I've been reinventing the wheel quite a bit lately and a couple of new
things as well, so I'm glad I was not well-versed in the issues
surrounding this machine in the BSD sphere and elsewhere.
Some new ideas to help those with this machine:
cycle a known-good elsa or permedia with rom disabled through each slot
of an empty card-cage. On each swap, unplug the machine from the wall
and leave the power switch on for a minute or two, then issue an init
at srm. When you run out of slots:
This should pattern the entire bus with a calm elsa stamp.
There are three digital levels to this coherence problem (at least),
and there's the analog one no one seems to have considered as a member
of the whole picture.
I searched for this above and it was no where. I don't think anyone
thought of it.
The system trains. I saw it do this recently with the si3114udc card.
As the card drifts, the system drifts with it, in sympathy. This drift
can become ingrained in the system beyond the digital realm.
I think it is totally worthwhile to consider making a card for this
purpose using a cheap cpld or mcu. There are already pci projects out
there, it could be a snap. I'll look into it, but what it could DO is
repeatedly and visciously assert aligned and properly timed data in the
same way the 3114 and other misbehaved cards assert mis-skewed data and
timing. This, in theory would re-train the entire io subsystem to
compliance with the cards whole and healthy stride, normalizing the
machine for expansion and deployment.
I could really use some feedback. This list has the best there is.
Weaponizing init and prefetch and a crash, exploiting the system is
good, because it can work, but it isn't the whole fix, just a peek at
the mechanisms which can unlock the problem entirely.
So today I added an analog or dumb aspect to what has been seen as a
monolithic problem. It really is a DUAL problem insofar as BSD is
concerned, but for Alpha architecture it is a four-layered problem, as
I see it.
I lack the targam at this depth, so please forgive my terms:
PCI cage physical state (why is this such a stepchild in the process?
And red-headed!)
PCHIP executing saved bitsieve which was generated by init probe before
prefetch is re-asserted (one-boot process).
PCI to EV6 bridge, logic and code the training is here, I believe, and
incredibly active and intrusive. The SRM is a computer inside the
computer.
EV6 bus and its side of the divide.
The way I see it is shooting through three sets of overlapping chain-
link fences. If you are sqare to them and a good shot, you will put
your shot through the same hole of the 'grid' and it will land in the
appropriate target zone. If you are at an angle, you will land your
shot, but it will be dislocated from your planned landing spot. The
system is really tolerant to this!, it trains itself..... If I keep
hitting the fences, the fences move to accommodate my shot, as though
the strikes were physically enough to do that.
I think the dec hardware guys wanted to puke when they were told to
hang pci off ev6 AND as the only available bus. They hated it with
their whole souls. So, the implemented the most rigorous and perfect
implementation of the 'standard' they could. It was so good and so
rigorous the software guys had to eat the puke they'd made the hardware
guys egest. We are dealing with the aftermath of that battle, is my
take. I'm just looking at the machine.
So if it can fail for bad training, why not try GOOD training?
Some of you may remember me. I've been here since 1997 or so?
I have no formal education at all. I have 40 years of computing
experience and have gotten this far in the project through logic and
theory and the output of the framebuffer in various failure modes.
One, for example would just look corrupted to a LOT of people, but it
looks like a loader for a demo on an 80's 8-bit decompressing its
payload. That is informative. I realized that the framebuffer had
overflown into main memory and I was seeing the contents of that in
this familiar way. That is science, even if it is using in-situ
diagnostic tools. Using this as a primary window into the system I've
built the theory as expressed here. A smarter person would use
expensive tools I don't have, and those have been applied already I'm
sure.
I'ts been awhile is all. I've been lurking.
Please holler!
Best,
Technoid Mutant
Jeffrey S. Worley
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