DisplayLink dock: only one external monitor works, not two #50

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opened 2026-07-14 23:22:27 +00:00 by bram.buijs · 0 comments

bram.buijs commented

2026-07-14 23:22:27 +00:00

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Add an opt-in hardware block (dawo.displaylink.enable, off by default) that appends the displaylink driver to videoDrivers (the nixpkgs module then wires the evdi kernel module and the xorg.conf.d snippet; modesetting stays primary for the internal panel). Only hosts with a DisplayLink dock enable it.

Caveat: the DisplayLink driver is unfree and non-redistributable (nixpkgs uses requireFile). The blob (displaylink-620.zip) must be fetched once from displaylink.com and added to the store; it cannot come from cache.nixos.org. For fleet delivery, build the closure once on a box that has the blob and serve it from the local harmonia cache so devices substitute the built output.

Target: 0.1.2

Tested, written and integrated by a human; the code is AI-assisted.

Reported from the pilot: on a DisplayLink dock only one external monitor works, not two. The core ships videoDrivers = [ modesetting fbdev ], with no DisplayLink driver, so the dock's extra outputs are dead. Add an opt-in hardware block (dawo.displaylink.enable, off by default) that appends the displaylink driver to videoDrivers (the nixpkgs module then wires the evdi kernel module and the xorg.conf.d snippet; modesetting stays primary for the internal panel). Only hosts with a DisplayLink dock enable it. Caveat: the DisplayLink driver is unfree and non-redistributable (nixpkgs uses requireFile). The blob (displaylink-620.zip) must be fetched once from displaylink.com and added to the store; it cannot come from cache.nixos.org. For fleet delivery, build the closure once on a box that has the blob and serve it from the local harmonia cache so devices substitute the built output. Target: 0.1.2 Tested, written and integrated by a human; the code is AI-assisted.

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2026-07-14 23:22:27 +00:00