Subject: Re: New virtual bus.
To: Anders Magnusson <firstname.lastname@example.org>
From: Lord Isildur <email@example.com>
Date: 07/13/1999 15:59:20
> Because mainbus should only be used as a "top-level bus holder" for
> the different machine types. Therefore it is already splitted like:
> sbi* at mainbus0 # 780, 8600
> cmi* at mainbus0 # 750
> bi* at mainbus0 # 8200
> vsbus0 at mainbus0 # 2000, 3100, 4000/x0
> mvbus0 at mainbus0 # MV2, MV3, 3[3-9]00, 4000/x00
but the SBI adapter is a nexus device, just like shac and sgec are,
for example! certainly sgec and shac are of far more limited scope of
operation than an SBI adapter is, but it _is_ connected as a nexus!
> The here given bus is actually the main bus in the specific architecture.
> "Nexus" in the old config system were used as the "master bus" but the
> same for all architectures, which made the structure a little bit
> chaotic in the code.
im meaning nexus in the VAX sense, i.e. a device sharing in that innermost
of buses, to which a processor connects, bus adapters connect, and in later
machines, things like SGEC connect. Those are all nexi, and act with the
same powers as a VAX processor in the nexus. mainbus refers to the nexus
interconnect, and things like processors hang off of the nexus interconnect
and act as nexi. A VAX processor is a nexus device, as are SBIadaptors and
SGEC and so on.
i dont see why we should create another layer to put between nexi and
anything. a SHAC is at the same level and the same privilege as the bus