Hi - what is the deal with the DMA problem in the AmigaOne hardware? Will this also be an issue for the microA1? If so, what are the implications? Is this a problem for AmigaOS4 as well as Linux?

I've tried searching around on the net for info on this, but havent really found a coherent explanation. Any help on this matter here would be greatly appreciated, as it is a factor in me deciding whether or not to buy an AmigaOne/microA1.

Thanks

@captainmoomoo

My understanding of the DMA issue is that it isn't a 'bug' as such, just the Mai North Bridge chip in the A1 being a bit strange.

Most systems these days implement hardware cache coherency, so that after a device has used DMA to push some data into memory the North Bridge signals the CPU to update its caches to reflect the new data. Linux is written to expect this kind of architecture. The A1 does not have this ability so the OS or driver has to take care of ensuring the cache contents are accurate after DMA operations - software cache coherency, in other words.

This makes running Linux on the A1 a bit of a nightmare but in theory should have zero effect on AmigaOS4, where the OS and drivers are specifically created with the A1 architecture in mind. In practice it's hard to tell just what the situation is as the drivers supplied with the OS4 pre-release are still very much a 'work in progress' and some seem to be about as solid as a haystack in a hurricane.

The best policy is to wait a while and see how things work out. The hardware is probably fine, but there's no sense in betting money on it if you can hold off until the facts of the matter are clearer.

_________________
Who do you serve, and who do you trust? - Galen

@DrBombcrater

[Edited By Alkemyst resaon flame bait] such statements need to be backed up with factual links.



realize

@realize

Quote:

it IS an Articia bug i'm afraid to inform you AGAIN.

Surely it's only bug if the Articia design specification determined that Articia should provide hardware coherency and the implementation of that design failed to meet the specification.

Do you such knowledge of the Articia design?

That's not meant to provoke. I'm just curious why some people are so determined that this is a bug and not (for whatever reason) part of the intended design (which, by all means, you can criticize if you wish).

Cheers,
Rich

@captainmoomoo
Quote:

Is this a problem for AmigaOS4 as well as Linux?

It is a problem only for Linux or any other OS not specially designed for the AmigaOne motherboard.

I personally wouldn't recommend the AmigaOne motherboard of today for anything but running OS4. I was running Debian on it for quite some time and it wasn't really that useful without DMA enabled IMHO. Just run OS4 on it as intended and you won't be disappointed.

I expect the next cycle of OS4 hardware will be more multi-OS friendly if that concerns you.

_________________
ExecSG Team Lead

@realize

Please be careful about making actionable assertions like this on the website please.

Cheers

Dave.

@captainmoomoo

The "bug" (as the Pegasos team prefer to call it) is only a bug if you don't "grok" the Articia chipset and write your software accordingly. This has not been done for the Linux kernel and it is not a high priority at present, so Linux suffers from DMA errors on an AmigaOne.

The OS4 device drivers have been written specifically with the Articia chipset in mind, using the proper documentation and support from Mai, and do not have a problem with DMA.

tony

_________________
cheers
tony

Hyperion Support Forum: http://forum.hyperion-entertainment.biz/index.php

@DaveP+Alkemyst

Ok guys. Here's the challenge then:

1. Who is currently working on Linux kernels for Amiga1??

2. What is the current status of production of the A1 micro?

3. Who has full DMA working in any form on any OS on this platform?

4. How can the platform survive with Amiga OS and not strong Linux support?


No Linux = No Market...

@realize

1) No one (just a guess)
2) Mini A1? Not in production beside developer boards. (just a guess)
( there is no reason mass produce it untill AOS4.0 is ready )
3) beta testers
( as an example see http://www.ann.lu/comments2.cgi?show=1088949734&category=forum&number=183#comment see also comment 193 )
4) You are talking about the Teron HW platform?
By selling the board to professional embedded PPC evaluation needs, etc.

But AmigaOS platform is not anymore tied to any single HW platform.


AmigaOne has 0% possibilieties on Linux Market.
Teron boards have 1% possibilities on Linux Market.
That market was lost yesteryear. LET'S FORGET LINUX ON A1.

"No Linux = No Market..."

That is a too narrow view.
There exists multibilliondollar markets outside the Linux market.
Things like Amiga niche, broadband media niche, multimedia kiosk niche, handheld game console/PDA niche, car automation niche, digital television niche, computer nostalgy niche, rich OS swappers niche, industry automation niche, ...

But surely. It's stupid to spit on the linux Market. I HOPE MAI learns something from this. And I hope that some future third party HW manufacturer has signifficant market beyond Amigans, so that the HW price gets down a little bit. (I think KMOS is looking for that kind of solution amongs others.)

_________________
- KimmoK
// For freedom, for honor, for AMIGA
//
// Thing that I should find more time for: CC64 - 64bit Community Computer?

@captainmoomoo

Yes this will be an issue on microA1 too. Though future amiga boards may not rely on articia S. mai has better arcicias and marvell has it's discovery II chipset (used in peg II)... If nobody (or few) is working on A1 linux kernels don't ever expect usable and current A1 kernel. That however can change.