Here are working instructions for netbooting a miniroot (the server is FreeBSD, but it shouldn't be very different with the tux).
192.168.13.3 primordium.internal.nove.bg primordium
4) /etc/inetd.conf (the tftp line usually is commented out on my host, so don't forget the killall -HUP inetd)
shell stream tcp nowait root /usr/libexec/rshd rshd -L
shell stream tcp6 nowait root /usr/libexec/rshd rshd -L
login stream tcp nowait root /usr/libexec/rlogind rlogind
login stream tcp6 nowait root /usr/libexec/rlogind rlogind
tftp dgram udp wait root /usr/libexec/tftpd tftpd /usr/data/IRIX
#bootps dgram udp ...
5) /usr/src/bin/sh/builtins.def (this step is essential as IRIX expects a Korn shell in place of /bin/sh and Bourne's shell builtin echo is not compatible with ksh, while the external /bin/echo command is. Requires rebuilding of sh after the change - make && make install && make clean)
6) ~/.rhosts (that is, /home/chervarium/.rhosts)
With the files set up like this I'd fire bootpd with
/usr/libexec/bootpd -h 192.168.13.1
(-h option 'coz my SGI/Sun workstations live in separate vlan and the only way to tell bootpd to listen on the appropriate interface is to supply -h), then'd reboot the workstation and choose the "Install System Software" from the PROM menu. I'd set the server to 192.168.13.1 and the path to /usr/data/IRIX/6.5.26/cd1 (that's the latest inst.tools CD, gunzipped and untarred from the SupportFolio files). Boots like a charm. The only drawback of this method is that it'd require
(I'd never ever let anything to log in as root from the network, never).