GoKawiilLinux 7.5 to drop final MMX-optimized code from RAID XOR routines
A patch set to merge into mainline Linux 7.5, expected in 2027, will remove the kernel's last MMX-optimized code, located in the software RAID XOR routines, according to Phoronix. The change strips over 800 lines of code down to just 12 lines. Most other MMX-optimized code, including memory management routines, was already removed from Linux about five years ago.
GoKawiil's interpretation of the reporting above, not reported fact.
The removal reflects routine kernel maintenance rather than any functional loss for current users, since Intel's MMX instructions date to 1997-era Pentium chips that are vanishingly rare in modern computing. Users still running MMX-era hardware will be able to use software RAID, but without the MMX-accelerated fast path, suggesting negligible real-world impact. The change mainly illustrates how Linux periodically sheds legacy code to reduce maintenance burden.
- Linux 7.5 will remove the kernel's last remaining MMX-optimized code from software RAID XOR routines.
- The cleanup cuts over 800 lines of code down to just 12 lines.
- MMX, introduced by Intel in 1997, is being phased out of Linux as hardware from that era becomes effectively obsolete.
Source: tomshardware.com — Mark Tyson, 2026-11-08
Published there as: “The end of an era as Linux 7.5 purges the last 30-year-old Intel MMX optimizations from Pentium age”
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