Re: Address of second TMSCP controller

[Johnny Billquist <bqt%update.uu.se@localhost>]

On 2021-01-30 16:13, Anders Magnusson wrote:
> Den 2021-01-29 kl. 16:50, skrev David Brownlee:
> > On Fri, 29 Jan 2021 at 14:17, Mark Pizzolato - Info Comm
> > <Mark%infocomm.com@localhost> wrote:
> > > [... floating address assignment discussion ...]
> > >
> > > VMS essentially requires that this algorithm is used to assign device 
> > > addresses.
> > >
> > > The complete details of this process are implemented in the simh VAX 
> > > and PDP11
> > > Simulators in the routine auto_config in module PDP11/pdp11_io_lib.c.
> > > A distinctly lesser cut at this is implemented in the simtools 
> > > repository config11/config11.c
> > > module.
> > >
> > > Given the decades of legacy behavior where device addresses are 
> > > explicitly declared
> > > in BSD configurations, it would seem quite late in the day to think 
> > > about changing
> > > how things have always worked for BSD.
> > Things are always changing, and busses behave differently - even
> > nominally the same bus (I2C) can have to have device probe and
> > attachment handled differently depending on differences in hardware
> > implementation.
> >
> > I think it would be reasonable for the uba bus in NetBSD to have an
> > option to follow floating address assignment rules when probing for
> > devices - it could probe for any defined devices without explicit csr
> > addresses using the floating algorithm, and then try to attach any
> > devices with csrs as a second pass.
> >
> > Of course, this is all assuming someone wanted to write the code :-p
> IIRC we had a discussion about this quite some time ago.  It should be 
> rather straightforward to do it.
> Don't remember where it ended up though.

I also remember we had the discussion, and I can't really remember the 
conclusion either.

However, just thinking about it right now, I sortof do not think it's 
that useful.

For that, you should then essentially have a config that lists every 
device with wildcarding. And whenever people change any hardware 
configuration, all CSRs will have to be checked, and possibly a bunch 
changed.

Would that be very useful?

Well, of course, you don't actually need to have every controller listed 
with wildcarding in the config. You'd need to consider this autoprobing 
then, and trying to match up against what is configured. Still have the 
whole issue of any hardware change requiring CSR check and update.

Don't we also have something similar with MSCP? Or can we actually say 
ra* on mscpbus? unit * or something similar? Or don't we need to put a 
few more details in?
Alternatively:
ra0 on mscpbus? unit 0
and so on, but then you might end up with quite a few entries in there, 
since we should atleast cover something like 16 units.

  Johnny

--
Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt%softjar.se@localhost             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol