[oe] Fail to start dropbear

[axel lin]

hi list,
I got below messages when start dropbear... ( config is angstrom/mainstone)
how to fix this?

root at mainstone:/$ /etc/init.d/dropbear start
Starting Dropbear SSH server: Will output 1024 bit rsa secret key to
'/etc/dropbear/dropbear_rsa_host_key'
Generating key, this may take a while...
Exited: couldn't open random device

Thanks for your help.
Axel