Removing build metadata, for reproducible kernel builds

[Alfred Perlstein]

On 12/2/15 9:36 AM, Ed Maste wrote:
> The main issue currently preventing kernel builds from being
> reproducible[1] is the build metadata itself that's included (time,
> user, host, build path). In order to make the kernel build
> reproducible I plan to remove these by default, and add a src.conf
> knob to enable them for developers who want them in their own builds.
>
> The user-facing effect of this is that the kern.version sysctl no
> longer conveys this information, and uname -a changes from something
> like:
>
> FreeBSD ref11-amd64.freebsd.org 11.0-CURRENT FreeBSD 11.0-CURRENT #0
> r288681: Mon Oct  5 01:40:11 UTC 2015
> peter at build-11.freebsd.org:/usr/obj/usr/src/sys/CLUSTER11  amd64
>
> to something like:
>
> FreeBSD feynman 10.2-STABLE FreeBSD 10.2-STABLE #44
> r288174+7644546(stable-10) amd64
>
> The current version of the change is available for review at
> https://reviews.freebsd.org/D4347.
>
> [1] See https://reproducible-builds.org/ for more information on the
> reproducible builds project.

Can it not be done as a kernel module (containing the strings/numbers) 
or injected after the fact by editing the binaries?

This info is very useful.

-Alfred