X86: Add a latency that describes how long an interrupt takes to propagate through the IO APIC.

src/dev/x86/I82094AA.py

@@ -38,6 +38,8 @@ class I82094AA(BasicPioDevice):
     pio_latency = Param.Latency('1ns', "Programmed IO latency in simticks")
     pio_addr = Param.Addr("Device address")
     int_port = Port("Port for sending and receiving interrupt messages")
+    int_latency = Param.Latency('1ns', \
+            "Latency for an interrupt to propagate through this device.")
     external_int_pic = Param.I8259(NULL, "External PIC, if any")
 
     def pin(self, line):

src/dev/x86/i82094aa.cc

@@ -36,7 +36,8 @@
 #include "mem/packet_access.hh"
 #include "sim/system.hh"
 
-X86ISA::I82094AA::I82094AA(Params *p) : PioDevice(p), IntDev(this),
+X86ISA::I82094AA::I82094AA(Params *p) : PioDevice(p),
+    IntDev(this, p->int_latency),
     latency(p->pio_latency), pioAddr(p->pio_addr),
     extIntPic(p->external_int_pic), lowestPriorityOffset(0)
 {