I've added the device IDs for the nForce4 SATA devices. It's 
been tested on an Asus A8N5X with 2 drives on each of the 
2 devices. DMA seems to be working fine.

The nVidia device IDs in the boot code have been brought into 
sync with the kernel.

Reference: /n/sources/patch/applied/nforce4-sata
Date: Tue Aug  8 18:36:39 CES 2006
Signed-off-by: ejsherry@cgl.uwaterloo.ca

--- /sys/src/9/pc/sdata.c	Tue Aug  8 18:31:08 2006
+++ /sys/src/9/pc/sdata.c	Tue Aug  8 18:31:06 2006
@@ -1966,6 +1966,8 @@
 		case (0x00E5<<16)|0x10DE:	/* nVidia nForce3 Pro */
 		case (0x0035<<16)|0x10DE:	/* nVidia nForce3 MCP */
 		case (0x0053<<16)|0x10DE:	/* nVidia nForce4 */
+		case (0x0054<<16)|0x10DE:	/* nVidia nForce4 SATA */
+		case (0x0055<<16)|0x10DE:	/* nVidia nForce4 SATA */
 			/*
 			 * Ditto, although it may have a different base
 			 * address for the registers (0x50?).
--- /sys/src/boot/pc/sdata.c	Tue Aug  8 18:31:14 2006
+++ /sys/src/boot/pc/sdata.c	Tue Aug  8 18:31:12 2006
@@ -1506,7 +1506,15 @@
 			 * This can probably be lumped in with the 768 above.
 			 */
 			/*FALLTHROUGH*/
+		case (0x01BC<<16)|0x10DE:	/* nVidia nForce1 */
+		case (0x0065<<16)|0x10DE:	/* nVidia nForce2 */
+		case (0x0085<<16)|0x10DE:	/* nVidia nForce2 MCP */
 		case (0x00D5<<16)|0x10DE:	/* nVidia nForce3 */
+		case (0x00E5<<16)|0x10DE:	/* nVidia nForce3 Pro */
+		case (0x0035<<16)|0x10DE:	/* nVidia nForce3 MCP */
+		case (0x0053<<16)|0x10DE:	/* nVidia nForce4 */
+		case (0x0054<<16)|0x10DE:	/* nVidia nForce4 SATA */
+		case (0x0055<<16)|0x10DE:	/* nVidia nForce4 SATA */
 			/*
 			 * Ditto, although it may have a different base
 			 * address for the registers (0x50?).