问题
What is the maximum private memory that a 32 bit process can address on a 64 bit operating system?
回答1:
The limit is 2GB. Please refer to this link for details
回答2:
Generally: same as if it was running on a 32bit OS. It's internal pointers are still 32bit, so only 4G addressable. Same limitations apply with kernel reserved address space, which will depend on the exact OS and its configuration (usually the process will have a total of 2 or 3G to play with).
Edit: the above is actually not correct. It appears to be a 2G / 4G option for win64, see the link posted by Neera.
来源：https://stackoverflow.com/questions/5153560/64-bit-os-32-bit-process