short term:
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+- x86_64: fxsave/fxrestore bugs
+- x86_64: lcall/ljmp intel/amd differences
+- x86_64: cmpxchgl
+- x86_64: cmovl bug
+- x86: monitor invalid
- cycle counter for all archs
- cpu_interrupt() win32/SMP fix
- support variable tsc freq