--- xnu/xnu-3248.50.21/iokit/Kernel/IOStartIOKit.cpp
+++ xnu/xnu-4570.71.2/iokit/Kernel/IOStartIOKit.cpp
@@ -43,8 +43,8 @@
 #include <IOKit/IOStatisticsPrivate.h>
 #include <IOKit/IOKitKeysPrivate.h>
 #include <IOKit/IOInterruptAccountingPrivate.h>
-
 #include <IOKit/assert.h>
+#include <sys/conf.h>
 
 #include "IOKitKernelInternal.h"
 
@@ -52,6 +52,10 @@
 OSSet *          gIORemoveOnReadProperties;
 
 extern "C" {
+
+void StartIOKit( void * p1, void * p2, void * p3, void * p4 );
+void IORegistrySetOSBuildVersion(char * build_version);
+void IORecordProgressBackbuffer(void * buffer, size_t size, uint32_t theme);
 
 extern void OSlibkernInit (void);
 
@@ -73,7 +77,7 @@
 		IOService::resourceMatching("IONVRAM"), &t );
 #endif
 
-    clock_initialize_calendar();
+	clock_initialize_calendar();
 }
 
 void iokit_post_constructor_init(void)
@@ -107,9 +111,6 @@
 	obj->release();
     }
 }
-
-// From <osfmk/kern/debug.c>
-extern int debug_mode;
 
 /*****
  * Pointer into bootstrap KLD segment for functions never used past startup.
@@ -133,10 +134,6 @@
     // Compat for boot-args
     gIOKitTrace |= (gIOKitDebug & kIOTraceCompatBootArgs);
 	
-    // Check for the log synchronous bit set in io
-    if (gIOKitDebug & kIOLogSynchronous)
-        debug_mode = true;
-
     if( PE_parse_boot_argn( "pmtimeout", &debugFlags, sizeof (debugFlags) ))
         gCanSleepTimeout = debugFlags;
     //
@@ -148,6 +145,7 @@
     //
     IOLibInit(); 
     OSlibkernInit();
+    devsw_init();
 
     gIOProgressBackbufferKey  = OSSymbol::withCStringNoCopy(kIOProgressBackbufferKey);
     gIORemoveOnReadProperties = OSSet::withObjects((const OSObject **) &gIOProgressBackbufferKey, 1);