[Openchrome-users] VIA Chrome 9

[Jon Nettleton]

On Wed, 2007-06-13 at 23:21 +0200, Pavel Krejcir wrote:
> Hello everybody,
> 
> I've got an MSI board with VIA chipset VT3230, with integrated graphics 
> card K8M890. After some investigation I've found a 2D driver supported 
> by OpenChrome, and realized that neither a 3D binary driver nor a 3D 
> specification has been published by VIA, and it is likely that it never 
> will be. (Not sure what "Vista Certified" really means, I'm afraid that 
> it could be decrypted as "The vendor promises that free software will 
> never be supplied with appropriate information.")
> 
> I apologize for a bit lengthy  description at this point, I want to be 
> sure that they who are interested in will properly understand what I am 
> actually asking for.
> 
> Well, since I would sometimes like to have a 3D acceleration, a simple 
> solution might be to buy another graphics card which I could be sure a 
> driver exists for. On the other hand, this is not a critical problem for 
> me. I will probably never use the 3D acceleration heavily, sometimes try 
> to draw some things in Blender, nothing more. Of course, this is still 
> possible with disabling DRI, but direct rendering would be better. I 
> believe the card is not as bad as stated on some forums, and for this 
> purpose should be fully sufficient.

The 3d engine for the Chrome 9 chipsets is very different than the
existing Mesa drivers.  The engine is a programmable core and so far we
have no info on it.

> 
> So I started to investigate the problem a bit. I decided not to ask 
> anything on any forum prior getting some basic knowledge. After few 
> weeks I know that the direct rendering for this card is disabled in DRM. 
> I can locate the point and switch it on. After recompiling, installing 
> drm.ko and via.ko and reloading the system, the X gets frozen every time 
> I start the screen saver settings, or run glxinfo. The X is frozen so 
> much that even "Ctrl-Alt-Backspace" does not help. That's fine, and I 
> expect it to do this. I have another computer in LAN so I can safely 
> reboot the affected machine via telnet. I am prepared for real debugging.

There is no reason that DRI can't start working.  Our problem was that
we were having getting DMA working on the IGP/AGP bus.  Once we get that
straightened out we will re-enable DRI.

> 
> Eventually I start to approach the proper topic of this message. I am a 
> little bit stacked now. I know that parsing of the buffer does not cause 
> the crash, it is caused by something called next, when the buffer 
> parsing returns OK. I know that the buffer parsing is called somewhere 
> from mesa, but I cannot compile mesa. There is some syntax error in a 
> module probably not used by my computer at all. I should be able to 
> overcome this and compile mesa in the end, but I am not sure whether it 
> is even necessary.

You will definitely need to be able to compile mesa.  The mesa
openchrome driver handles all the unichrome/chrome9 3d functionality.

> 
> There are at least three components - drm, mesa and openchrome - which 
> somehow collaborate and I do not fully understand how. My guess is that 
> I should focus rather on openchrome than on mesa. So what I really need 
> is if somebody can shed any light on drm-openchrome relationship. What 
> library is loaded in order to parse openGL instruction into the driver 
> command buffer? Is it unichrome_dri.so, or should it be a via_dri.so 
> (which does not exist on my machine)?

Openchrome handles all the 2d rendering and acceleration and DMA.  DRM
handles the direct hardware access.  Mesa handles all the 3d
acceleration and rendering.

Unichrome_dri.so is loaded to handle the openGL, but like I stated
above, won't work the chrome9 chipset.

> 
> If you manage to read it through here then you probably guess that I am 
> ready to experiment with my hardware. I want to try anything I can, 
> however foolish it might appear. So I will appreciate any kind of 
> information from anybody who is willing to share it.
> 
We do want to support this functionality, but are waiting on information
from VIA.  The other option is to do a full reverse engineering of the
3d engine, which is quite in-depth.  Hope this helps.

Jon

> Thanks in advance.
> 
> Pavel
> 
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