if_bge.c	(working copy)
@@ -5203,17 +5203,21 @@
 static int
 bge_get_eaddr_mem(struct bge_softc *sc, uint8_t ether_addr[])
 {
+	uint8_t inv_addr[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
 	uint32_t mac_addr;
 
-	mac_addr = bge_readmem_ind(sc, 0x0c14);
+	mac_addr = bge_readmem_ind(sc, BGE_SRAM_MAC_ADDR_HIGH_MBOX);
 	if ((mac_addr >> 16) == 0x484b) {
 		ether_addr[0] = (uint8_t)(mac_addr >> 8);
 		ether_addr[1] = (uint8_t)mac_addr;
-		mac_addr = bge_readmem_ind(sc, 0x0c18);
+		mac_addr = bge_readmem_ind(sc, BGE_SRAM_MAC_ADDR_LOW_MBOX);
 		ether_addr[2] = (uint8_t)(mac_addr >> 24);
 		ether_addr[3] = (uint8_t)(mac_addr >> 16);
 		ether_addr[4] = (uint8_t)(mac_addr >> 8);
 		ether_addr[5] = (uint8_t)mac_addr;
+		/* Old bootcode can report all 0s in SRAM. */
+		if (bcmp(ether_addr, inv_addr, sizeof(inv_addr)) == 0)
+			return (1);
 		return (0);
 	}
 	return (1);