How do I set the primary display for SDDM/X on a multi-display setup?

I have a desktop computer with Intel integrated graphics on the CPU and a Radeon R7 240 graphics card. My primary, center display is on the Radeon. My secondary display, to the left, is on the Intel integrated graphics. The Dell BIOS allows me to set the primary display for the computer. I have the Radeon set as the default. I triple boot Windows 10, Gentoo, and FreeBSD. Windows 10 and Linux both properly detect the BIOS default and use the display I have configured as the default to be the default display. But for some reason, FreeBSD insists on using the integrated graphics as the default -- ignoring what I have configured in the BIOS (actually, it's probably the drm modules' fault -- not FreeBSD, per se, because it does use the BIOS default until the drm modules load).

Once Plasma 5 started, I was able to easily set the desired default display in Display Settings. But this had no effect on SDDM which still starts on my secondary display. It's a minor nuisance, but it is annoying. How do I ensure that SDDM starts on the preferred display? Or is there a way to force FreeBSD to use my preferred display as the default?
 
Back
Top