Re: Mopd which works with ELF and a.out in Linux and can netboot ULTRIX

[David Brownlee <abs%absd.org@localhost>]

On Sat, 31 Oct 2020 at 15:29, Maciej W. Rozycki <macro%linux-mips.org@localhost> wrote:
>
> On Wed, 28 Oct 2020, David Brownlee wrote:
>
> > > > I've committed the pfInit and 1k/4k changes.
> > > > One quick question on the mid 0 change - should the N_BADMAG (ex) &&
> > > > N_BADMAG (ex_swap)) check be conditionalised on mid 0?
> > >
> > > I don't think the N_BADMAG (ex) check should be conditional, because it
> > > seems all a.out files should have magic numbers there, which are the
> > > same across different operating systems. Anyways, if some foreign a.out
> > > files used different magic numbers, mopd couldn't tell if the file is
> > > OMAGIC or NMAGIC, which could cause problems. So it seems best to reject
> > > such files.
> >
> > Ah, yes, now I actually read the code, that makes more sense :)
>
>  For the record: some 20 years ago I was in a need for a usable `mopd'
> daemon under Linux, so I grabbed whatever sources were available, cleaned
> some stuff up, added proper packet socket level (data link layer level)
> multicast support (no need for allmulti or promiscuous operation), added
> FDDI support, i.e. SNAP frame essentially (so that I could boot my
> DECstations over DEFZA and DEFTA interfaces, which do support it), and
> finally added ELF support so that I didn't have to go through hoops to
> boot ELF images.
>
>  I continue using this stuff to this day (most recently earlier this
> month), although there are a couple shortcomings, most notably if an
> interface `mopd' listens on goes down then the daemon dies and has to be
> restarted (I guess a socket error isn't handled correctly; proper event
> handling would have to be added for interfaces going down and up, so that
> multicast group membership is correctly maintained over the interfaces
> listened on, which is all by default).
>
>  Regrettably I was unable to find any package maintainer or proper
> upstream sources, so my patches were never submitted anywhere, but I
> packaged them into the RPM format (one of the two major Linux package
> formats) in the source and a couple of binary forms and published on my
> FTP site, in addition to loose patches.  This stuff is still online, so if
> anyone is interested, please feel free to have a look at:
>
> <ftp://ftp.linux-mips.org/pub/linux/mips/people/macro/mopd/>
>
>  I'll be happy to have this stuff upstreamed too even now after those 20
> years if there's still something missing from whatever `mopd' sources are
> considered the reference these days.

I think the canonical mopd was (and may still be) in NetBSD
http://cvsweb.netbsd.org/bsdweb.cgi/src/usr.sbin/mopd/ but active
development directly intended to support Linux while not breaking
existing platforms is happening in dreamlayers' repo
https://github.com/dreamlayers/netbsd-mopd (which I hope to sync back
into NetBSD's version on an ongoing basis)

It would be very cool to merge back all of your patches which still apply :)

Thanks

David