Index: mfi_disk.c
===================================================================
--- mfi_disk.c	(revision 227335)
+++ mfi_disk.c	(working copy)
@@ -35,6 +35,7 @@
 #include <sys/selinfo.h>
 #include <sys/module.h>
 #include <sys/malloc.h>
+#include <sys/sysctl.h>
 #include <sys/uio.h>
 
 #include <sys/bio.h>
Index: mfi_pci.c
===================================================================
--- mfi_pci.c	(revision 227335)
+++ mfi_pci.c	(working copy)
@@ -66,6 +66,7 @@
 #include <sys/conf.h>
 #include <sys/bio.h>
 #include <sys/malloc.h>
+#include <sys/sysctl.h>
 #include <sys/uio.h>
 
 #include <machine/bus.h>
@@ -107,6 +108,11 @@
 DRIVER_MODULE(mfi, pci, mfi_pci_driver, mfi_devclass, 0, 0);
 MODULE_VERSION(mfi, 1);
 
+static int	mfi_msix = 0;
+TUNABLE_INT("hw.mfi.msix", &mfi_msix);
+SYSCTL_INT(_hw_mfi, OID_AUTO, msix, CTLFLAG_RDTUN, &mfi_msix, 0,
+    "Enable use of MSI-X interrupts");
+
 struct mfi_ident {
 	uint16_t	vendor;
 	uint16_t	device;
@@ -169,7 +175,7 @@
 	struct mfi_softc *sc;
 	struct mfi_ident *m;
 	uint32_t command;
-	int error;
+	int count, error;
 
 	sc = device_get_softc(dev);
 	bzero(sc, sizeof(*sc));
@@ -226,6 +232,29 @@
 		goto out;
 	}
 
+	/* Allocate IRQ resource. */
+	sc->mfi_irq_rid = 0;
+	switch (pci_get_device(sc->mfi_dev)) {
+	case 0x0060:	/* SAS1078R */
+	case 0x007c:	/* SAS1078DE */
+	case 0x0413:	/* Verde ZCR */
+		/* Do not use MSI-X for these systems. */
+		break;
+	default:
+		count = 1;
+		if (mfi_msix && pci_alloc_msix(sc->mfi_dev, &count) == 0) {
+			device_printf(sc->mfi_dev, "Using MSI-X\n");
+			sc->mfi_irq_rid = 1;
+		}
+		break;
+	}
+	if ((sc->mfi_irq = bus_alloc_resource_any(sc->mfi_dev, SYS_RES_IRQ,
+	    &sc->mfi_irq_rid, RF_SHAREABLE | RF_ACTIVE)) == NULL) {
+		device_printf(sc->mfi_dev, "Cannot allocate interrupt\n");
+		error = EINVAL;
+		goto out;
+	}
+
 	error = mfi_attach(sc);
 out:
 	if (error) {
@@ -280,6 +309,8 @@
 		bus_release_resource(sc->mfi_dev, SYS_RES_MEMORY,
 		    sc->mfi_regs_rid, sc->mfi_regs_resource);
 	}
+	if (sc->mfi_irq_rid != 0)
+		pci_release_msi(sc->mfi_dev);
 
 	return;
 }
Index: mfivar.h
===================================================================
--- mfivar.h	(revision 227335)
+++ mfivar.h	(working copy)
@@ -395,6 +395,7 @@
 	(sc)->mfi_bhandle, (reg))
 
 MALLOC_DECLARE(M_MFIBUF);
+SYSCTL_DECL(_hw_mfi);
 
 #define MFI_CMD_TIMEOUT 30
 #define MFI_MAXPHYS (128 * 1024)
Index: mfi.c
===================================================================
--- mfi.c	(revision 227335)
+++ mfi.c	(working copy)
@@ -117,7 +117,7 @@
 static void 	mfi_issue_cmd_xscale(struct mfi_softc *sc,uint32_t bus_add,uint32_t frame_cnt);
 static void 	mfi_issue_cmd_ppc(struct mfi_softc *sc,uint32_t bus_add,uint32_t frame_cnt);
 
-static SYSCTL_NODE(_hw, OID_AUTO, mfi, CTLFLAG_RD, 0, "MFI driver parameters");
+SYSCTL_NODE(_hw, OID_AUTO, mfi, CTLFLAG_RD, 0, "MFI driver parameters");
 static int	mfi_event_locale = MFI_EVT_LOCALE_ALL;
 TUNABLE_INT("hw.mfi.event_locale", &mfi_event_locale);
 SYSCTL_INT(_hw_mfi, OID_AUTO, event_locale, CTLFLAG_RW, &mfi_event_locale,
@@ -157,6 +157,9 @@
 mfi_enable_intr_xscale(struct mfi_softc *sc)
 {
 	MFI_WRITE4(sc, MFI_OMSK, 0x01);
+
+	/* Dummy read to force PCI flush. */
+	(void)MFI_READ4(sc, MFI_OMSK);
 }
 
 static void
@@ -168,6 +171,9 @@
 	} else if (sc->mfi_flags & MFI_FLAGS_GEN2) {
 		MFI_WRITE4(sc, MFI_OMSK, ~MFI_GEN2_EIM);
 	}
+
+	/* Dummy read to force PCI flush. */
+	(void)MFI_READ4(sc, MFI_OMSK);
 }
 
 static int32_t
@@ -192,6 +198,9 @@
 		return 1;
 
 	MFI_WRITE4(sc, MFI_OSTS, status);
+
+	/* Dummy read to force PCI flush. */
+	(void)MFI_READ4(sc, MFI_OSTS);
 	return 0;
 }
 
@@ -212,6 +221,9 @@
 	}
 
 	MFI_WRITE4(sc, MFI_ODCR0, status);
+
+	/* Dummy read to force PCI flush. */
+	(void)MFI_READ4(sc, MFI_OSTS);
 	return 0;
 }
 
@@ -484,15 +496,8 @@
 	mtx_unlock(&sc->mfi_io_lock);
 
 	/*
-	 * Set up the interrupt handler.  XXX This should happen in
-	 * mfi_pci.c
+	 * Set up the interrupt handler.
 	 */
-	sc->mfi_irq_rid = 0;
-	if ((sc->mfi_irq = bus_alloc_resource_any(sc->mfi_dev, SYS_RES_IRQ,
-	    &sc->mfi_irq_rid, RF_SHAREABLE | RF_ACTIVE)) == NULL) {
-		device_printf(sc->mfi_dev, "Cannot allocate interrupt\n");
-		return (EINVAL);
-	}
 	if (bus_setup_intr(sc->mfi_dev, sc->mfi_irq, INTR_MPSAFE|INTR_TYPE_BIO,
 	    NULL, mfi_intr, sc, &sc->mfi_intr)) {
 		device_printf(sc->mfi_dev, "Cannot set up interrupt\n");
Index: mfi_cam.c
===================================================================
--- mfi_cam.c	(revision 227335)
+++ mfi_cam.c	(working copy)
@@ -45,6 +45,7 @@
 #include <sys/uio.h>
 #include <sys/proc.h>
 #include <sys/signalvar.h>
+#include <sys/sysctl.h>
 
 #include <cam/cam.h>
 #include <cam/cam_ccb.h>