bit 10 is the old bit for MTRR (presumably this changed, an older P5 I
have has got it, the newer cpus have the new MTRR bit set)
bit 11 is SEP (fast syscalls), bit 23 is MMX
Fill in the other reserved ones with a stub so that we can see them if
they turn up.
Obtained from: Intel AP-485 rev.06
2895de58f2