Linux 7.5 to retire final MMX optimizations, closing the book on 30 years of Pentium-era code
The upcoming Linux kernel will strip out the last software RAID optimizations built for Intel's 1997 MultiMedia eXtensions instruction set, marking the end of support for a technology that defined the Pentium generation.
When Intel rolled out MMX in 1997, the MultiMedia eXtension instruction set promised to accelerate multimedia workloads on personal computers equipped with CD-ROM drives. Three decades later, Linux is preparing to sever its final ties to the aging technology.
Developers working on the Linux kernel are moving forward with a patch that will eliminate the last vestiges of MMX-optimized code from the operating system. The change is slated to land in Linux 7.5, which is expected to ship in 2027, according to reporting from Phoronix. The removal will affect the software RAID XOR code, one of the few remaining components still carrying MMX optimizations.
In practical terms, the impact will be minimal. Few systems running cutting-edge kernels in 2026 will rely on Pentium MMX or Pentium II processors. The bulk of MMX-optimized code had already vanished from Linux roughly five years prior, when memory management routines built around the instruction set were stripped out. Users determined to keep aging Pentium hardware operational will retain the ability to deploy software RAID, though they will forfeit the performance advantage that MMX acceleration once provided.