Index: head/sys/arm64/arm64/gic_v3_acpi.c
===================================================================
--- head/sys/arm64/arm64/gic_v3_acpi.c
+++ head/sys/arm64/arm64/gic_v3_acpi.c
@@ -305,6 +305,8 @@
 	struct gic_v3_acpi_devinfo *di;
 	struct gic_v3_softc *sc;
 	device_t child, dev;
+	u_int xref;
+	int err, pxm;
 
 	if (entry->Type == ACPI_MADT_TYPE_GENERIC_TRANSLATOR) {
 		/* We have an ITS, add it as a child */
@@ -321,7 +323,14 @@
 		resource_list_add(&di->di_rl, SYS_RES_MEMORY, 0,
 		    gict->BaseAddress, gict->BaseAddress + 128 * 1024 - 1,
 		    128 * 1024);
-		di->di_gic_dinfo.gic_domain = -1;
+		err = acpi_iort_its_lookup(gict->TranslationId, &xref, &pxm);
+		if (err == 0) {
+			di->di_gic_dinfo.gic_domain = pxm;
+			di->di_gic_dinfo.msi_xref = xref;
+		} else {
+			di->di_gic_dinfo.gic_domain = -1;
+			di->di_gic_dinfo.msi_xref = ACPI_MSI_XREF;
+		}
 		sc->gic_nchildren++;
 		device_set_ivars(child, di);
 	}
Index: head/sys/arm64/arm64/gic_v3_var.h
===================================================================
--- head/sys/arm64/arm64/gic_v3_var.h
+++ head/sys/arm64/arm64/gic_v3_var.h
@@ -87,6 +87,7 @@
 
 struct gic_v3_devinfo {
 	int gic_domain;
+	int msi_xref;
 };
 
 #define GIC_INTR_ISRC(sc, irq)	(&sc->gic_irqs[irq].gi_isrc)
Index: head/sys/arm64/arm64/gicv3_its.c
===================================================================
--- head/sys/arm64/arm64/gicv3_its.c
+++ head/sys/arm64/arm64/gicv3_its.c
@@ -1722,6 +1722,7 @@
 gicv3_its_acpi_attach(device_t dev)
 {
 	struct gicv3_its_softc *sc;
+	struct gic_v3_devinfo *di;
 	int err;
 
 	sc = device_get_softc(dev);
@@ -1729,13 +1730,13 @@
 	if (err != 0)
 		return (err);
 
-	sc->sc_pic = intr_pic_register(dev,
-	    device_get_unit(dev) + ACPI_MSI_XREF);
+	di = device_get_ivars(dev);
+	sc->sc_pic = intr_pic_register(dev, di->msi_xref);
 	intr_pic_add_handler(device_get_parent(dev), sc->sc_pic,
 	    gicv3_its_intr, sc, sc->sc_irq_base, sc->sc_irq_length);
 
 	/* Register this device to handle MSI interrupts */
-	intr_msi_register(dev, device_get_unit(dev) + ACPI_MSI_XREF);
+	intr_msi_register(dev, di->msi_xref);
 
 	return (0);
 }