"configure --help" shows:
...
--enable-rootfs=[glibc-cgl|glibc-core|glibc-small|glibc-std|glibc-std-sato|glibc-tiny|secure-core|secure-platform]
Specify the file system configuration type.
...
/path/to/wrlinux/configure --help|grep rootfs --enable-rootfs=[cgts-base|glibc-cgl|glibc-core|glibc-small|glibc-std|glibc-std-sato|glibc-tiny|merlin|secure-core|secure-platform]