title: Using a 64 bit driver in a 32 bit program. Windows
body: <p>This is only a half-way programming question. First of all I have a PCI-Express card and 32/64 bit drivers. The target operating system has to be a Windows 64 bit system. I read that under Vista64 all drivers have to be certified 64 bit drivers. Is this a general restriction under 64 bit operating systems and does this also apply to "XP 64" or any Linux system?</p>
  
  <p>So for simplicity let's say I use a 64 bit driver for my PCIe card under Vista64 and have a bunch of 64 bit DLLs to use the cards functionality. On the other side there's a large, legacy 32 bit exe program which needs to use the PCIe device. Converting the program to 64 bit would be a really huge effort. </p>
  
  <p>So what can be done to bring that 32 bit program and the 64 bit driver together? I read that mixing 32/64 bit binaries and DLLs is not possible at all but this is hard to believe for me. I'm sure you can print out a document under Vista64 from within a 32 bit app and Windows will somehow wrap this around to a 64 bit printer driver. </p>