[HALX86:DMA] HACK: Avoid excessive stack usage

CORE-17256

Author: disean

hal/halx86/generic/dma.c

@@ -77,7 +77,7 @@
 #define NDEBUG
 #include <debug.h>
 
-#define MAX_SG_ELEMENTS 0x10
+#define MAX_SG_ELEMENTS 0x20
 
 #ifndef _MINIHAL_
 static KEVENT HalpDmaLock;
@@ -993,13 +993,16 @@ HalpScatterGatherAdapterControl(IN PDEVICE_OBJECT DeviceObject,
 	PSCATTER_GATHER_CONTEXT AdapterControlContext = Context;
 	PADAPTER_OBJECT AdapterObject = AdapterControlContext->AdapterObject;
 	PSCATTER_GATHER_LIST ScatterGatherList;
-	SCATTER_GATHER_ELEMENT TempElements[MAX_SG_ELEMENTS];
+	PSCATTER_GATHER_ELEMENT TempElements;
 	ULONG ElementCount = 0, RemainingLength = AdapterControlContext->Length;
 	PUCHAR CurrentVa = AdapterControlContext->CurrentVa;
 
 	/* Store the map register base for later in HalPutScatterGatherList */
 	AdapterControlContext->MapRegisterBase = MapRegisterBase;
 
+	TempElements = ExAllocatePoolZero(NonPagedPool, sizeof(*TempElements) * MAX_SG_ELEMENTS, TAG_DMA);
+	ASSERT(TempElements);
+
 	while (RemainingLength > 0 && ElementCount < MAX_SG_ELEMENTS)
 	{
 	    TempElements[ElementCount].Length = RemainingLength;
@@ -1039,6 +1042,8 @@ HalpScatterGatherAdapterControl(IN PDEVICE_OBJECT DeviceObject,
 	              TempElements,
 				  sizeof(SCATTER_GATHER_ELEMENT) * ElementCount);
 
+	ExFreePoolWithTag(TempElements, TAG_DMA);
+
 	DPRINT("Initiating S/G DMA with %d element(s)\n", ElementCount);
 
 	AdapterControlContext->AdapterListControlRoutine(DeviceObject,