[Simh] EXT :Re: Issue #731 - simh PDP11 RSX11M-PLUS Unibus 11/94 system with 2 DEUNA ethernet device XUB not working

Mark Pizzolato Mark at infocomm.com
Mon Jul 29 17:45:51 EDT 2019 

On Monday, July 29, 2019 at 2:39 PM, Johnny Billquist wrote:
> Interesting. But why would everything fail just because you set the CSR
> address manually? This is a mystery to me. As far as I can think, it should still
> work just fine.
> 
> What else is simh doing, that happens differently depending on if it
> autoconfigures things or not? I mean, after all, in the real world, you
> *always* had to set the CSR addresses of all controllers manually.
> You could try and follow the rules laid out by DEC for enabling OSes to auto
> detect what hardware you had, but that was basically the main use for it, and if
> you configured the software yourself, then that reason also went out the
> window.
> 
> And finally, the actual address selected by the OP, was the correct one
> according to the DEC configuration rules for the floating address space.
> So unless simh does something wrong, it should end up with the same
> address, based on the same configuration.
> 
> Curious to get some more details on this problem and solution... :-)

When folks "start" to mess with manually setting any Unibus/Qbus device ADDRESS and/or VECTOR, then autoconfigure is disabled from that point on and the user is obliged to set BOTH the ADDRESS and VECTOR for all devices which are subsequently enabled AND for previously enabled devices if their ADDRESS (or VECTOR) would normally have changed when additional devices are enabled.

The OP set the device address but not the vector.

The OP removed the manual setting of the address and relied on autoconfigure and everything works as expected.

- Mark

> On 2019-07-29 22:45, Hittner, David T [US] (MS) wrote:
> > This was a user configuration issue, where the user accidentally turned off
> SIMH auto-configuration by explicitly setting an address/vector on another
> device, which broke the XUB controller. The issue has been closed by the OP.
> >
> > I took a look at the pdp11_xu.c code to see if I could spot any obvious
> initialization errors without serious debugging, since I know that a double XU
> configuration works correctly on a VAX780.
> >
> > I actually _did_ find a coding error in pdp11_xu.c in my quick review, but it
> makes no real difference, since the fields receive the correct value as the code
> is currently written.
> >
> > In the initialization of xub_reg[], there are two cut-n-paste defective lines:
> >
> >    { BRDATA ( SETUP,   &xub.setup,   XU_RDX, 8, sizeof(xua.setup)),
> REG_HRO},
> >    { BRDATA ( STATS,   &xub.stats,   XU_RDX, 8, sizeof(xua.stats)), REG_HRO},
> >
> > Which really should be initializing the 5th field using the sizeof() the XUB
> structures rather the sizeof() the XUA structures:
> >
> >    { BRDATA ( SETUP,   &xub.setup,   XU_RDX, 8, sizeof(xub.setup)),
> REG_HRO},
> >    { BRDATA ( STATS,   &xub.stats,   XU_RDX, 8, sizeof(xub.stats)), REG_HRO},
> >
> > Mark P, could you peer review and make this simple change to pdp11_xu.c
> for me?
> > I see that the corresponding pdp11_xq.c initialization does not have this cut-
> n-paste defect.
> >
> > David
> >
> > -----Original Message-----
> > From: Simh [mailto:simh-bounces at trailing-edge.com] On Behalf Of Johnny
> > Billquist
> > Sent: Saturday, July 27, 2019 6:30 PM
> > To: simh at trailing-edge.com
> > Subject: EXT :Re: [Simh] Issue #731 - simh PDP11 RSX11M-PLUS Unibus
> > 11/94 system with 2 DEUNA ethernet device XUB not working
> >
> > Paul's point is actually fully relevant even if you do not bring up DECnet. In
> RSX, this is a property already done at the CEX level. CEX knows the DECnet
> address, and sets all ethernet controllers to the corresponding MAC address,
> even if you do not run ethernet.
> >
> > The actual MAC address you set in the simh configuration file is pretty much
> irrelevant. It needs to be the MAC address corresponding to the DECnet
> address you assign.
> >
> > All that said, from what I've received from you in other mails certainly
> suggest that there is some kind of problem in simh. The second ethernet
> controller do not even start.
> >
> >     Johnny
> >
> > On 2019-07-27 20:50, Geoff Conway wrote:
> >> Hi Paul,
> >>
> >> The main test environment I am using is with 1 PC with 2 ethernet
> >> NIC’s each connected to a separate IP router – with one being on the
> >> main Internet router with a 192.168.0.x subnet UNA-0 and the other
> >> UNA-1 being on the private router with the 192.168.10.x subnet.  This
> >> hopefully should not be an issue in my case.
> >>
> >> Thanks for the heads up though – and I will still need to check to
> >> see if I can identify what MAC addresses XU, XUB do have – but as I
> >> have confirmed that the NIC’s are on different segments I should be safe.
> >>
> >> I also usually never ran up the DECNet software fully with just
> >> loading the $CEX environment without starting DECNet Then the BQTCP
> >> code connects to each device via ETHACP and initializes the IP
> >> interfaces – so I usually never ran the DECNet Phase IV networking
> >> software side of things as I didn’t have a second DECNet node to
> communicate with.
> >>
> >> When I couldn’t get anywhere with XUB I shutdown the unibus simh
> >> environment and created the separate Qbus system – with the 2 x DEQNA
> >> with just the $CEX subsystem loaded and with XQ, XQB loaded found
> >> that both ethernet interfaces worked ok with the 2 x DEQNA’s.
> >>
> >> It was only after I had created the 2 independent simh configs with
> >> their own unique disk sets that I realized that they should be able
> >> to communicate with each other through winpcap via attaching XU with
> >> eth6 (internet router) and XUB with eth5 (private lan router) with
> >> the qbus simh system attaching XQ with eth6 and XQB with eth5 the 2
> >> systems overlaying the 2 system Network Interfaces under Windows 10
> >> That was done only as check to confirm the DECNet Phase IV networking
> >> comms was fully working – and works with UNA-0, QNA-0, QNA-1 but not
> >> UNA-1. I suspect that with only $CEX loaded in each simh RSX system
> >> that the driver’s hard-coded MAC address applies with the XU and XQ
> >> drivers each having unique MAC addresses (as do XUB and XQB)
> >> preventing the duplicate MAC address problem occurring when on the
> same subnet.
> >>
> >> If I restrict the unibus system to just loading $CEX (to activate the
> >> ethernet interfaces (but not DECNet) and then startup the BQTCP
> >> software with DEBUG enabled at separate times for each ethernet
> >> device I should be able to at least work out what XUB is meant to be
> >> doing versus what it is doing by comparing DEBUG from XU and XUB and
> >> maybe identify the underlying issue.
> >>
> >> As both ethernet interfaces are configured to be initialized at a
> >> TCP/IP level acquiring an IP address lease via DHCP there should be
> >> an initial sequence of almost identical messages for each of the XU,
> >> XUB drivers which may provide a further clue to this puzzling issue.
> >>
> >> Thanks for your help – you’ve given me another aspect of the drivers
> >> that I need to check to see what MAC addresses each interface has in
> >> this simh environment plusconfirm that this is not the cause of XUB
> >> driver not working.
> >>
> >> Regards
> >>
> >> Geoff
> >>
> >> *From:*Paul Koning <paulkoning at comcast.net>
> >> *Sent:* Sunday, 28 July 2019 00:45
> >> *To:* Geoff Conway <gconway at bigpond.net.au>
> >> *Cc:* simh at trailing-edge.com
> >> *Subject:* Re: [Simh] Issue #731 - simh PDP11 RSX11M-PLUS Unibus
> >> 11/94 system with 2 DEUNA ethernet device XUB not working
> >>
> >> I haven't tried 2 UNA at all, and don't know RSX, but one thing to
> >> watch out for: don't put two Ethernet interfaces on the same LAN if
> >> you're running DECnet (Phase IV).  The reason is that they will both
> >> set the same Ethernet address, from the DECnet node address, so you
> >> have a duplicate address condition.  If both are connected to the
> >> same LAN segment this will make for a mess; if they are connected to
> >> different segments of a switched Ethernet then many packets will be
> >> lost as the switches keep changing their mind about where that address is
> located.
> >>
> >> paul
> >>
> >>
> >>
> >>      On Jul 26, 2019, at 11:26 PM, Geoff Conway <gconway at bigpond.net.au
> >>      <mailto:gconway at bigpond.net.au>> wrote:
> >>
> >>      Hi All,
> >>
> >>      I have just raised an Issue in simh #731 where when recent testing
> >>      with a simh PDP11/94 Unibus system with 2 DEUNA interfaces it was
> >>      found that device XUB did not initialize. Device XU worked normally.
> >>      I have not yet been able have XUB start fully – no matter what
> >>      CSR/VEC combination I have tried. I believe the current CSR & VEC
> >>      are correct as they have been assigned – just that there appears
> >>      some internal disconnect within the XU driver where XUB channel just
> >>      does not do anything.
> >>
> >>      In the equivalent simh PDP11/93 Qbus system with 2 DEQNA both XQ,
> >>      XQB worked normally.
> >>
> >>      The details of the actual system configuration is in the Issues log.
> >>      With the absence of any messages from XUB it appears to be dead in
> >>      the water – although when running the simh environment with DEBUG
> >>      enabled in both XU, XUB I found that XUB stayed in
> >>      xu_process_local() while the XU device had a lot of activity – which
> >>      was expected since XU was working normally whereas XUB was not.
> >>
> >>      Unfortunately as I am not familiar with the XU driver code I have
> >>      not been able to determine why the xub interface is not initializing
> >>      correctly.
> >>
> >>      Regards
> >>
> >>      Geoff
> >>
> >>      _______________________________________________
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> >>      Simh at trailing-edge.com <mailto:Simh at trailing-edge.com>
> >>      http://mailman.trailing-edge.com/mailman/listinfo/simh
> >>
> >>
> >> _______________________________________________
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> >>
> >
> 
> --
> Johnny Billquist                  || "I'm on a bus
>                                    ||  on a psychedelic trip
> email: bqt at softjar.se             ||  Reading murder books
> pdp is alive!                     ||  tryin' to stay hip" - B. Idol
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