Linux/VAX boot protocol

[Maciej W. Rozycki]

Hi Pekka,

> I'm trying to understand the boot process so that I can emulate the
> relevant parts in QEMU.

 OK, please note some of this only relates to network booting; I don't 
know if anyone has tried booting from a storage device that may be more 
relevant for the emulator.  In particular I think being able to run a 
plain vmlinux image as on some other platforms (MIPS in particular) would 
be desirable.

> Thanks for clearing up a lot of the details! I wonder what
> specifications the people who wrote mopchk were looking at. Or maybe
> they reverse engineered the proprietary image format?

 No idea, please mind this code is 20 years old, according to copyright 
notices.  DEC used to provide decent documentation for stuff that mattered 
to users, so I wouldn't be surprised if all of this was properly described 
somewhere.  Or at least there may have been a system header available for 
the data structures used.  I reckon there was a system package with 
software for users to prepare their own bootstrap images.

 Documentation for the MOP protocol itself used to be available.

  Maciej