AMD (Phenom II x6) Turbo-Core causes random hangs

[Don Rosa]

When AMD TurboCore is enabled in the BIOS any version of FreeBSD I
have tested (8.1R, 8.2-RC3, 3-4months old 9-Current, all AMD64) causes
a hard hang (complete hardware freeze) that I am unable to debug.


I haven't been able to exactly reproduce the hang, but usually the
system freezes after about ~1-2hours of normal usage (eg, compiling
some "light" ports) but I have also noticed that the freeze triggers a
lot faster when playing something in mplayer. (Mplayer rarely lasts
for more than ~40minutes of continuous playback of a simple
low-definition movie).

The freeze is not ports-userland/X related, as it has happened to
hang/freeze in a console pure-install environment by just compiling
system/ports with no extra drivers loaded.

I have experimented with almost all (except TurboCore of course) BIOS
settings with no good results.

FreeBSD-side I have also tried various things:

- Disabling/Enabling powerd
- Disabling acpi_throttle
- Disabling apic clock
- Disabling cpufreq/hwpstate subsystems
- Lowering HZ
- Changing sysctl c-state settings
- Changing timecounters

Of which nothing worked.


Finally turning off TurboCore in the BIOS solves the problem
completely. I have experienced zero freezes with Turbo=off (machine
rock stable), and in sum ~60 freezes with Turbo=on (while I was trying
various things to solve the problem).

Some extra notes:

(all amd64 versions)
Windows7 - no hangs ever with Turbo=on whatever the load/usage
Linux - no hangs ever with Turbo=on whatever the load/usage
OpenBSD 4.8 MP, usage of only 2-3 days, mainly to build stuff, no
hangs with Turbo=on.