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The second stage of Ultrix loading is a struct which tells the kernel things it needs for netbooting. Ultrix needs this and can't use other servers like rarpd, bootparamd and bootpd. The only other server needed is NFS. I don't like how I wrote so much code to create a simple struct. There should be a better way. But this works.
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
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.
The server only supports the first stage of MOP booting
With NetBSD/VAX, you only need the first stage. Afterwards it will use RARP and bootparams, or BOOTP, and then NFS. For Ultrix you can successfully send ultrixload using this program, but then it will perform another load via MOP, which isn't supported by this program yet.
Links
- Link to where this code came from, on the GitHub mirror of NetBSD source
- An older version of this port, at github.com/qu1j0t3/mopd
- DEC AA-D602A-TC Maintenance Operation Protocol (MOP) manual
- DEC AA-K178A-TK Maintenance Operation Protocol Functional Specification manual