Safer rm, more quickly

Giorgos Keramidas, after reading an article about how rm -rf / (i.e. accidentally deleting your operating system) is avoided by Sun, suggested on the hackers@freebsd.org mailing list some changes to protect from that. An extensive discussion (bikeshed) ensued. See “Protection from the dreaded “rm -fr /” thread on the former link, if you are curious. It’s still not resolved.

On the other hand, this has been quickly fixed in DragonFly, without changing the basic function of rm. New installs will have this safer behavior by default, though the old unsafe setup can be restored if desired.

Superspeed change

Joerg Sonnenberger has added a new timer method, for those who are seeing the “high-speed clock” problem:

“Add a new option “TIMER_USE_1″, which allows switching the primary heartbeat from i8254 timer 2 to timer 1. This also reactivates the console beep if TIMER_USE_1 is active.”

It’s “OPTIONS TIMER_USE_1” in your kernel config, if you want to build a kernel that uses this.

Finding the BGL

ps (from Matthew Dillon’s recent change) is now able to show which processes are and are not holding the “Big Giant Lock”, a symptom of multiprocessor use inherited from FreeBSD.

If you aren’t familiar with the BGL, Greg Lehey wrote a good explanation in Daemonnews. (look for the section labeled “The SMP Problem”)