Created attachment 122733 [details]
screenshot with no corruption

On a screenshot there is no corruption visible.

Some artifacts were visible when I first had different resolutions for the monitors and dragged a window, there would be some artifacts left where the window was, but the windows itself looked fine.

I'm confused by what's going on in your setup... can you also include the output of 'xrandr' and your Xorg log? That should clear things up.

Created attachment 122734 [details]
xrandr commands

These are the commands I enter. I run X on an nvidia GPU and then I want to use a monitor that is connected to a radeon GPU.

Created attachment 122735 [details]
xorg log

Created attachment 122736 [details]
dmesg

Somehow I forgot to check dmesg.

I guess the
[   39.172099] nouveau 0000:00:0d.0: bus: MMIO write of 007c0001 FAULT at 00b010
indicate a problem...

(In reply to Christoph Haag from comment #5)
> Created attachment 122736 [details]
> dmesg
> 
> Somehow I forgot to check dmesg.
> 
> I guess the
> [   39.172099] nouveau 0000:00:0d.0: bus: MMIO write of 007c0001 FAULT at
> 00b010
> indicate a problem...

Nope, that's expected. Something weird with the PMPEG unit on the cards. Although usually the errors happen just once at boot... dunno.

And to further clarify, you get the corruption as in the photo no matter what once you enable the second screen? Given what the photo looks like, seems like there's an issue with strides... perhaps the fb stride isn't being propagated properly? All the dispnv04 code is pretty much stuck in antiquity unfortunately =/ And none of the PRIME stuff has been tested with pre-G80 GPUs.

Created attachment 122737 [details]
journal from running reverse prime from radeon

This may be a different problem, but when I try it the other way around by adding /etc/X11/xorg.conf.d/20-radeon.conf with

Section "Device"
    Identifier     "Device0"
    Driver         "radeon"
    BusID          "PCI:2:0:0"
EndSection
Section "Device"
    Identifier     "Device1"
    Driver         "nouveau"
    BusID          "PCI:0:0:d"
EndSection

then X starts on my radeon gpu. Then I can do
xrandr --setprovideroutputsource radeon nouveau
and then
xrandr --output VGA-1-2 --auto --output DVI-0 --right-of VGA-1-2 --mode 1280x1024
then I get pretty gruesome messages in dmesg.

(In reply to Ilia Mirkin from comment #6)

> And to further clarify, you get the corruption as in the photo no matter
> what once you enable the second screen?

Looks like it. Well, I am not *really* going to use that computer, I am just experimenting with PRIME. So if there are no real users, it might not be worth the time to debug this.

Same problem here, try build a multi monitor setup with a 6600 LE (nouveau) and a Radeon 2400 Pro (radeon). Xinemara works fine, but Reverse PRIME does not.

When i try to render nouveau -> radeon i get a segfault.
When i try to render radeon -> nouveau i get glitches, similar to the one Christoph Haag posted.

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