in Planet Linux OpenSource Debian ~ read.

Installing Debian/sarge on a SunFire 280R (with daily bootimage)

REQUIREMENTS:

At first, you need a running tftp server and a rarp daemon to boot the installer on the box.

# apt-get install rarpd atftpd
# nano /etc/ethers

Put IP and MAC into /etc/ethers file:

   00:03:ba:2b:a3:df 10.0.0.2

Run:

# cd /tftpboot
# wget 	http://people.debian.org/~stappers/d-i/images/daily/sparc64/netboot/boot.img

That the correct bootimage for the box can be found by tftpd, you need to make a symbolic link.

# ln -s boot.img 0A000002

Note:
The name is simply a conjunction of hexadecimal representation of IP address
assigned to the destination machine:

10.0.0.2
| | | |
0A | | |
00 | |
00 |
02 ==> 0A000002

You may also make restriction to which interface the rarpd should be bound in /etc/init.d/rarpd.
If so you need to restart the rarpd:

# /etc/init.d/rarpd restart

INSTALLATION:

Connect the serial port A of the SunFire to another serial port on a second box. Start minicom there, configure your serialport , disable the flowcontrol and use 9600 8N1 settings.

Now you can poweron the SunFire and send them a break signal with .
You have entered the OpenPROM prompt with signaling "ok".

Start netboot with:

boot net debconf/priority=low

Now you should get this screen. Immediately after the box got his IP it will start the tftp transfer of the boot image and boot from:

  Boot device: /pci@1f,0/network@c,1  File and args: debconf/priority=low
  Timeout waiting for ARP/RARP packet...
  Timeout waiting for ARP/RARP packet...
  54e200

Now you can make all your install setting ... after severals questions and settings, you can choose, what you wonna install ... stable, testing or unstable.
I used 2.4 as kernel and the box is running very well til now. :)

Enjoy your life with running Debian sarge on SunFire 280R!