Sandsifter: find undocumented instructions and bugs on x86 CPU
tl'dr of the slides:    Found on one processor... instruction
    Single malformed instruction in ring 3 locks
    Tested on 2 Windows kernels, 3 Linux kernels
    Kernel debugging, serial I/O, interrupt analysis seem to confirm
    Unfortunately, not finished with responsible disclosure
    No details available [yet] on chip, vendor, or instructions

He's found a new f00f bug, winter 2017 is going to be interesting :)