Index: sys/x86/include/apicvar.h
===================================================================
--- sys/x86/include/apicvar.h
+++ sys/x86/include/apicvar.h
@@ -159,10 +159,10 @@
 #define	APIC_BUS_PCI		2
 #define	APIC_BUS_MAX		APIC_BUS_PCI
 
-#define	IRQ_EXTINT		-1
-#define	IRQ_NMI			-2
-#define	IRQ_SMI			-3
-#define	IRQ_DISABLED		-4
+#define	IRQ_EXTINT		((u_int)-1)
+#define	IRQ_NMI			((u_int)-2)
+#define	IRQ_SMI			((u_int)-3)
+#define	IRQ_DISABLED		((u_int)-4)
 
 /*
  * An APIC enumerator is a pseudo bus driver that enumerates APIC's including
@@ -195,7 +195,7 @@
 int	ioapic_disable_pin(void *cookie, u_int pin);
 int	ioapic_get_vector(void *cookie, u_int pin);
 void	ioapic_register(void *cookie);
-int	ioapic_remap_vector(void *cookie, u_int pin, int vector);
+int	ioapic_remap_vector(void *cookie, u_int pin, u_int vector);
 int	ioapic_set_bus(void *cookie, u_int pin, int bus_type);
 int	ioapic_set_extint(void *cookie, u_int pin);
 int	ioapic_set_nmi(void *cookie, u_int pin);
Index: sys/x86/x86/io_apic.c
===================================================================
--- sys/x86/x86/io_apic.c
+++ sys/x86/x86/io_apic.c
@@ -80,7 +80,7 @@
 
 struct ioapic_intsrc {
 	struct intsrc io_intsrc;
-	int io_irq;
+	u_int io_irq;
 	u_int io_intpin:8;
 	u_int io_vector:8;
 	u_int io_cpu;
@@ -256,7 +256,7 @@
 		printf("SMI");
 		break;
 	default:
-		printf("%s IRQ %d", ioapic_bus_string(intpin->io_bus),
+		printf("%s IRQ %u", ioapic_bus_string(intpin->io_bus),
 		    intpin->io_irq);
 	}
 }
@@ -324,7 +324,7 @@
 	 * been enabled yet, just ensure that the pin is masked.
 	 */
 	mtx_assert(&icu_lock, MA_OWNED);
-	if (intpin->io_irq == IRQ_DISABLED || (intpin->io_irq >= 0 &&
+	if (intpin->io_irq == IRQ_DISABLED || (intpin->io_irq < num_io_irqs &&
 	    intpin->io_vector == 0)) {
 		low = ioapic_read(io->io_addr,
 		    IOAPIC_REDTBL_LO(intpin->io_intpin));
@@ -506,7 +506,7 @@
 
 	if (intpin->io_vector == 0)
 		if (ioapic_assign_cpu(isrc, intr_next_cpu(isrc->is_domain)) != 0)
-			panic("Couldn't find an APIC vector for IRQ %d",
+			panic("Couldn't find an APIC vector for IRQ %u",
 			    intpin->io_irq);
 	apic_enable_vector(intpin->io_cpu, intpin->io_vector);
 }
@@ -756,14 +756,14 @@
 }
 
 int
-ioapic_remap_vector(void *cookie, u_int pin, int vector)
+ioapic_remap_vector(void *cookie, u_int pin, u_int vector)
 {
 	struct ioapic *io;
 
 	io = (struct ioapic *)cookie;
-	if (pin >= io->io_numintr || vector < 0)
+	if (pin >= io->io_numintr || vector >= num_io_irqs)
 		return (EINVAL);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	io->io_pins[pin].io_irq = vector;
 	if (bootverbose)
@@ -782,7 +782,7 @@
 	io = (struct ioapic *)cookie;
 	if (pin >= io->io_numintr)
 		return (EINVAL);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	if (io->io_pins[pin].io_bus == bus_type)
 		return (0);
@@ -803,7 +803,7 @@
 		return (EINVAL);
 	if (io->io_pins[pin].io_irq == IRQ_NMI)
 		return (0);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	io->io_pins[pin].io_bus = APIC_BUS_UNKNOWN;
 	io->io_pins[pin].io_irq = IRQ_NMI;
@@ -826,7 +826,7 @@
 		return (EINVAL);
 	if (io->io_pins[pin].io_irq == IRQ_SMI)
 		return (0);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	io->io_pins[pin].io_bus = APIC_BUS_UNKNOWN;
 	io->io_pins[pin].io_irq = IRQ_SMI;
@@ -849,7 +849,7 @@
 		return (EINVAL);
 	if (io->io_pins[pin].io_irq == IRQ_EXTINT)
 		return (0);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	io->io_pins[pin].io_bus = APIC_BUS_UNKNOWN;
 	io->io_pins[pin].io_irq = IRQ_EXTINT;
@@ -874,7 +874,7 @@
 	io = (struct ioapic *)cookie;
 	if (pin >= io->io_numintr || pol == INTR_POLARITY_CONFORM)
 		return (EINVAL);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	activehi = (pol == INTR_POLARITY_HIGH);
 	if (io->io_pins[pin].io_activehi == activehi)
@@ -895,7 +895,7 @@
 	io = (struct ioapic *)cookie;
 	if (pin >= io->io_numintr || trigger == INTR_TRIGGER_CONFORM)
 		return (EINVAL);
-	if (io->io_pins[pin].io_irq < 0)
+	if (io->io_pins[pin].io_irq >= num_io_irqs)
 		return (EINVAL);
 	edgetrigger = (trigger == INTR_TRIGGER_EDGE);
 	if (io->io_pins[pin].io_edgetrigger == edgetrigger)
@@ -950,7 +950,7 @@
 
 	io = (struct ioapic *)pic;
 	for (i = 0, pin = io->io_pins; i < io->io_numintr; i++, pin++) {
-		if (pin->io_irq >= 0)
+		if (pin->io_irq < num_io_irqs)
 			intr_register_source(&pin->io_intsrc);
 	}
 }
@@ -1185,7 +1185,7 @@
 }
 
 static u_int
-db_ioapic_read(volatile ioapic_t *apic, int reg)
+db_ioapic_read(volatile ioapic_t *apic, u_int reg)
 {
 
 	apic->ioregsel = reg;