--- xnu/xnu-2050.9.2/iokit/Kernel/IOBufferMemoryDescriptor.cpp
+++ xnu/xnu-1504.15.3/iokit/Kernel/IOBufferMemoryDescriptor.cpp
@@ -99,11 +99,19 @@
 	return (false);
     _ranges.v64->address = 0;
     _ranges.v64->length  = 0;
-	//  make sure super::free doesn't dealloc _ranges before super::init
-	_flags = kIOMemoryAsReference;
 
     // Grab IOMD bits from the Buffer MD options
     iomdOptions  |= (options & kIOBufferDescriptorMemoryFlags);
+
+#if 0
+    // workarounds-
+    if ((options & kIOMemoryPhysicallyContiguous) || ((capacity == 0x1000) && (inTask == kernel_task))
+      && !physicalMask)
+    {
+	highestMask = physicalMask = 0xFFFFF000;
+    }
+    //-
+#endif
 
     if (physicalMask && (alignment <= 1))
     {
@@ -148,10 +156,6 @@
 
 	case kIOMapCopybackCache:
 	    SET_MAP_MEM(MAP_MEM_COPYBACK, memEntryCacheMode);
-	    break;
-
-	case kIOMapCopybackInnerCache:
-	    SET_MAP_MEM(MAP_MEM_INNERWBACK, memEntryCacheMode);
 	    break;
 
 	case kIOMapDefaultCache: