X86: Mask the PIC at startup to avoid a glitch which causes an NMI.

src/dev/x86/i8259.hh

@@ -39,8 +39,6 @@
 namespace X86ISA
 {
 
-class I82094AA;
-
 class I8259 : public BasicPioDevice, public IntDev
 {
   protected:
@@ -94,6 +92,18 @@ class I8259 : public BasicPioDevice, public IntDev
     Tick read(PacketPtr pkt);
     Tick write(PacketPtr pkt);
 
+    void
+    maskAll()
+    {
+        IMR = 0xFF;
+    }
+
+    void
+    unmaskAll()
+    {
+        IMR = 0x00;
+    }
+
     void signalInterrupt(int line);
     void raiseInterruptPin(int number);
     void lowerInterruptPin(int number);

src/dev/x86/pc.cc

@@ -107,6 +107,13 @@ Pc::init()
     entry.vector = 0x30;
     ioApic.writeReg(0x30, entry.bottomDW);
     ioApic.writeReg(0x31, entry.topDW);
+
+    /*
+     * Mask the PICs. I'm presuming the BIOS/bootloader would have cleared
+     * these out and masked them before passing control to the OS.
+     */
+    southBridge->pic1->maskAll();
+    southBridge->pic2->maskAll();
 }
 
 Tick