FreeBSD 13 on NUC7 vs. NUC8

dkline201

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We have a dedicated software program running under FreeBSD 13.0 that works fine on a NUC7i3DNH. This application is often used in a 'headless' scenario, where an HDMI display (no VGA available on NUCs) is connected only for monitoring or configuration. The display is ONLY TEXT, typically 80 x 24 format. On the NUC7i3DNH, if the monitor is disconnected and reconnected, either momentarily or after a longer time, the HDMI display refreshes OK as expected.

The NUC7i3DNH is EOL, and we need to use a NUC8i3PNH as a replacement. Again, our dedicated software program is working without problems. BUT, if the HDMI display is disconnected, even just momentarily, the display does NOT refresh. The only way to get the display back on the screen is to reboot. I have not been able to find 'anything' in the NUC8 BIOS that affects this problem. I have tried this with several different monitors. Since we do not use graphics, we have not loaded Xorg, as several other forum conversations suggest for display problems.

This screen refresh ONLY AFFECTS FreeBSD. I have tried Windows 10, and a different Arch Linux application on the NUC8, and on both of these, the HDMI display refreshes OK after disconnect and reconnect.

I 'believe' that this has something to do with FreeBSD 'triggering' (for lack of a better term) the EDID communication between the monitor when disconnected and reconnected. I have tried one of the 'HDMI EDID Emulator Passthrough' devices, and the display refreshes OK after reconnect. This seems to confirm the EDID refresh as the problem. But at $25 each per device , (times several 100's), that is not an acceptable solution.

Anyone out there that has a fix for this?

Thanks, Dale Kline
 

mer

Aspiring Daemon

Reaction score: 390
Messages: 623

So text only, are you loading any of the i915 drm bits in rc.conf?
How about loader.conf, anything in there?
On a system with nvidia cards, I put
hw.vga.textmode="1"
in loader.conf to work around virtual console switching issues, perhaps it would help you?
 
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dkline201

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Messages: 28

Finally found the correct BIOS HDMI video setting. Needed to be set to 'persistent display' to retain the HDMI setting if the display was disconnected. (e.g., KVM switch, monitor powered off, or any other disconnect reason) Thanks for your reply though.
 
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dkline201

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Messages: 28

P.S., The NUC7i3DNH HDMI in BIOS did not have this option, but it remembered the display for reconnect. The NUC8i3PNH had HDMI options in BIOS for the display, and 'persistent' was the correct setting to allow reconnect. That was the difference between the two systems.
 
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