On Fri, 11 Nov 2005, kama wrote: > Just upgraded from 5.4 to 6.0 and hyperthreading stoped working. > Everything looks ok, but it doesn't use two of the logical CPU's.
This is disabled by default due to a information-leak vulnerability across the hyperthreaded cores. The details from the release notes: Because of an information disclosure vulnerability on processors using Hyper-Threading Technology (HTT), the machdep.hyperthreading_allowed sysctl variable has been added. It defaults to 1 (HTT enabled) on FreeBSD CURRENT, and 0 (HTT disabled) on the 4-STABLE and 5-STABLE development branches and supported security fix branches. More information can be found in security advisory FreeBSD-SA-05:09.htt. [MERGED] If you don't care about this, add machdep.hyperthreading_allowed="1" to /boot/loader.conf and reboot. > One other thing is when I try to switch off hyperthreading in BIOS, it > will hang at bootup when it are settling the scsi drives. After awhile it > will give me scsi timeouts. This only happens when I have two cpu enabled > and hyperthreading off. If I disable one cpu w ht off it will boot wo > problems, or two cpus w ht. But booting with ht + two cpu's gives me the > other problem. Sounds like the BIOS is not rerouting the interrupts correctly. Check for a BIOS update. -- Doug White | FreeBSD: The Power to Serve [EMAIL PROTECTED] | www.FreeBSD.org _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "[EMAIL PROTECTED]"
