--- xnu/xnu-12377.101.15/iokit/Kernel/IOStartIOKit.cpp
+++ xnu/xnu-4903.270.47/iokit/Kernel/IOStartIOKit.cpp
@@ -28,7 +28,6 @@
 
 #include <libkern/c++/OSUnserialize.h>
 #include <libkern/c++/OSKext.h>
-#include <libkern/section_keywords.h>
 #include <libkern/version.h>
 #include <IOKit/IORegistryEntry.h>
 #include <IOKit/IODeviceTreeSupport.h>
@@ -36,7 +35,6 @@
 #include <IOKit/IOUserClient.h>
 #include <IOKit/IOMemoryDescriptor.h>
 #include <IOKit/IOPlatformExpert.h>
-#include <IOKit/IOKernelReporters.h>
 #include <IOKit/IOLib.h>
 #include <IOKit/IOKitKeys.h>
 #include <IOKit/IOKitDebug.h>
@@ -54,9 +52,7 @@
 OSSet *          gIORemoveOnReadProperties;
 
 extern "C" {
-void InitIOKit(void *dtTop);
-void ConfigureIOKit(void);
-void StartIOKitMatching(void);
+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);
 
@@ -64,8 +60,6 @@
 
 void iokit_post_constructor_init(void);
 
-SECURITY_READ_ONLY_LATE(static IOPlatformExpertDevice*) gRootNub;
-
 #include <kern/clock.h>
 #include <sys/time.h>
 
@@ -76,7 +70,6 @@
 
 	t.tv_sec = 30;
 	t.tv_nsec = 0;
-
 	IOService::waitForService(
 		IOService::resourceMatching("IORTC"), &t );
 #if defined(__i386__) || defined(__x86_64__)
@@ -94,7 +87,6 @@
 	OSObject *                  obj;
 
 	IOCPUInitialize();
-	IOPlatformActionsInitialize();
 	root = IORegistryEntry::initialize();
 	assert( root );
 	IOService::initialize();
@@ -104,7 +96,6 @@
 	IOUserClient::initialize();
 	IOMemoryDescriptor::initialize();
 	IORootParent::initialize();
-	IOReporter::initialize();
 
 	// Initializes IOPMinformeeList class-wide shared lock
 	IOPMinformeeList::getSharedRecursiveLock();
@@ -125,14 +116,33 @@
 /*****
  * Pointer into bootstrap KLD segment for functions never used past startup.
  */
-void (*record_startup_extensions_function)(void) = NULL;
-
-void
-InitIOKit(void *dtTop)
-{
+void (*record_startup_extensions_function)(void) = 0;
+
+void
+StartIOKit( void * p1, void * p2, void * p3, void * p4 )
+{
+	IOPlatformExpertDevice *    rootNub;
+	int                         debugFlags;
+
+	if (PE_parse_boot_argn( "io", &debugFlags, sizeof(debugFlags))) {
+		gIOKitDebug = debugFlags;
+	}
+#if DEVELOPMENT || DEBUG
+	else {
+		gIOKitDebug |= kIOWaitQuietPanics;
+	}
+#endif /* DEVELOPMENT || DEBUG */
+
+	if (PE_parse_boot_argn( "iotrace", &debugFlags, sizeof(debugFlags))) {
+		gIOKitTrace = debugFlags;
+	}
+
 	// Compat for boot-args
 	gIOKitTrace |= (gIOKitDebug & kIOTraceCompatBootArgs);
 
+	if (PE_parse_boot_argn( "pmtimeout", &debugFlags, sizeof(debugFlags))) {
+		gCanSleepTimeout = debugFlags;
+	}
 	//
 	// Have to start IOKit environment before we attempt to start
 	// the C++ runtime environment.  At some stage we have to clean up
@@ -142,58 +152,36 @@
 	//
 	IOLibInit();
 	OSlibkernInit();
-	IOMachPortInitialize();
+	devsw_init();
 
 	gIOProgressBackbufferKey  = OSSymbol::withCStringNoCopy(kIOProgressBackbufferKey);
 	gIORemoveOnReadProperties = OSSet::withObjects((const OSObject **) &gIOProgressBackbufferKey, 1);
 
 	interruptAccountingInit();
 
-	gRootNub = new IOPlatformExpertDevice;
-	if (__improbable(gRootNub == NULL)) {
-		panic("Failed to allocate IOKit root nub");
-	}
-	bool ok = gRootNub->init(dtTop);
-	if (__improbable(!ok)) {
-		panic("Failed to initialize IOKit root nub");
-	}
-	gRootNub->attach(NULL);
-
-	/* If the bootstrap segment set up a function to record startup
-	 * extensions, call it now.
-	 */
-	if (record_startup_extensions_function) {
-		record_startup_extensions_function();
-	}
-}
-
-void
-ConfigureIOKit(void)
-{
-	assert(gRootNub != NULL);
-	gRootNub->configureDefaults();
-}
-
-void
-StartIOKitMatching(void)
-{
-	SOCD_TRACE_XNU(START_IOKIT, SOCD_TRACE_MODE_NONE);
-	assert(gRootNub != NULL);
-	bool ok = gRootNub->startIOServiceMatching();
-	if (__improbable(!ok)) {
-		panic("Failed to start IOService matching");
-	}
+	rootNub = new IOPlatformExpertDevice;
+
+	if (rootNub && rootNub->initWithArgs( p1, p2, p3, p4)) {
+		rootNub->attach( 0 );
+
+		/* If the bootstrap segment set up a function to record startup
+		 * extensions, call it now.
+		 */
+		if (record_startup_extensions_function) {
+			record_startup_extensions_function();
+		}
+
+		rootNub->registerService();
 
 #if !NO_KEXTD
-	if (OSKext::iokitDaemonAvailable()) {
-		/* Add a busy count to keep the registry busy until the IOKit daemon has
-		 * completely finished launching. This is decremented when the IOKit daemon
+		/* Add a busy count to keep the registry busy until kextd has
+		 * completely finished launching. This is decremented when kextd
 		 * messages the kernel after the in-kernel linker has been
 		 * removed and personalities have been sent.
 		 */
 		IOService::getServiceRoot()->adjustBusy(1);
-	}
 #endif
+	}
 }
 
 void
@@ -216,12 +204,8 @@
 IORecordProgressBackbuffer(void * buffer, size_t size, uint32_t theme)
 {
 	IORegistryEntry * chosen;
-
-	if (((unsigned int) size) != size) {
-		return;
-	}
 	if ((chosen = IORegistryEntry::fromPath(kIODeviceTreePlane ":/chosen"))) {
-		chosen->setProperty(kIOProgressBackbufferKey, buffer, (unsigned int) size);
+		chosen->setProperty(kIOProgressBackbufferKey, buffer, size);
 		chosen->setProperty(kIOProgressColorThemeKey, theme, 32);
 
 		chosen->release();