[Simh] Raspberry Pi 3 with tun/tap causes XQ to fail

[paulhardy2 at btinternet.com]

I did some quick tests on my Raspberry Pi 3 SimH today. This was giving repeatable 53 errors in the startup self-tests.

1) Switching to the KA655_test.bin made no difference.
2) commenting out the nvram attach then prompted for language, and on entering 4 (UK) then ran through the tests without failure.
3) leaving attach in, but renaming away the existing nvram file, did exactly the same - no error.
4) after (3), I exited to SimH with CTRL/E and exited SimH with quit. This created a new nvram file. Restarting SimH gave same 53 error as original.

Mark, I can send you the nvram file if you want?

My Intel/Windows SimH doesn't seem to giving 53 errors at present, although I'm sure I had them intermittently in the past.

Regards,

-- 
Paul Hardy

-----Original Message-----
From: Mark Pizzolato [mailto:Mark at infocomm.com] 
Sent: 13 November 2017 19:18
To: Jeremy Begg <jeremy at vsm.com.au>; simh at trailing-edge.com
Cc: 'Wilm Boerhout' <wboerhout at gmail.com>; paulhardy2 at btinternet.com
Subject: RE: [Simh] Raspberry Pi 3 with tun/tap causes XQ to fail

On Monday, November 13, 2017 at 2:04 AM, Jeremy Begg wrote:
> I am trying to get SIMH up and running on the ethernet interface of a 
> Raspberry Pi 3.  I have followed the intructions in 
> 0readme_ethernet.txt, installing the libpcap-dev, bridge-utils and 
> uml-utilities packages before building SIMH itself.  I just ran 'make 
> vax' and let it go, and the build to completion.
> 
> My problem is that I just can't get networking going.  To cut to the 
> chase, if I run the simulator without first setting up the br0 and 
> tap0 interfaces, and don't attempt to attach the XQ device, it works 
> fine -- albeit without any networking (as expected).
> 
> If I configure SIMH to attach XQ directly to the Pi's eth0 interface 
> (without configuring br0/tap0) it works on the first run but fails 
> selftest
> 53 on the next run.  If I reboot the Pi and start the br0/tap0 
> interfaces and then run the simulator the VAX console fails selftest 53 again.

Hmm...  I've been trying to track down the 53 test failure, which I can't reproduce here.
In general this should not have anything to do with the networking details you've got setup, but there might be some influence.

A little background explanation is warranted here.  Long ago, when the extended memory was added to the MicroVAX 3900 simulator (extending from 64MB to 512MB), I had observed that boot ROM self test interval timer test intermittently failed (1 out of 10 times).  At the time, I attributed the failures to competing load on the host system while the timer test was running.  To avoid potential problem reports from users the interval timer tests were disabled with a patch to the ROM image.  The resulting KA655x.bin image was unmodified until this past January.  At that time, the timer related plumbing in simh was significantly reworked and it seemed like the ROM self tests should now pass without the need to side step them.  I re-enabled the tests and, in my testing I've run many hundreds of tests without failure, meanwhile there have been some reports like yours... :-(

Since you've got a somewhat reproducible test 53 failure, will you please:

1) send me the configuration file you're loading
2) send me the ka655x.bin or ka655.bin file you may be loading in your configuration file
3) explicitly load the attached ka655x.bin file prior to booting the simulator in your configuration file with:
         sim> load -r ka655x_test.bin
         sim> BOOT  (or BOOT CPU)
4) let me know if you still can observe the self test problems you had previously seen.

If the problem is completely solved, then I'll revise the packaged (and internal) ka655x.bin ROM image and these problems should be behind us.  If the problem persists, then I'll have to look for other ways to address it.

Thanks.

- Mark