Re: Address of second TMSCP controller

[Paul Koning <paulkoning%comcast.net@localhost>]

> On Jan 26, 2021, at 10:56 AM, David Brownlee <abs%netbsd.org@localhost> wrote:
> 
> On Tue, 26 Jan 2021 at 15:20, Anders Magnusson <ragge%tethuvudet.se@localhost> wrote:
>> 
>> Den 2021-01-26 kl. 16:05, skrev Paul Koning:
>>> 
>>>> I imagine you could add a second mtc line to your config at whatever
>>>> address you put your Dilog card at.  ISTR that DEC had a bunch of rules
>>>> for such addresses - the phrase "floating CSR space" comes to mind -
>>> Right.  In the DEC rules, this is a "first unit fixed, rest float"
>>> device, just like the MSCP disk controllers.  The float CSR rank is 30.
>>> Does NetBSD do the floating CSR address algorithm?  If not, yes, just
>>> pick some address and tell the OS what it is.
>>> 
>> No, NetBSD do obey the floating CSR spec.
>> This code is actually from 4BSD which didn't either.
> 
> Is it just a matter of adding mtc* lines to the config for the 2nd and
> subsequent floating address - or is there some risk of false positives
> if a different device is at that address?

Yes and no.  If the address assignment is done correctly the identification will be correct.  If a device is located on an address that belongs to another (whether by float or fixed rules) you get the wrong outcome, of course.

	paul