[Unmoderated] ArticiaS: mystery finaly solved ? | ANN.lu |
Posted on 08-Jul-2004 06:47 GMT by brotheris | 140 comments View flat View list |
Here's the summary of the last posts from hot topic. It may finaly put some dots on I's. Up to now we have heared a lot of small bits from variuos parties and finaly we can put the puzzle together. Read more about it.
I'll play Amon_Re of the past:
It all started when Chris Hogdes started explaining few things (in this thread and @226 comment).
During DMA transfers, the ArticiaS does not flag accessed memory as "dirty", therefore the CPU does not automatically know, that it has to update/flush its caches
Later (@ comment 247, 248 and others) Bernie Meyer explained how such a lack of feature (or call it a bug) affects stability, performance and may cause data corruption even in AmigaOS-like enviroment while using CachePreDMA()/CachePostDMA().
And then we discover quotes from ArticiaS documentation:
"The snoop cycle is used to probe the primary and secondary cache for updated data when the PCI
accesses DRAM. This is done to maintain data coherency between the Floating Buffer, DRAM and both
caches. The Articia S performs the Snoop cycle. When there is a snoop hit on a modified cache line in
either level one or two cache, the contents are written back directly to the Floating Buffer. A PCI Bus
master can subsequently later on fetch the data directly from the Floating Buffer. The Floating Buffer is
flushed back to DRAM during a PCI write cycle. The corresponding line in level one or level two cache is
thus invalidated. Snoops are hidden, meaning the CPU can continue its current data access without
being interrupted while the Articia S simultaneously queries both caches."
You can find similar information using google cache. It seems like some people lied. Is lack of Cache Coherency a bug or a feature (it was advertised that there is Cache Coherency, so it had to work) ? We may now put this case to rest.
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ArticiaS: mystery finaly solved ? : Comment 97 of 140 | ANN.lu |
Posted by Sammy Nordström on 10-Jul-2004 12:46 GMT | In reply to Comment 95 (Johan Rönnblom): >Sammy, what you're saying is essentially that you consider yourself to
>be the sole judge on truth and falsehood. If you agree, something is
>True. If you disagree, it is False. There are, apparently, no other
>ways to determine truth or falsehood.
No. I'm saying that you should stop these pointless arguments and show us facts that will prove your point. If you have facts, both my and your opinion about it would become completely redundant.
>We have a dispute here. I've told you what I would require to accept
>your stance - just produce a working driver.
Exactly. We'll see when the final release of AmigaOS4 is available. Until then, noone of us has proof and noone is going to convince the other one of anything. That makes this whole discussion pointless, don't you agree?
>All I'm asking is that you do the same - tell me under what
>circumstances you would accept my stance. Can it be so hard?
You're asking me to tell me how you should prove me your theory, while I don't think your theory is possible to prove to begin with since I don't think it's true. Can you say 'catch 22'?
>My opinion is of course that I already have ample evidence in support
>for my stance. And I think you'd be hard pressed to come up with a
>condition for a proof of this bug, that hasn't already been satisfied.
>I think this shows when you refuse to give me such a condition.
No, you have facts proving certain circumstances, but not the cause for those circumstances. You are making use of those facts for specualtions that goes way beyond what we know as a matter of fact, that's all. But then, you're free to *prove* me wrong anytime.
>Your comparison with a court is quite alright. In a court, the
>defendant will of course be more than happy to point out the things
>the prosecutor could have used as evidence but has not: There are no
>fingerprints, there's no DNA, you have no witnesses, you have not
>shown that I have a motive, etc etc.
Don't you get it? You don't even have a case to begin with. It's not until you have a case that you might actually be able to take it to court. Then, and only then will the defendant have to respond to the accusations.
>Anyway, of course I don't expect Sammy to come up with a meaningful
>answer. But maybe someone else who thinks the ArticiaS/A1 is not buggy
>could answer me?
Well, we all know your meaning by this slandering of the competitor to your prefered choice of computer platform... |
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