yes thats many lines. but not in the core code, that excludes all the drivers(90%),
drivers dont account for that much. They are roughly 55%
http://cityblogger.com/archives/2008/06/16/linux-kernel-stats and all the archs(5-8%)(except x86 and arm).
I'm sure you know that source code doesn't depends on archs, as archs are handled by compilers.
But I'm sure you know that.
the FreeBSD source only did confuse me.
I think your confusion might not arise from BSD.