MOP server and utilities for Linux

MOP, the Maintenance Operation Protocol, was developed by DEC (Digital Equipment Corporation). It can be used with VAX, DECstation and other systems. This repository contains a partial implementation, mainly intended for use as a first step when booting NetBSD/VAX over the network. This repository is based on mopd from NetBSD 9.1, which already contained a Linux port. It contains fixes and additions to that port.

Quick instructions

Build via make -f Makefile.linux. If you don't know the VAX MAC address, as root run moptrace -a and attempt a netboot via the VAX console. Create /tftpboot/mop and put boot files there, named with the MAC address of the computer being booted. The hex digits must be in lowercase, without colons, and followed by .SYS in uppercase, such as 08002b90649f.SYS. Run mopd -a as root. Files will now be served to VAXen. Boot your VAX using the appropriate device name, such as b xqa0 on a MicroVAX II or b esa0 on a VAXstation 2000.

You can restrict the programs to a specific Ethernet interface by using the interface name instead of -a. With the -d switch, mopd will stay in the foreground and show debug output on standard output. Otherwise see syslog. MOP is only the first step of booting NetBSD/VAX. Further steps will require other server programs, such as what is described in the guide to netbooting NetBSD/VAX on a MicroVAX II.

Notes

802.3 transport issues

I need to disable 802.3 transport using the -4 switch. Otherwise, KA650 and VAXstation 3100 m38 start 802.3 transfers which fail. Both also make ordinary Ethernet transport requests, and those work.

Conversion of files

MOP loads files via packets which copy blocks of data to specific locations in memory, and then tells the system to start execution at a particular location. The clients know nothing about a.out or ELF, so the server needs to know how to load those files into client memory.

This code needs NetBSD header files to read a.out and ELF files. Because Linux header files are different and won't work, previous Linux ports disabled a.out and ELF support. When built that way, mopd only works correctly with files in MOP format, such as boot.mop and boot.mopformat from NetBSD/VAX 1.4.1 and other versions from that time period. ELF and a.out files are sent improperly, leading to various error messages on the VAX, even CTRLERR, as if there is a hardware problem. This port builds ELF and a.out support on Linux using 3 slightly modified header files from NetBSD.

You can use mopcopy to convert ELF and a.out files to MOP format, but you don't need to do it when mopd supports those file formats. Use mopcopy for debugging the conversion or when preparing files for a version of mopd which doesn't support that file format.

Run mopd as root

The way mopd uses the Ethernet device requires root access. Without root access, you get "Operation not permitted" errors, which you won't see if you run mopd as a daemon.

Partial MOP implementations

Both this code and the code running on the other end is a partial and possibly quirky implementation of the MOP protocol. Making things work is not simply a matter of following the specification. You need to send what the other side can deal with.

Booting ULTRIX

This code can now boot ULTRIX 4.00. See the README.md in the ultrix folder for more information.

dreamlayers/netbsd-mopd