Yes I know that but the LibreWRT page doesn't say which non free components
are required to run it on other routers so one might get the impression that
they simply didn't port it yet to other routers. Also, searching for LibreWRT
and the router wr841n actually provides some source code results such as
these
http://svn.librewrt.org/librewrt/trunk/target/linux/ar71xx/base-files/etc/defconfig/tl-wr841n-v1/
http://svn.librewrt.org/librewrt/creative-craftsman/target/linux/ar71xx/files/arch/mips/ar71xx/mach-tl-wr841n.c
but there is no explanation about this port on LibreWRT's main page.