BOOL XMemAllocatePhysicalPages(  
         ULONGLONG XMemFlags,  
         PULONG_PTR NumberOfPages,  
         PULONG_PTR PageArray  
)  

ULONG_PTR PageArray[64];
ULONG_PTR PageCount = RTL_NUMBER_OF(PageArray);
XMemAllocatePhysicalPages(XMEM_2MB_CLUSTERS, &PageCount, PageArray);

// Allocate 4MB of reserved space as both 64KB page sizes and 2MB page sizes
PVOID RWAddress = XMemVirtualAlloc(NULL,
    4 * 1024 * 1024,
    MEM_64K_PAGES | MEM_RESERVE,
    XMEM_CPU | XMEM_MAPPABLE,
    PAGE_READWRITE);

PVOID ROAddress = XMemVirtualAlloc(NULL,
    4 * 1024 * 1024,
    MEM_2MB_PAGES | MEM_RESERVE,
    XMEM_CPU | XMEM_MAPPABLE,
    PAGE_READONLY);

// Map the physical pages into the 64k address reservation
XMemMapPhysicalPages(RWAddress, PageCount, PageArray);

// Map the physical pages into the 2MB address reservation
// Use only the first physical page of each 2MB run
ULONG_PTR PageArray2MB[2];
PageArray2MB[0] = PageArray[0];
PageArray2MB[1] = PageArray[32];
XMemMapPhysicalPages(ROAddress, 2, PageArray2MB);

memset(RWAddress, 0x17, 4 * 1024 * 1024);
assert (memcmp(RWAddress, ROAddress, 4 * 1024 * 1024)==0);

// Unmap the regions, the address reservation is preserved
XMemMapPhysicalPages(ROAddress, 2, NULL);
XMemMapPhysicalPages(RWAddress, 64, NULL);

// Release the physical pages back to the MM
XMemFreePhysicalPages(PageCount, PageArray);

// Release the two reserved address regions
VirtualFree(RWAddress, 0, MEM_RELEASE);
VirtualFree(ROAddress, 0, MEM_RELEASE);