To rephrase your question, are there any Long Mode user space changes? Skimming Intel's spec ( https://cdrdv2.intel.com/v1/dl/getContent/776648 https://cdrdv2.

To rephrase your question, are there any Long Mode user space changes? Skimming Intel's spec ( https://cdrdv2.intel.com/v1/dl/getContent/776648 https://cdrdv2.intel.com/v1/dl/getContent/776648 ), the X86S looks really risk-adverse towards changing Long Mode user space. I don't recognize any changes offhand, but my knowledge of x86 legacy is pretty limited (and will hopefully be obsolete soon).