Got a link? Sounds interesting.
https://news.ycombinator.com/item?id=38852616
TLDR: Linux kernel doesn't have a stable binary kernel interface. And they don't want one.
Given this, the definition of "reproducible build" needs, well, a refined definition, if it includes the Linux kernel.
[1] https://www.kernel.org/doc/Documentation/process/stable-api-...