diff --git a/sys/arch/arm/gemini/files.gemini b/sys/arch/arm/gemini/files.gemini
index a390d75f16ff..a023f51e937d 100644
--- a/sys/arch/arm/gemini/files.gemini
+++ b/sys/arch/arm/gemini/files.gemini
@@ -1,4 +1,4 @@
-#	$NetBSD: files.gemini,v 1.4 2008/11/11 19:54:38 cliff Exp $
+#	$NetBSD: files.gemini,v 1.5 2008/11/13 07:21:59 cliff Exp $
 #
 # Configuration info for GEMINI CPU support
 # Based on omap/files.omap2
@@ -11,6 +11,7 @@ file	arch/arm/arm32/irq_dispatch.S
 # Memory size in megabytes
 defparam opt_gemini.h				MEMSIZE
 defflag opt_gemini.h				GEMINI
+defparam opt_gemini.h				GEMINI_BUSBASE: GEMINI
 defflag opt_gemini.h				SL3516: GEMINI
 defflag opt_gemini.h				GEMINI_MASTER: GEMINI
 defflag opt_gemini.h				GEMINI_SLAVE: GEMINI
diff --git a/sys/arch/arm/gemini/gemini_obio.c b/sys/arch/arm/gemini/gemini_obio.c
index 5c817c84775d..38420ccd2109 100644
--- a/sys/arch/arm/gemini/gemini_obio.c
+++ b/sys/arch/arm/gemini/gemini_obio.c
@@ -1,12 +1,13 @@
-/*	$NetBSD: gemini_obio.c,v 1.5 2008/11/13 05:03:05 cliff Exp $	*/
+/*	$NetBSD: gemini_obio.c,v 1.6 2008/11/13 07:21:59 cliff Exp $	*/
 
 /* adapted from:
- *	$Id: gemini_obio.c,v 1.5 2008/11/13 05:03:05 cliff Exp $
+ *      NetBSD: omap2_obio.c,v 1.5 2008/10/21 18:50:25 matt Exp
  */
 
 /*
- * Autoconfiguration support for the Texas Instruments OMAP "On Board" I/O.
+ * Autoconfiguration support for the Gemini "On Board" I/O.
  *
+ * Based on arm/omap/omap2_obio.c which in turn was derived
  * Based on arm/omap/omap_emifs.c which in turn was derived
  * Based on arm/xscale/pxa2x0.c which in turn was derived
  * from arm/sa11x0/sa11x0.c
@@ -103,7 +104,7 @@
 
 #include "opt_gemini.h"
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gemini_obio.c,v 1.5 2008/11/13 05:03:05 cliff Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gemini_obio.c,v 1.6 2008/11/13 07:21:59 cliff Exp $");
 
 #include "locators.h"
 #include "obio.h"
@@ -164,9 +165,9 @@ obio_attach(device_t parent, device_t self, void *aux)
 
 	aprint_normal(": On-Board IO\n");
 
-#ifdef GEMINI_SLAVE
+#if (GEMINI_BUSBASE != 0)
 	sc->sc_dmarange.dr_sysbase = 0;
-	sc->sc_dmarange.dr_busbase = (128 - MEMSIZE) * 1024 * 1024;
+	sc->sc_dmarange.dr_busbase = (GEMINI_BUSBASE * 1024 * 1024);
 	sc->sc_dmarange.dr_len = MEMSIZE * 1024 * 1024;
 	gemini_bus_dma_tag._ranges = &sc->sc_dmarange;
 	gemini_bus_dma_tag._nranges = 1;
diff --git a/sys/arch/arm/gemini/gemini_pci.c b/sys/arch/arm/gemini/gemini_pci.c
index ed2cfe23f565..9381175be9b5 100644
--- a/sys/arch/arm/gemini/gemini_pci.c
+++ b/sys/arch/arm/gemini/gemini_pci.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: gemini_pci.c,v 1.4 2008/11/13 05:03:05 cliff Exp $	*/
+/*	$NetBSD: gemini_pci.c,v 1.5 2008/11/13 07:21:59 cliff Exp $	*/
 
 /* adapted from:
  *	NetBSD: i80312_pci.c,v 1.9 2005/12/11 12:16:51 christos Exp
@@ -44,7 +44,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gemini_pci.c,v 1.4 2008/11/13 05:03:05 cliff Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gemini_pci.c,v 1.5 2008/11/13 07:21:59 cliff Exp $");
 
 #include <sys/cdefs.h>
 
@@ -225,16 +225,9 @@ gemini_pci_init(pci_chipset_tag_t pc, void *cookie)
 
 	pci_configure_bus(pc, ioext, memext, NULL, 0, arm_dcache_align);
 
-#if defined(GEMINI_SLAVE)
 	gemini_pci_conf_write(sc, 0, GEMINI_PCI_CFG_REG_MEM1,
-		PCI_CFG_REG_MEM_BASE(
-		    GEMINI_DRAM_BASE + ((128 - MEMSIZE) *  1024 * 1024))
-			| gemini_pci_cfg_reg_mem_size(MEMSIZE * 1024 * 1024));
-#else
-	gemini_pci_conf_write(sc, 0, GEMINI_PCI_CFG_REG_MEM1,
-		PCI_CFG_REG_MEM_BASE(GEMINI_DRAM_BASE)
-			| gemini_pci_cfg_reg_mem_size(MEMSIZE * 1024 * 1024));
-#endif
+		PCI_CFG_REG_MEM_BASE((GEMINI_DRAM_BASE + (GEMINI_BUSBASE * 1024 * 1024)))
+		| gemini_pci_cfg_reg_mem_size(MEMSIZE * 1024 * 1024));
 
 	extent_destroy(ioext);
 	extent_destroy(memext);
diff --git a/sys/arch/evbarm/conf/GEMINI b/sys/arch/evbarm/conf/GEMINI
index 4b8ee68ca098..4caff70f5cb4 100644
--- a/sys/arch/evbarm/conf/GEMINI
+++ b/sys/arch/evbarm/conf/GEMINI
@@ -157,6 +157,9 @@ cpu0		at mainbus?
 # Specify the memory size in megabytes.
 options		MEMSIZE=128
 
+# Specify the (DMA) Bus Address base in megabytes
+options		GEMINI_BUSBASE=0
+
 # On-board IO
 obio0		at mainbus?
 
diff --git a/sys/arch/evbarm/conf/GEMINI_MASTER b/sys/arch/evbarm/conf/GEMINI_MASTER
index 1318614ed388..7cb5d3b625f6 100644
--- a/sys/arch/evbarm/conf/GEMINI_MASTER
+++ b/sys/arch/evbarm/conf/GEMINI_MASTER
@@ -156,6 +156,9 @@ cpu0		at mainbus?
 # Specify the memory size in megabytes.
 options		MEMSIZE=64
 
+# Specify the (DMA) Bus Address base in megabytes
+options		GEMINI_BUSBASE=0
+
 # On-board IO
 obio0		at mainbus?
 
diff --git a/sys/arch/evbarm/conf/GEMINI_SLAVE b/sys/arch/evbarm/conf/GEMINI_SLAVE
index 86a376a1835f..7456bf8ca0b3 100644
--- a/sys/arch/evbarm/conf/GEMINI_SLAVE
+++ b/sys/arch/evbarm/conf/GEMINI_SLAVE
@@ -156,6 +156,9 @@ cpu0		at mainbus?
 # Specify the memory size in megabytes.
 options		MEMSIZE=64
 
+# Specify the (DMA) Bus Address base in megabytes
+options		GEMINI_BUSBASE=64
+
 # On-board IO
 obio0		at mainbus?