I won't duplicate what I mentioned on GH, but here's another warning:
I'm not familiar with the details of the arch cross-tools, but see
this bit of the FBInk doc about toolchain shenanigans, so you don't get surprised if stuff blows up in fun and interesting ways at runtime
...
(There's a very good chance distro-provided cross-toolchains will target a much, much, much too recent glibc/kernel combo, which won't do here).