Dell Servers and the Real Time Clock
It seems that Debian gets angry with Dell server hardware. I’ve heard this isn’t a problem on 2.6.10, but cross compiling for 64-bit in a 32-bit userland is annoying, so using Debian’s precompiled em64t-p4-smp kernel is less of a headache. The problem is that when the system boots, it hangs on the setting real time clock step; same thing happens with the saving/setting hardware clock steps. Passing acpi=off to the kernel fixes the problem, but then you don’t get HyperThreading, which is lame when your server has a Xeon or two in it.
The fix seems to be using the “genrtc” module in place of “rtc”. Simply add “genrtc” to your /etc/modules file (I added it to /etc/mkinitrd/modules too for good measure) and reboot without disabling ACPI. If all goes well, you should see double the number of CPUs enabled in your system.
This isn’t a unique problem to me, but you can find more information by searching for “debian dell rtc” on Google. You can also read about how HyperThreading speeds up Linux here: