Original Realtek Openwrt sources: https://sourceforge.net/projects/rtl8197xd-v2-5-pkg/
Now it has fully working USB for rtl8196e! Yes, you can setup extroot, dlna and other useful OpenWRT features right now.
COMPILATION
You need to have installed gcc, binutils, bzip2, flex, python, perl, make, find, grep, diff, unzip, gawk, getopt, subversion, libz-dev and libc headers.
Run "make menuconfig" , change configuration as you want. Save it.
Execute "make" (build image) or "make V=99" (build image with compiling log).
After error ynyynyyyyynnynyyyynnyyyynnyynnnyyyy' failed change: /staging_dir/host/bin/automake and automake-1.11 line ${([^ \t=:+{}]+)}/ to ${([^ \t=:+{}]+)}/
Run "make" or "make V=99" again.
To build a single package: "make package/
INSTALLING