On x86-64 linux you can `mmap` with the `MAP_32BIT` flag which gives you memory in the 32 bit address space. As 32-bit writes to registers get implicitly zero-e

On x86-64 linux you can `mmap` with the `MAP_32BIT` flag which gives you memory in the 32 bit address space. As 32-bit writes to registers get implicitly zero-extended you can store and load those pointers in 32 bit without any performance drawbacks. This all is a bit hackish. With the x32 abi you can simply have 32 bit pointers everywhere.