All JavaStation and sparc64 workstations and servers are capable of booting over a network interface. A network boot-strap procedure can be started by entering the appropriate OpenFirmware command. Some JavaStation-1 systems do not have OpenFirmware and should follow the OpenBoot sparc Diskless NetBSD HOW-TO.
Determining your ethernet hardware address
When you power on your machine, it will print out its MAC address. If it claims your ethernet address is ff:ff:ff:ff:ff:ff, then your NVRAM battery is dead. See the Sun NVRAM/Hostid FAQ. Your system will not netboot without a working NVRAM.
Obtaining an IP address via RARP
When instructed to boot "over the net", your workstation will first try to acquire an IP address by using the Reverse ARP (or RARP) protocol. Thus you need to run a RARP server somewhere in the same network broadcast domain as your workstation. The ethernet address of the machine (needed when setting up the RARP server) should be displayed in the banner when it is powered on or reset.
Sometimes the arp entry gets corrupt on the rarpd server. If this happens, you may need to run (on the rarpd server):
# arp -s client.test.net CC:CC:CC:CC:CC:CC temp
Note: if the client doesn't detect a rarpd server, it will patiently wait for one and will not display any error messages (as described in the rarpd pages).
Downloading the boot loader
If the RARP phase is completed successfully, the firmware in the workstation expects to be able to download a program via the TFTP protocol. It will do this by setting up a TFTP connection to the server that answered the earlier RARP request, and asking for a file named based on the machine's IP address.
Naming the boot loader
The netbooting machine will ask via tftp for a file named as follows:
$ bc obase=16 192 C0 168 A8 1 1 10 A quitThus, a machine which has been assigned IP address 192.168.1.10, will make an TFTP request for `C0A8010A'.
For sparc64 systems, this file should be a symbolic link to installation/netboot/ofwboot.net from the NetBSD/sparc64 distribution. For OpenFirmware-based JavaStation systems, this file should be a link to installation/netboot/bootjs.net from the NetBSD/sparc distribution. Of course this bootloader should be located in a place where the TFTP daemon can find it (remember, many TFTP daemons run in a chroot'ed environment).
Open Firmware uses a generalized syntax to specify the boot device for use with the `boot' command. By default, the JavaStations will attempt to boot from the net automatically.
`boot net netbsd-GENERIC_SUN4U.gz -a'
would select the on-board hme interface located on an Ultra 30.