[luser001]

I would run a 32-bit OS (even if the hardware supported 64-bit) if I wanted to squeeze every last bit of usable memory out of a VPS.

[derleth]

This sounds like precisely the use-case for x32: Running userland programs that only use 32-bit pointers on x86-64 bit hardware in 64-bit mode; you only get to address 4GB of RAM, but your pointers fit two to a register and you have all the x86-64 registers, opcodes, and special hardware.

Sadly, it isn't here yet.

https://sites.google.com/site/x32abi/

http://en.wikipedia.org/wiki/X32_ABI

(To forestall the obvious objection: No, there's no way Torvalds will allow this to re-introduce the 2038 Problem into a new ABI. None.)

[Aissen]

x32 has been accepted(and merged) for Linux 3.4. Kernel support is here, now it's userspace's turn.