> The kernel loads fine, but at the end of probing devices I get:
> 
> [...]
> Found boot device le0
> panic: cannot mount root


This is a known problem for the generic 1.0 sparc kernel.

You might try the 1.1 beta distribution which is now available for ftp
at: ftp.netbsd.org:~ftp/pub/NetBSD/NetBSD-1.1-ALPHA/sparc

-pk