Since i recently moved into my own flat and now have to pay for the electricity i consume i wanted to get Suspend-to-ram working (why not suspend-to-disk you might ask. well, that would be the next step ;). One of my most frequented websites linux.com posted a short intro and a script to do just that. Unforunately, echo -n “mem” > /sys/power/state always quit with an error about a not-exisiting device. So i started looking through my kernel-config for acpi-sleep-support. Funny thing was it showed up nowhere. Even more funny was that with the new 2.6.21.1 and without one of my old .configs in place, it showed up under “ACPI Support”. Long story short (imagine me searching for about half an hour…), you have to enable “[*] Support for hot-pluggable CPUs (EXPERIMENTAL)” (in “Processor type and features”) in order to see the ACPI-Sleep options… don’t ask. It works fine now, it is really fast, and when i resume everything works again (sound, graphics, network, vpnc). Now, on with the suspend-to-disk ;)