--with-root-prefix="": The reason for supplying this option is because of the setup of the e2fsprogs Makefile. Some programs are essential for system use when, for example, /usr isn't mounted (like the e2fsck program). These programs and libraries therefore belong in directories like /lib and /sbin. If this option isn't passed to E2fsprogs's configure, it places these programs in /usr which is not what we want. --enable-elf-shlibs: This creates shared libraries that some programs in this package can make use of. make install-libs: This installs the shared libraries that are built.