The x32 effort, an undertaking to provide a native 32-bit ABI for x86_64 on Linux, is finally moving closer to fruition. Peter Anvin has published the set of x32 patches for the Linux kernel that are now up for review and comments.
Peter Anvin and others have long been working towards Linux x32: a native 32-bit ABI for Intel/AMD 64-bit systems so that applications not needing 64-bit pointers can benefit from 64-bit performance while using the memory foot-print of a 32-bit ABI. The Linux x32 ABI support necessitates changes to GNU binutils, the Linux kernel, Glibc, and the compiler (GCC). On Sunday the set of 30 patches touching around 1,000 lines of code was sent off to the kernel mailing list by Anvin.
Benchmarks by the developers have shown that x32 can be about up to 32% faster than x86_64 in some CPU benchmarks. However, in some cases it can also be slightly slower than x86_64 and/or ia32.