With this patch the RTL8169 on a Gigabyte GA-Z68MA-D2H-B3 motherboard works for me.

Reference: /n/sources/patch/applied/ether8169-macv34
Date: Fri Oct 18 23:32:30 CES 2013
Signed-off-by: davide+p9@cs.cmu.edu

--- /sys/src/9/pc/ether8169.c	Fri Oct 18 23:32:17 2013
+++ /sys/src/9/pc/ether8169.c	Fri Oct 18 23:32:16 2013
@@ -114,6 +114,7 @@
 //	Macv19		= 0x3c000000,	/* dup Macv12a: RTL8111c-gr */
 	Macv25		= 0x28000000,	/* RTL8168D */
 	Macv2c		= 0x2c000000,	/* RTL8168E */
+	Macv34		= 0x2c800000,	/* RTL8168E */
 	Ifg0		= 0x01000000,	/* Interframe Gap 0 */
 	Ifg1		= 0x02000000,	/* Interframe Gap 1 */
 };
@@ -739,6 +740,7 @@
 	case Macv15:
 	case Macv25:
 	case Macv2c:
+	case Macv34:
 		break;
 	}
 
@@ -1094,6 +1096,7 @@
 	case Macv15:
 	case Macv25:
 	case Macv2c:
+	case Macv34:
 		break;
 	}
 	return 0;