I am responsible for a database server with very large RAM cache requirements. I have read a lot about Physical Address Extension, a feature of Intel CPUs that is supported by certain Linux kernels and allows an application to make use of up to 64Gb of RAM. However, all of this is theoretical or refers to kernel internals - I have not seen any examples of how this might be used by an application (which needs to map the "high" memory into its own process address space to make it useful).

Can anyone give me any pointers?

Thanks very much.