Index: ic/nvme.c
===================================================================
RCS file: /cvs/src/sys/dev/ic/nvme.c,v
retrieving revision 1.50
diff -u -p -r1.50 nvme.c
--- ic/nvme.c	20 May 2016 11:11:05 -0000	1.50
+++ ic/nvme.c	25 Oct 2016 05:54:54 -0000
@@ -1277,6 +1277,19 @@ nvme_intr(void *xsc)
 	return (rv);
 }
 
+int
+nvme_intr_intx(void *xsc)
+{
+	struct nvme_softc *sc = xsc;
+	int rv;
+
+	nvme_write4(sc, NVME_INTMS, 1);
+	rv = nvme_intr(sc);
+	nvme_write4(sc, NVME_INTMC, 1);
+
+	return (rv);
+}
+
 struct nvme_dmamem *
 nvme_dmamem_alloc(struct nvme_softc *sc, size_t size)
 {
Index: ic/nvmevar.h
===================================================================
RCS file: /cvs/src/sys/dev/ic/nvmevar.h,v
retrieving revision 1.8
diff -u -p -r1.8 nvmevar.h
--- ic/nvmevar.h	14 Apr 2016 11:18:32 -0000	1.8
+++ ic/nvmevar.h	25 Oct 2016 05:54:54 -0000
@@ -102,5 +102,6 @@ struct nvme_softc {
 int	nvme_attach(struct nvme_softc *);
 int	nvme_activate(struct nvme_softc *, int);
 int	nvme_intr(void *);
+int	nvme_intr_intx(void *);
 
 #define DEVNAME(_sc) ((_sc)->sc_dev.dv_xname)
Index: pci/nvme_pci.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/nvme_pci.c,v
retrieving revision 1.3
diff -u -p -r1.3 nvme_pci.c
--- pci/nvme_pci.c	14 Apr 2016 11:18:32 -0000	1.3
+++ pci/nvme_pci.c	25 Oct 2016 05:54:54 -0000
@@ -81,6 +81,7 @@ nvme_pci_attach(struct device *parent, s
 	struct pci_attach_args *pa = aux;
 	pcireg_t maptype;
 	pci_intr_handle_t ih;
+	int msi = 1;
 
 	psc->psc_pc = pa->pa_pc;
 	sc->sc_dmat = pa->pa_dmat;
@@ -92,13 +93,16 @@ nvme_pci_attach(struct device *parent, s
 		return;
 	}
 
-	if (pci_intr_map_msi(pa, &ih) != 0 && pci_intr_map(pa, &ih) != 0) {
-		printf(": unable to map interrupt\n");
-		goto unmap;
+	if (pci_intr_map_msi(pa, &ih) != 0) {
+		if (pci_intr_map(pa, &ih) != 0) {
+			printf(": unable to map interrupt\n");
+			goto unmap;
+		}
+		msi = 0;
 	}
 
 	sc->sc_ih = pci_intr_establish(pa->pa_pc, ih, IPL_BIO,
-	    nvme_intr, sc, DEVNAME(sc));
+	    msi ? nvme_intr : nvme_intr_intx, sc, DEVNAME(sc));
 	if (sc->sc_ih == NULL) {
 		printf(": unable to establish interrupt\n");
 		goto unmap;