How to tell whether ECC (memory) is enabled?

[perryh at pluto.rain.com]

Artem Belevich <fbsdlist at src.cx> wrote:

> All you need is intentionally make one data bit bad.  Put some
> tape on one of the data pads on the DIMM and run memtest ...

and then spend the next couple of hours cleaning the gunk off of
the DIMM and out of the slot :(