maybe these nuggets of knowledge will help someone…

I spent almost an hour yesterday investigating why FreeBSD 9.1 hangs 1-2 minutes after bootup on Sun x4100.
Finally I noticed that powerd always came up in top right before the hang which led me to disabling ACPI throttle by adding hint.acpi_throttle.0.disabled=1 to the /boot/loader.conf file.
Everything has worked fine since that.
I haven’t tried any other FreeBSD versions on that hardware so I have no idea if the problem is present with the older versions of the OS too.

Just out of curiosity I measured power consumption of this machine, here are the results:

• turned off, PSU fans spinning: ~35W
• cold start, fans running in high speed for about a minute before BIOS appears: ~200W
• FreeBSD idling, 4 cores running at 1Ghz: ~150W
• FreeBSD under full load (buildworld -j16), 4 cores running at 2.2Ghz: ~250W

On a completely unrelated note, I spent some time configuring IPv6 on a dedicated server rented through Hetzner’s serverbidding process.
All the tutorials talking about Hetzner specific FreeBSD IPv6 configuration seemed to be rather complicated.

Well it seems Hetzner has since made their IPv6 network setup simpler and default routers are now always at link local address fe80::1 so all that I had to add to the /etc/rc.conf to get things working under FreeBSD 9.0 is something along the lines of:

ipv6_enable="YES"
ipv6_default_interface="re0"
ipv6_defaultrouter="fe80::1%re0"
ipv6_ifconfig_re0="2001:db8:a0:80a1::2 prefixlen 64"