Add new module to system

add this in lighttpd/Makefile
$(eval $(call BuildPlugin,authn_potd,Password-of-the-day authentication,,20))
after make, will cause adding following line to .config file
# CONFIG_PACKAGE_lighttpd-mod-authn_potd is not set
how does this happen?
and what do $(eval $(call ....... ) parameters mean?
thank you

Not familiar with lighthttpd package, but I'd venture a guess that that setting is configured thru make menuconfig.

yes. make menuconfig, will see the module.