Delphi 2007：GlobalMemoryStatus获取总RAM

我需要使用Delphi 2007获取系统的总物理内存.在4GB或更大的系统上使用GlobalMemoryStatus似乎给了我错误.在Delphi 2007中,GlobalMemoryStatusEx不存在,所以我手动将函数调用添加到我的程序中.它正确地返回我的 Windows 7 x64上的内存(8GB)但是在Vista x32系统上它仍然返回一个不正确的值(在这个系统上应该是4GB但是返回2.9GB).
任何想法我可能做错了什么？ GlobalMemoryStatusEx是否适用于较旧的操作系统？

type
  DWORDLONG = UInt64;

  PMemoryStatusEx = ^TMemoryStatusEx;
  TMemoryStatusEx = packed record
    dwLength: DWORD;
    dwMemoryLoad: DWORD;
    ullTotalPhys: DWORDLONG;
    ullAvailPhys: DWORDLONG;
    ullTotalPageFile: DWORDLONG;
    ullAvailPageFile: DWORDLONG;
    ullTotalVirtual: DWORDLONG;
    ullAvailVirtual: DWORDLONG;
    ullAvailExtendedVirtual: DWORDLONG;
  end;

function GlobalMemoryStatusEx(var lpBuffer: TMemoryStatusEx): BOOL; stdcall; external kernel32;

function getmemorysize:word;
var
  memory: TMemoryStatusEx;
begin
  FillChar(memory, SizeOf(memory), 0);
  memory.dwLength := SizeOf(memory);
  GlobalMemoryStatusEx(memory);
  result:=memory.ullTotalPhys div (1024*1024);
end;

这是可以预料的,你没有做错任何事. Windows不会在32位操作系统上报告4GB内存.这是来自MSDN blog article的引用,名为“3GB-not-4GB RAM问题”：

Due to an architectural decision made long ago, if you have 4GB of
physical RAM installed, Windows is only able to report a portion of
the physical 4GB of RAM (ranges from ~2.75GB to 3.5GB depending on the
devices installed, motherboard’s chipset & BIOS).

GlobaMemoryStatusEx应该可以从Windows 2000开始运行(以后的MSDN文档不包括Win2K,但早期的文件有.)