Hello, world !!

I'm trying to make an old sun3/50 diskless  boot with a NetBSD 1.0
kernel. I have all the binaries at the right place in the tree  (I
hope), I have several kernels (some from the net, some
made-by-myself), I think I have good config files in etc,
so why is the 3/50 stopping after loading the kernel ??
I've read that on a 3/50, console is on ttya and after loading the
kernel I should have a prompt like "db >" but I get nothing.
I got dbsym binary in xbin.sun3.tar but I don't know how to use it.
Can someone bring me the light, please ?
	Thank you.