Matthew Garrett appears to be having some "fun" looking into how to reboot
x86 hardware. He lists five different mechanisms to reboot 64-bit x86 hardware including: "kbd - reboot via the keyboard controller. The original IBM PC had the CPU reset line tied to the keyboard controller. Writing the appropriate magic value pulses the line and the machine resets. This is all very straightforward, except for the fact that modern machines don't have keyboard controllers (they're actually part of the embedded controller) and even more modern machines don't even pretend to have a keyboard controller. Now, embedded controllers run software. And, as we all know, software is dreadful. But, worse, the software on the embedded controller has been written by BIOS authors. So clearly any pretence that this ever works is some kind of elaborate fiction. Some machines are very picky about hardware being in the exact state that Windows would program. Some machines work 9 times out of 10 and then lock up due to some odd timing issue. And others simply don't work at all. Hurrah!
to post comments)