Linus Torvalds Calls Linux Patch for Intel CPUs “Complete and Utter Garbage”

The patch submitted by David Woodhouse, ex-Intel kernel engineer that now works for Amazon described a so-called new feature for Intel processors to address Indirect Branch Restricted Speculation (IBRS) by creating macros that would restrict or unrestrict Indirect Branch Speculation based on if the Intel CPU will advertise “I am able to be not broken.” The “x86/enter: Create macros to restrict/unrestrict Indirect Branch Speculation” feature implies that the IBRS (Indirect Branch Restricted Speculation) bit needed to be set at boot time to “ask” the processor not to be broken. Linus Torvalds immediately reacted to the patch calling it “complete and utter garbage” despite the developer’s efforts to explain why he implemented the nasty hack.