Hello Jan-Ralph,
given your reasonable current host Linux I expect an incompatibility of Rump with your recent host tool chain. I did not try this myself but the following error seems to hint that.
On Mon, Aug 14, 2017 at 05:16:54PM +0000, Jan-Ralph Sroka wrote:
inode.c: In function 'swap_dinode2': inode.c:378:21: error: iteration 2u invokes undefined behavior [-Werror=aggressive-loop-optimizations] dp2->di_extb[j] = bswap64(dp2->di_extb[j]);
You may install an older (version 4?) Ubuntu GCC, generate appropriate symbolic links for gcc etc. in a distinct directory, add that directory to the front of your PATH environment variable, and rebuild tool_chain_rump.
Regards