Sun JavaStation Krups (aka NC) - 2025

from wikipedia andunder CC BY-SA 4.0, Adrian Cockroft

My main notes here are on getting Linux running on it, booting off a modern Linux host, with some notes on how to rebuild kernels.

The Krups is not that different from a SPARCStation (4ish) but has very limitted IO. The only permanent storage is a removable Flash DIMM that is supplied with JavaOS. It's also different enough to need it's own Linux kernel build.

Existing websites

1. The Sun JavaStation NC Howto from 2001
2. Robert H. Thornburrow's site from 2023

The boot process

1. Avoid JavaOS
2. Netboot Linux

Avoid JavaOS

While other docs have mentioned keyboard shortcuts during boot to avoid booting JavaOS, I've not managed to make any of those work; one possibility is that is because I'm not using a real Sun keyboard on it, although the ctrl-alt-esc combination does bring the help menu up (only if the NIC is plugged in).

Like most SPARC systems, it has openprom boot firmware, although that seems more limited than other SPARC systems I remember. Hitting break on the serial near the start of boot gets into it's prompt, and can be used to manually boot from there.

However, having to hit break at just the right point on each boot is a pain, so I took the JavaOS SIMM out. It was in the white socket on the right hand side in the picture below:

The trickiest bit of this is opening the case, which is plastic clipped together - on my Krups the plastic is brittle and a lot of the clips completely popped off, and I cracked one side - so be more careful than me!.

Netbooting Linux

The JavaStation ethernet is connected to a segregated LAN, with a Debian Trixie Linux server acting as DHCP server. On this server, the DHCP server is provided by the modern kea system rather than the older isc package. Care needs to be taken to get the config just right since the Krups firmware can be a bit picky.

Remember to ensure your firewall lets the dhcp and bootp etc through

Setting up bootp/dhcp

First I specified for it to only run on the isolated interface I was using for the JavaStation:

"interfaces": [ "enp4s0" ]

Then, since the JavaStation actually uses the older bootp rather than dhcp, this needs enabling in kea:

    "hooks-libraries": [
      { "library": "/usr/lib/x86_64-linux-gnu/kea/hooks/libdhcp_bootp.so" }
    ],

    "reservations": [
        {
            "hw-address": "08:00:20:95:1f:4e",
            "ip-address": "192.168.69.2",
            "next-server": "192.168.69.1",
            "boot-file-name": "C0A84502"
        }
    ]

I also added an entry for that IP address in my /etc/hosts as 'krups'.

TFTP booting Proll

First install the tftpd (I installed debian's tftpd-hpa package) and figure out where it ones files, in my case it serves from /srv/tftp/.

Next download:
My proll build
and put it in the tftp server directory (i.e. /srv/tftp/). Create a symlink from it to the hex for each javastation you need to boot:

ln -s javastation-krups-proll.19dagb C0A84502

(Note: Older versions of Proll didn't all load the .CMDL file, I enabled it in my build so I could specify some NFS flags)

Create /src/tftp/XXXXXXXX.CMDL (fill in your hex IP) with your favourite editor with the content:

ip=bootp root=/dev/nfs nfsroot=/tftpboot/%s,v3 console=ttyS0 debug

These are parameters to the guest kernel we're about to boot, the '%s' is expanded to a decimal IP address of the guest, and the v3 is specifying the NFS version. Specifying v3, and having a v3 enabled JavaStation kernel is needed since newer Linux hosts don't support v2 any more.

I've built two kernels that are suitable for this configuration, with NFSv3 enabled, details on building them is included below, but here are the images:

My 2.4.27 build

My 2.5.1 build

Download these into the tftp directory and then symlink one to XXXXXXXX.PROL.

If all works well, then when powering on the JavaStation, after a few seconds you should see the Proll boot messages in the bottom right of the monitor:

After a few seconds this should be replaced by a full screen Linux console with Tux (and a sun burst) at the top left. This can't boot fully yet however since we haven't got a root filesystem.

Building a root filesystem

On the host, install qemu-user (which tends to make cross architecture debootstrap more reliable). Then did:

debootstrap --arch=sparc sarge /opt/sarge/home/sparc

/opt/sarge/home/sparc  krups(rw,no_root_squash)

Debootstrap only does a very basic install, so it may need some cleanup - and remembering this is a very old Linux most of this is in the simpler older config files such as /etc/inittab. I commented out all except the tty1 and ttyS0 entries in inittab, just leaving a single console and a serial console.

If this has all worked out right you should be able to see a Linux userspace booting:

Building Proll and the Kernel

Building old code tends to need old tools, and there's some guess work to be done in finding a good combination that works. In addition, building old compilers can also need old tools. Fortunately building old code on new machines is at least fast, even for gcc and a kernel.

A starting point

Building cross tools

apt-get source binutils
apt-get source gcc-3.3

In the binutils-2.15 directory that has been created:

./configure --program-prefix=sparc-linux- --prefix=/home/cross/build --target="sparc-linux"
make
make install

In the gcc-3.3-3.3.5 directory that has been created:

export PATH=/home/cross/build/bin:$PATH
./configure --program-prefix=sparc-linux- --prefix=/home/cross/build --target="sparc-linux"
make
make install -k

Note the make will fail as it tried to start building some userspace libraries we don't need, the -k on the make install tells it to ignore errors and plough on. This got me enough to work with, including sparc-linux-gcc.

elftoaout

rpm2cpio elftoaout-2.3-bp155.2.10.src.rpm
cpio -idv \< ../elftoaout-2.3-bp155.2.10.src.rpm.tar
tar -xvzf elftoaout-2.3.tgz
make

Building Proll

To build it, just ensure the cross tools are in PATH and then, inside the krups directory issue:

make CROSS=sparc-linux-

Building Linux 2.4.27 kernel

apt-get source kernel-source-2.4.27

To build,

make ARCH=sparc CROSS_COMPILE=/home/cross/build/bin/sparc-linux- oldconfig
make ARCH=sparc CROSS_COMPILE=/home/cross/build/bin/sparc-linux- vmlinux

./elftoaout -o vmlinux.aout vmlinux

Building Linux 2.5.1 kernel

This resulted in my hacky patch and config.

This can be build in the same way as 2.4 above.

Failing at Linux 2.6.x

Early 2.6 etc didn't have the level of CI of modern Linux, many versions just didn't build for SPARC for example. So finding a good starting point is tricky.

Troubleshooting

1. tcpdump is your friend when looking at early boot failures before the kernel has loaded.
2. If you've configured your DHCP server to only serve a separate interface, it often requires that the interface is up when the DHCP server is started. Thus if you're just using a cable to the JavaStation you need to turn it on, then start the DHCP server (and then possibly restart the JavaStation if it timed out waiting for the DHCP and displayed a ? in the corner).
3. All my tests have been done with a PS/2 keyboard plugged in, I've seen suggestions the boot flow is different when there isn't one.
4. The boot prom is visible on the serial console, as is the kernel console.
5. With an NFS root, the logging happens over NFS, so once the kernel and userspace is running you can just look at the log in /tftpboot/<ipaddress>/var/log
6. For early kernel debug, qemu-system-sparc can boot the aout kernel directly, with a line like qemu-system-sparc -kernel ./vmlinux.aout -M SS-4 -nographic. This has helped me debug some early failures, but I've got versions that fail on real hardware but work there, possibly since it isn't quite a SparcStation-4.

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