I deleted wrongly ,the system-RC10 crashed!
i can't know list of base-packetage, so the mistake will often happen.

I downloaded libiconv.xx.ipk from the feed
unpack this .ipk
cd date directory
cp bin/* /usr/bin/
cp lib/* /usr/lib/
the system is recovered.

this Case is multipurpose.:
when system lacks some base-packetage and crash,
we can unpack them-packetage,
then copy something to relational directory.
and recover the system.