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Re: Address of second TMSCP controller



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.

-- R


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