Index: /trunk/src/VBox/VMM/include/IOMInternal.h
===================================================================
--- /trunk/src/VBox/VMM/include/IOMInternal.h	(revision 45311)
+++ /trunk/src/VBox/VMM/include/IOMInternal.h	(revision 45312)
@@ -19,5 +19,5 @@
 #define ___IOMInternal_h
 
-//#define IOM_WITH_CRIT_SECT_RW
+#define IOM_WITH_CRIT_SECT_RW
 
 #include <VBox/cdefs.h>
@@ -437,5 +437,5 @@
 # define IOM_LOCK_EXCL(a_pVM)                   PDMCritSectRwEnterExcl(&(a_pVM)->iom.s.CritSect, VERR_SEM_BUSY)
 # define IOM_UNLOCK_EXCL(a_pVM)                 do { PDMCritSectRwLeaveExcl(&(a_pVM)->iom.s.CritSect); } while (0)
-# if 0 /* for the time being (the lookup caches needs to be in VMCPU) */
+# if 0 /* (in case needed for debugging) */
 # define IOM_LOCK_SHARED_EX(a_pVM, a_rcBusy)    PDMCritSectRwEnterExcl(&(a_pVM)->iom.s.CritSect, (a_rcBusy))
 # define IOM_UNLOCK_SHARED(a_pVM)               do { PDMCritSectRwLeaveExcl(&(a_pVM)->iom.s.CritSect); } while (0)