- optimize FPU operations (evaluate x87 stack pointer statically) and
  fix cr0.TS emulation
- fix CCOP optimisation
- fix all remaining thread lock issues (must put TBs in a specific invalid
  state, find a solution for tb_flush()).
- cpu loop optimisation (optimise ret case as the cpu state does not change)
- fix arm fpu rounding (at least for float->integer conversions)
- add IPC syscalls

lower priority:
--------------
- sysenter/sysexit emulation
- SMP support
- finish segment ops (call far, ret far, load_seg suppressed)
- use -msoft-float on ARM
- use kernel traps for unaligned accesses on ARM ?
- handle rare page fault cases (in particular if page fault in heplers or
  in syscall emulation code).
- fix thread stack freeing (use kernel 2.5.x CLONE_CHILD_CLEARTID)
- more syscalls (in particular all 64 bit ones, IPCs, fix 64 bit
  issues, fix 16 bit uid issues)
- use page_unprotect_range in every suitable syscall to handle all
  cases of self modifying code.
- use gcc as a backend to generate better code (easy to do by using
  op-i386.c operations as local inline functions).
- add SSE2/MMX operations