Better spurious interrupt handling

src/kernel/apic.cpp

@@ -62,7 +62,7 @@ lapic::calibrate_timer()
 	outb(0x43, command);
 
 	const uint32_t initial = -1u;
-	enable_timer_internal(isr::isrIgnore0, 1, initial, false);
+	enable_timer_internal(isr::isrSpurious, 1, initial, false);
 
 	const int iterations = 5;
 	for (int i=0; i<iterations; ++i) {

src/kernel/interrupt_isrs.inc

@@ -240,10 +240,10 @@ IRQ (0xdf, 0xbf, irqBF)
 ISR (0xe0, isrTimer)
 ISR (0xe1, isrLINT0)
 ISR (0xe2, isrLINT1)
-ISR (0xe3, isrSpurious)
 ISR (0xe4, isrAssert)
 
 UISR(0xee, isrSyscall)
+ISR (0xef, isrSpurious)
 
 ISR (0xf0, isrIgnore0)
 ISR (0xf1, isrIgnore1)

src/kernel/interrupts.cpp

@@ -204,6 +204,10 @@ isr_handler(addr_t return_rsp, cpu_state regs)
 		}
 		break;
 
+	case isr::isrSpurious:
+		// No EOI for the spurious interrupt
+		return return_rsp;
+
 	case isr::isrIgnore0:
 	case isr::isrIgnore1:
 	case isr::isrIgnore2: