There we have it: my CPU is not currently listed. The thing attempts to look up a CPU with vendor ID 0, bus clock BUS166, idhi = 3111 and idlo = 1555. However, it seems that not a single BUS166 CPU is defined. So I wonder how FreeBSD does it?
Looking at the FreeBSD dmesg it appears that FreeBSD has found some way to retrieve the data from ACPI? Because the frequencies go down to 250MHz, and none of the frequency lists does even contain an entry for 250MHz.
Maybe I'll need to debug which entry FreeBSD chooses?