What is the oldest x86 processor that is still supported by a modern Linux kernel in present time?

The Covox Speech Thing (CST) was a sound card released in 1986 by Covox, Inc to enable computers with parallel ports to have sound capability. Unlike modern machines, proper sound support was not a given on computers in that era and the Soundblaster by Creative has yet to be released.

(This is a long 5600+ words post, I recommend reading this from a tablet or computer)

(This is a long ~2900 words post, I recommend reading this from a tablet or computer)