Index: /trunk/src/VBox/Devices/Bus/DevPciIch9.cpp
===================================================================
--- /trunk/src/VBox/Devices/Bus/DevPciIch9.cpp	(revision 64700)
+++ /trunk/src/VBox/Devices/Bus/DevPciIch9.cpp	(revision 64701)
@@ -1707,5 +1707,5 @@
     }
 
-    uint8_t uMaxSubNum = 0;
+    uint8_t uMaxSubNum = pBus->iBus;
     for (uint32_t iBridge = 0; iBridge < pBus->cBridges; iBridge++)
     {
@@ -1715,5 +1715,5 @@
         PDEVPCIBUS pChildBus = PDMINS_2_DATA(pBridge->Int.s.CTX_SUFF(pDevIns), PDEVPCIBUS);
         uint8_t uMaxChildSubBus = ich9pciBiosInitBridgeTopology(pPciRoot, pChildBus, uBusSecondary, pChildBus->iBus);
-        uMaxSubNum = RT_MAX(uMaxSubNum, RT_MAX(uMaxChildSubBus, pChildBus->iBus));
+        uMaxSubNum = RT_MAX(uMaxSubNum, uMaxChildSubBus);
     }
     PCIDevSetByte(pBridgeDev, VBOX_PCI_SUBORDINATE_BUS, uMaxSubNum);