I've run into a small issue. I'm running a new build that I was hoping to set up to use Ubuntu 19.10 as my host system with a VM running Win10, passing through a second GPU and splitting the cores on my processor, for the few applications and games I might want to play there that aren't quite supported on the better side.
System is as follows:
Mobo: AsRock X570 Creator
CPU: AMD 3900X
RAM: 32GB, two 16GB modules
GPU1: AMD Radeon RX 580X
GPU2 (want to pass this card): Nvidia RTX 2080 Super
Boot Drive: Seagate Barracuda 510 NVMe M.2 500GB
secondary Drive (Will be passed through): Seagate Barracuda 510 NVMe M.2 500GB
Tertiary Drive (purely storage): Seagate Barracuda Pro Compute 14TB
When i initially set the system up I had used only the RX 580X and the system was able to boot just fine. This was tested in both PCIe 1 and PCIe 4 (the designations for the first two full length PCIe slots on this motherboard) because I had concerns about the RTX2080 possibly being a 3-slot card, meaning it would not fit on the lower slot. Suspicions proved true, I moved the RX 580X to the second slot, did a test boot to make sure everything worked fine, then installed the new card in slot 1.
I hooked up the RX 580X, went to boot, noticed i didn't have a splash screen. This makes sense as the motherboard has no way for me to designate a boot GPU. I assume the output for this is on the 2080 and I'm alright with the 2080 being seen by the Mobo for this as they're all hooked up to the same monitors. I see the plymouth screen, i see login, things seem to be fine. I log in, screen is black.
Realize that the system has moved to using the first GPU for video output.
So here's where the problems start. I tried creating the xorg configuration.
Section "Device"
Identifier "RX 580X"
VendorName "Advanced Micro Devices, Inc."
Driver "modesetting" (Also tried amdgpu and radeon, both of which resulted in the same)
BusID "PCI:34:00"
EndSection
I got the Bus ID from lspci -nn | grep VGA which passed me
33:00.0 VGA compatible controller [0300]: NVIDIA Corporation Device [10de:1e81] (rev a1)
34:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] [1002:67df] (rev e7)
This then started causing loops on login. I would log in, the screen would go black, I'd go back to log in screen. Solution to get back into the desktop was naturally then to delete the xorg.conf file stored in /etc/X11/ and reboot the system.
I also checked Xorg.0.log for errors, to try to figure things out myself. The first part that caught my attention was a parsing error on line 6. Where "EndSection" is. I also figured I could be reading that wrong and that it's counting from 0, stating line 6 would be the empty space after EndSection
the other issue that I ran into was that screen was not being detected.
So I'm unfortunately at a loss. If I can get the system to accept the RX 580X for running the x-server while the 2080 Super is installed I'd be happy, but I'm really unsure where to go from here.
Any help would be appreciated and I'll post any logs or information as needed.
Update 6/9/2020 Thanks to karel for pointing me towards another question that had the instructions on creating a new xorg.conf which fixed the problem. Other issues have shown themselves at this point, but as far as the original question is concerned this is solved.
Update 6/10/2020
For anyone that might experience system hangs after the xorg.conf file is created in the event that both cards are connected to a monitor, the answer is to bind the GPU to VFIO. At least for this case in which the motherboard doesn't give the option to select a primary GPU that differs from the one in the first slot.
