Novell RPL Boot under VirtualBox

One of my recent retrocomputing projects was to set up a Novell NetWare 4.11 server and boot clients from it. Remote boot, or Remote Initial Program Load, was a common method for booting network clients over the LAN before IP became commonplace.

RPL requires a boot ROM on the network card which finds a nearby server, connects to it and downloads a disk image which it then executes. By today’s standards, it’s trivial – but by late 1990s standards, it was anything but.

Skipping past the reminiscing, I spent a few hours trying to get VirtualBox to do RPL boot. Etherboot doesn’t appear to support RPL, so I tracked down a ROM image on Intel’s website. Intel deprecated RPL around 2005, but they’ve kept an old version of their drivers available which contains a boot ROM image supporting RPL.

After uncompressing the download with 7z (using 7z x PRORPL.exe), I was left with two interesting looking files with the extension FLB. One of these is 63,488 bytes, and the other is 139,264 bytes. Installing these in a VirtualBox machine is straightforward but unfortunately undocumented:

vboxmanage setextradata "vmName" VBoxInternal/Devices/pcbios/0/Config/LanBootRom romLocation

Configuring the virtual machine to use the smaller of the two image was fruitless – VirtualBox didn’t complain at all, but instead ran ‘default’ iPXE code. Only when looking in the Log Viewer did I see a reference to the ROM filename and a strange error such as rc=VERR_TOO_MUCH_DATA.

Trial and error showed that the ROM size must be a few kilobytes below the 64kb limit, and a couple more hours searching uncovered AMD’s website which has a file named "Generic BootRom Utility" which contains a 16kb file, RBOOT.ROM, which is a working RPL boot ROM for AMD PCnet network cards, including the PCnet-FAST III card in my virtual machine.

Re-running the vboxmanage command above with the path to the newly discovered boot ROM works a treat. I can now boot a virtual machine straight off a virtual NetWare server – the details of how to do that are coming in a future blog post.