K 10
svn:author
V 8
cperciva
K 8
svn:date
V 27
2007-11-28T23:24:07.000000Z
K 7
svn:log
V 823
Back out previous commit; i.e., turn hyperthreading back on by default.

Newer Intel processors have better hyperthreading implementations than
the original ones, and FreeBSD's SMP and scheduler code has greatly
improved between 6.x and 7.x; so hyperthreading now provides a
non-trivial performance win.

Note that security issues involving shared caches and other
microarchitectural features (e.g., dynamic branch prediction tables)
still exist; consequently, it is recommended that hyperthreading be
turned off on systems with untrusted local users.  This can be
performed by setting machdep.hyperthreading_allowed=0 in
/boot/loader.conf.

Hyperthreading will continue to be disabled by default on FreeBSD 6.x.

Requested by:	core
Approved by:	re (kensmith)
Security:	See FreeBSD-SA-05:09.htt for background information.

END