How much memory can a 32 bit process access on a 64 bit operating system?

windows memory wow64
jjxtra picture jjxtra · Mar 12, 2009 · Viewed 135.7k times · Source

On Windows, under normal circumstances a 32 bit process can only access 2GB of RAM (or 3GB with a special switch in the boot.ini file). When running a 32 bit process on a 64 bit operating system, how much memory is available? Are there any special switches or settings that can change this?

Answer

Michael picture Michael · Mar 12, 2009

2 GB by default. If the application is large address space aware (linked with /LARGEADDRESSAWARE), it gets 4 GB (not 3 GB, see http://msdn.microsoft.com/en-us/library/aa366778.aspx)

They're still limited to 2 GB since many application depends on the top bit of pointers to be zero.

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