supports All Cyrix CPUs, IBM Blue Lightning CPU and NexGen (now AMD)
Nx586 CPU, and initialize special registers of Cyrix CPU and msr of
IBM Blue Lightning CPU.
If revision of Cyrix 6x86 CPU < 2.7, CPU cache is enabled in
write-through mode. This can be disabled by kernel configuration
options.
Reviewed by: Bruce Evans <bde@freebsd.org> and
Jordan K. Hubbard <jkh@freebsd.org>