I built my desktop system a decent while back. One of the things that I never got working really well was the multi-monitor hardware accelerated video of the three Asus ENGTX465 video cards. That has finally been corrected.
I started digging in an effort to resolve the issue. The first problem, IOMMU was not working correctly. I dug through everything I could and it all lead to the motherboard BIOS being trash. Not one to give in with saying my Asus P6T7 motherboard was trash I started poking at BIOS options. One managed to remove the kernel warning about the IOMMU, the VT option. I disabled the hardware virtualization option from the BIOS and the IOMMU error was gone.
Now for the configuration. That was actually the easy part. The docs tell that the SLI bridge must be in place. To ensure a clean and problem free playground I:
- Removed xdm from the default runlevel
- Moved my xorg.conf file to a backup location
- Then the simple config line of:
nvidia-xconfig --base-mosaic --metamodes="GPU-0.DFP-0: 1920x1080+0+0, GPU-1.DFP-0: 1920x1080+1920+0, GPU-2.DFP-0: 1920x1080+3840+0"
To my joy and happiness startx brought up all three displays. To check things out glxinfo indicated direct rendering and the nvidia-settings indicated “Base Mosaic” was enabled. Now I have fancy graphics goodness in full effect!