Currently only dropbear is patched to allow empty root logins. The same should be done with openssh. Setting: PermitRootLogin yes PermitEmptyPasswords yes allows user 'root' to login without any password.
http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=24288740d0bf0c4e381ee942857a88c23647eafc
verified: git info:c9de24d3f4845251b01e2eab0aeeb7472badc5bb git branch: poky/danny qemu sato-sdk images can be accessed by ssh without passwd as root user, also found below in the file "/etc/ssh/sshd_config" of sato-sdk images: PermitRootLogin yes