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Re: need a bit of early boot help



Den 2025年11月11日 kl. 11:14, skrev Johnny Billquist:
On 2025年11月11日 06:00, Mouse wrote:
NetBSD 1.6.1 [...] stops in a suspicious place: Right after printing
"root file system type: ffs", on the next line, it prints an 'S' and
hangs.  [simh indicates this] is the first character of this date
stamp:
Sun Nov  9 22:05:50 GMT 2003
[a second mail]
After sending that last email I went back to the console.  It had
been sitting there for maybe ten minutes.  Suddenly it sprang to
life; the date stamp never finished printing (at least not that I
could see, but the console is only running at 1200 baud) but it
printed the 'B' that starts the "Building databases..." line. It
printed a few more lines after that and has now been hung again for
several minutes.  I'm waiting to see if it starts up again.
It printed a few more lines in full, or the first character of each?
If the former, were they printed at full normal 1200 baud, or did each
character take a long time to print?  See below for the relevance.
I can hardly claim any particular insight into the 11/780 in
particular.  But it does occur to me that everything
before-and-including "root file system type: ffs" is printed from
within the kernel, but that timestamp is printed by userland.
That may not be the relevant thing, though.  I don't know 1.6.1 in
enough detail, but perhaps kernel output is polled but userland is
interrupt-driven?  Maybe something is wrong with TXCS-driven
interrupts?
That would be the case, yes. Unless I remember wrong.
Since output from the kernel works, we can at least say that there is nothing wrong with the serial port as such. And the booting process went fine. And VMS also hangs after printing a banner... Which would suggest that there is something funny either with the printing on the console, but which is interrupt related, or something else is getting the machine stuck at an elevated privilege mode, preventing interrupts from being processed. I would actually probably suspect something else isn't completing, and the processor is stuck at some elevated prio. The console is probably working just fine, including when interrupt driven. But something else is not. I assume we're talking about a real machine here. So it has actual Unibus. Simple suggestions would be to remove everything not absolutely required to get the machine running, and really make sure you have bus grants in all Unibus slots not having a card in it. Also, make sure the NPR jumper is in place. This one can be a bit tricky, since it's actually a wire on the back side of the backplane, which might have been cut. There a double height bus grant cards that also covers the NPR signal, but the small square ones do not. And if the Unibus isn't properly configured, you can probably get things hung/stuck for some time.
It's a 780, Unibus is not involved here at all :-)
The PDP11 is connected directly to the backplane (SBI).
-- R


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