Meltdown is the result of an error made by Intel. Some Intel processors are
susceptable to it. It is not that difficult to work around in the Unix world,
but it is fairly easy to exploit if that has not been done.

Spectre is a more fundamental exploit, and it's likely the first of a whole
new class of timing-related exploits. It's difficult to take advantage of
compared with Meltdown. However, any processor with a sufficiently precise
timer and low-jitter system clock that uses branch prediction is vulnerable.
Which means just about everything post-vax, pretty much. This is a far more
alarming thing, not really even related to Meltdown.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."