diff --git a/sys/dev/pci/if_sip.c b/sys/dev/pci/if_sip.c
index 7681fac0f5aa..bdf8336d6b22 100644
--- a/sys/dev/pci/if_sip.c
+++ b/sys/dev/pci/if_sip.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: if_sip.c,v 1.45 2002/02/09 21:04:02 thorpej Exp $	*/
+/*	$NetBSD: if_sip.c,v 1.46 2002/02/28 19:10:16 thorpej Exp $	*/
 
 /*-
  * Copyright (c) 2001, 2002 The NetBSD Foundation, Inc.
@@ -82,7 +82,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_sip.c,v 1.45 2002/02/09 21:04:02 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_sip.c,v 1.46 2002/02/28 19:10:16 thorpej Exp $");
 
 #include "bpfilter.h"
 
@@ -145,6 +145,12 @@ __KERNEL_RCSID(0, "$NetBSD: if_sip.c,v 1.45 2002/02/09 21:04:02 thorpej Exp $");
 #define	SIP_NTXDESC_MASK	(SIP_NTXDESC - 1)
 #define	SIP_NEXTTX(x)		(((x) + 1) & SIP_NTXDESC_MASK)
 
+#if defined(DP83020)
+#define	TX_DMAMAP_SIZE		ETHER_MAX_LEN_JUMBO
+#else
+#define	TX_DMAMAP_SIZE		MCLBYTES
+#endif
+
 /*
  * Receive descriptor list size.  We have one Rx buffer per incoming
  * packet, so this logic is a little simpler.
@@ -588,6 +594,17 @@ SIP_DECL(attach)(struct device *parent, struct device *self, void *aux)
 
 	sc->sc_model = sip;
 
+	/*
+	 * XXX Work-around broken PXE firmware on some boards.
+	 *
+	 * The DP83815 shares an address decoder with the MEM BAR
+	 * and the ROM BAR.  Make sure the ROM BAR is disabled,
+	 * so that memory mapped access works.
+	 */
+	pci_conf_write(pa->pa_pc, pa->pa_tag, PCI_MAPREG_ROM,
+	    pci_conf_read(pa->pa_pc, pa->pa_tag, PCI_MAPREG_ROM) &
+	    ~PCI_MAPREG_ROM_ENABLE);
+
 	/*
 	 * Map the device.
 	 */
@@ -711,7 +728,7 @@ SIP_DECL(attach)(struct device *parent, struct device *self, void *aux)
 	 * Create the transmit buffer DMA maps.
 	 */
 	for (i = 0; i < SIP_TXQUEUELEN; i++) {
-		if ((error = bus_dmamap_create(sc->sc_dmat, MCLBYTES,
+		if ((error = bus_dmamap_create(sc->sc_dmat, TX_DMAMAP_SIZE,
 		    SIP_NTXSEGS, MCLBYTES, 0, 0,
 		    &sc->sc_txsoft[i].txs_dmamap)) != 0) {
 			printf("%s: unable to create tx DMA map %d, "
@@ -870,6 +887,40 @@ SIP_DECL(attach)(struct device *parent, struct device *self, void *aux)
 	if_attach(ifp);
 	ether_ifattach(ifp, enaddr);
 
+	/*
+	 * The number of bytes that must be available in
+	 * the Tx FIFO before the bus master can DMA more
+	 * data into the FIFO.
+	 */
+	sc->sc_tx_fill_thresh = 64 / 32;
+
+	/*
+	 * Start at a drain threshold of 512 bytes.  We will
+	 * increase it if a DMA underrun occurs.
+	 *
+	 * XXX The minimum value of this variable should be
+	 * tuned.  We may be able to improve performance
+	 * by starting with a lower value.  That, however,
+	 * may trash the first few outgoing packets if the
+	 * PCI bus is saturated.
+	 */
+	sc->sc_tx_drain_thresh = 512 / 32;
+
+	/*
+	 * Initialize the Rx FIFO drain threshold.  We want to start
+	 * dumping the packet into memory very quickly, especially
+	 * at Gigabot speeds (the value we use is very aggressive).
+	 * This is in units of 8 bytes.
+	 *
+	 * We should never set this value lower than 2; 14 bytes are
+	 * required to filter the packet.
+	 */
+#if 0
+	sc->sc_rx_drain_thresh = 4;
+#else
+	sc->sc_rx_drain_thresh = RXCFG_DRTH >> RXCFG_DRTH_SHIFT;
+#endif
+
 #ifdef SIP_EVENT_COUNTERS
 	/*
 	 * Attach event counters.
@@ -2076,31 +2127,6 @@ SIP_DECL(init)(struct ifnet *ifp)
 	 */
 	bus_space_write_4(st, sh, SIP_CFG, sc->sc_cfg);
 
-	/*
-	 * Initialize the transmit fill and drain thresholds if
-	 * we have never done so.
-	 */
-	if (sc->sc_tx_fill_thresh == 0) {
-		/*
-		 * XXX This value should be tuned.  We may be able to
-		 * improve performance by increasing it.
-		 */
-		sc->sc_tx_fill_thresh = 64/32;
-	}
-	if (sc->sc_tx_drain_thresh == 0) {
-		/*
-		 * Start at a drain threshold of 512 bytes.  We will
-		 * increase it if a DMA underrun occurs.
-		 *
-		 * XXX The minimum value of this variable should be
-		 * tuned.  We may be able to improve performance
-		 * by starting with a lower value.  That, however,
-		 * may trash the first few outgoing packets if the
-		 * PCI bus is saturated.
-		 */
-		sc->sc_tx_drain_thresh = 512 / 32;
-	}
-
 	/*
 	 * Initialize the prototype TXCFG register.
 	 */