# Support for 3D and dual-head with Radeon HD4850

## JohnLM

Hey! I've been trying to setup dual-screens for this bugger for quite a while with mixed results.

This might be a "catch-all" topic, but I didn't want to flood forum with redundant questions (just yet).

I want to know the current status of support for 3D and dual-head on different drivers/setups, since the up-to-date information is scarce.

I'm going to share my experiences while experimenting with this thing to show what I've tried and perhaps to help others.

My goal is to create "unified screen" (of different resolutions) with 3D acceleration so I can use Blender on two displays.

My system:

Video Board: ATI Radeon HD 4850 PCIe (RV770)

Kernel: gentoo-sources-2.6.39-r3 on amd64 machine

Driver: (fglrx) ati-drivers (various versions, currently 11.8 )

1. Fglrx: Independent desktops

This was my first setup and by far most stable and with least bugs. (EDIT: Open-source driver seems more stable AND works with XRandR)

It ran two separate instances of window manager and they had different DISPLAY vars.

Obviously this also means you cannot move windows between displays, nor you can have windows on separate screens from a single application instance.

This wasn't good enough for me since I want to run Blender on both displays.

Config: aticonfig generated xorg.conf file

2. Fglrx: Xinerama

Supposedly uses fglrx's internal xinerama implementation. It works, but I encountered quite a few bugs including graphical widget corruption (most evident but not limited to firefox), spontaneous pseudo-transparency blacking/corruption (gnome-terminal) and garbled mouse pointer (any monochrome cursor on second display).

While working and I could use Blender on both displays, I wasn't happy with bugs which never disappeared over several ati-drivers versions.

The XVideo extension also wasn't working properly (fixed by using GL output for video).

Config: sligtly altered aticonfig generated xorg.conf file.

The Xlib all the time was complaining about XRandR missing

```
Xlib: extension "RANDR" missing on display ":0.0".
```

Maybe this conflicted with xinerama spawning some of those bugs?

Anyone using this setup?

3. Fglrx: XRandR

Fglrx supposedly supports XRandR 1.2

I rewrote the config xorg.conf removing xinerama and static dual-head configuration, but it doesn't work.

In particular the Virtual setting doesn't have effect (well, not expected effect that is).

The xrandr reports maximum screen of 

```
$ xrandr -q

Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 1440 x 1440
```

in spite of entry in xorg.conf

```
Section "Screen"

   Identifier "The Screen"

   Device     "aticonfig-Device[0]-0"

   Monitor    "Flatron"

   DefaultDepth     24

   SubSection "Display"

      Depth     24

      Virtual   2304 1024

   EndSubSection

EndSection
```

preventing me to add a second monitor.

Yet no error appears to be logged in Xorg.0.log

Has anyone got the XRandR working right with fglrx?

Is there any advantage using XRandR (short of dynamic display configuration, which I don't really need)?

4. Radeon driver: XRandR

So I took a "leap of faith" and tried the open-source driver. Well, honestly I'm surprised, in good sense.

All the bugs I had with fglrx/xinerama setup are gone, and it doesn't appear to be slower by any significant amount.

I didn't however test and compare with glxgears or any 3D game.

There are just a few minor things...

My monitors were reversed (main monitor became "second monitor" and vice versa), which require changing some settings in GUI (panel, icon positions etc.). My framebuffer console is now locked in lower resolution (because of second monitor), but since I don't use it much I can live with that.

I use quite simple xorg.conf config, just to set up large enough virtual screen.

NOTE: To keep both drivers at the same time I compiled an alternative kernel image with the radeon driver compiled in. Running this prevents fglrx from loadins, while running the old one loads it... easy.... no blacklisting necessary.

----------

## eccerr0r

I'm using "option 2" (xinerama).  After upgrading to ati-drivers 11.8, the mouse cursor issue went away for my second monitor that was there for 11.6, and graphics artifacts seems to go down.  It seems to work a bit better after etc-update of the new /etc/ati config files...

Not perfect still, but OK...

Make sure you etc-update the new config files...

My hardware is a RadeonHD 5770, Diamond branded, "two slot width" PCIe.  One DVI LCD, one VGA/Analog LCD, third port unconnected.

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## Spidey

If you are not playing games with it, I strongly recomend trying the opensource drivers. It's wonderful for 2d and simple 3d acceleration, like the one used by desktop environments.

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## JohnLM

 *eccerr0r wrote:*   

> <snip> After upgrading to ati-drivers 11.8, the mouse cursor issue went away for my second monitor that was there for 11.6, and graphics artifacts seems to go down.  It seems to work a bit better after etc-update of the new /etc/ati config files... <snip>

 

Yeah, the cursor bug is gone (I didn't notice until now), but the rest of them persist.

Well, and I did etc-update right away... I always do.

 *Spidey wrote:*   

> If you are not playing games with it, I strongly recomend trying the opensource drivers. It's wonderful for 2d and simple 3d acceleration, like the one used by desktop environments.

 

I use Blender quite a bit and it surely is quite heavy OpenGL program. If the open-source radeon driver can handle it, I might give it a try.

So if I tried this, what would be a fairly straightforward way to keep both of them on my rig? I reckon compiling different kernel is a must, but how do I prevent radeon/fglrx conflict?

Let's say... how do I get one kernel to load only fglrx while other one loads only radeon driver?

btw I was wondering, do either of drivers provide mechanism to accelerate h264, and do ffmpeg/mplayer use it? I deal with "HD" video material a lot.

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## Spidey

I think linux support for gpu decoding of h.264 and vc-1 is not available, only on nvidia. But this info may be outdated.

About Blender, I don't think you will feel the performance decrease.

About kernel modules, I suggest compiling your drivers as modules and BLACK LISTING them when booting with the other kernel. Kernel A black lists radeon drm+kms, kernel B black lists fglrx.

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## DaggyStyle

 *Spidey wrote:*   

> I think linux support for gpu decoding of h.264 and vc-1 is not available, only on nvidia. But this info may be outdated.
> 
> About Blender, I don't think you will feel the performance decrease.
> 
> About kernel modules, I suggest compiling your drivers as modules and BLACK LISTING them when booting with the other kernel. Kernel A black lists radeon drm+kms, kernel B black lists fglrx.

 

afaik, intel has h.264 gpu decoding too

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## Spidey

It seems that the ATI Catalyst, the binary drivers, support XvBA: http://en.wikipedia.org/wiki/X-Video_Bitstream_Acceleration

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## jserink

Hi:

Just just got Xorg xf86-video-ati-6.14.2 working with my new HD6700M based card and the results wree surpurb, unfortunately the external VGA out didn't work. I have lodged a bug with the Xorg team and have moved over to the fglrx driver. My card is not officially supported (there is a wonderful little translucent icon and the bottom right of both my screens telling me so) but the results are ok, at least a single desktop across 2 monitors works. It is buggy though, I came out of lshw -X yesterday and both screens when color inverted...Bizzare! Doing a desktop lock and release fixed the external monitor but not the laptop lcd so I had to exit and reenter X. I am using catalyst 11.8.

AMD's website this morning has released 11.9 but its not yet in portage.

Will need to wait....see if I can find an overlay with it on.

Cheers,

john

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## JohnLM

I gathered courage to switch to the open-source radeon driver.  :Smile: 

And well, I'm impressed... less bugs and less hassle.

XRandR works well. I updated the first post with some details.

I will test it out it, but I'm fairly sure this is the setup I'm staying with.

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## jserink

 *JohnLM wrote:*   

> I gathered courage to switch to the open-source radeon driver. :)
> 
> And well, I'm impressed... less bugs and less hassle.
> 
> XRandR works well. I updated the first post with some details.
> ...

 

My Thoughts Exactly!

I've been forced to use the ati-drviers due to a bug in the xf86-video-ati-6.14.2 with the external VGA out on my new laptop with an HD6700M. The open source driver was superb on the LCD but could not get an external VGA out. Switching to the proprietary driver made the external VGA work but its buggy as Fxxx! If I run lshw the displays go all reverse video, the mouse pointer sometimes changes and all sort of other odities.

The open source driver is MUCH better. A soon as they sort that ext VGA bug, I'm switching back.

Cheers,

john

----------

