It's not a terrible hack, it's just 32-bit virtual addresses with a larger physical address space. It only caused problems because some kernels used to expect

It's not a terrible hack, it's just 32-bit virtual addresses with a larger physical address space. It only caused problems because some kernels used to expect that all physical memory is mapped at all times (and some hardware could only DMA to 32-bit physical addresses, but that's a problem with 64-bit CPUs as well).