Linux Kernel Set To Finally Retire AMD 3DNow!

Queued up as part of the x86/core changes intended for the Linux 5.17 cycle is dropping of the AMD 3DNow! code within the kernel. While 3DNow! brings back fond memories from the days of AMD's K6 and early Athlon processors, AMD deprecated the instructions a decade ago and no longer found in newer processors. Removing of the 3DNow! kernel code is being done as part of some code improvements.

Hitting tip's x86/core branch is this commit dropping the 3DNow! code from the kernel. 3DNow! built upon MMX instruction set to offer faster performance for vector processing of floating point data. But 3DNow! ultimately didn't see too much adoption amid Intel's successful SSE introduction.

The X86_USE_3DNOW option is removed that defaulted to on for kernel builds targeting now-old processors like the Geode LX, K7, and Cyrix III. This X86_USE_3DNOW option enabled the 3DNow! helper library code in the kernel and allowed for MMX 3DNow! accelerated memcpy usage and accelerated clearing and copying of pages.

Removing this 3DNow! support from the kernel allows freeing around 500 lines of code that had been in the kernel for over two decades. 3DNow! was found in AMD processors from the K6-2 up until Bulldozer where it was retired. Now it's time to let the kernel code go come 2022 with the Linux 5.17 cycle.