I have Linux Mint 18.1 running on a setup with i3-6100 and Gigabyte HD 5870. I had been using the iGPU for a month before adding the discrete card and everything was fine. Now I've got a better monitor with two inputs and I'm trying to make GPU passthrough work, but it turns out that even after enabling iGPU dual-monitor in UEFI settings, connecting the monitor to iGPU yields a static image of the boot splash; or, if splash is disabled, simply a black screen. I do not get a "no input" message. I can move the mouse outside of the working screen, but it is not shown on the black screen.
I am using the same motherboard port for the integrated graphics (the D-SUB) as before, and connecting the monitor to only that makes no difference, just like connecting it to the integrated DVI instead of the DVI port on discrete card. The Xorg log shows proper initialisation of both drivers, with no warnings (except the standard missing fonts). The issue is present even after disabling all custom Xorg configs.
- System: Linux Mint 18.1 Serena 64-bit
- DE: Cinnamon 3.2.7
- CPU: Intel Core i3-6100
- GPU: Gigabyte HD 5870 (and the HD 530 on CPU)
- MOBO: MSI B150M PRO-VDH
- Monitor: Gateway FPD1976W