GPU hotplug support

[maround95]

Use Case

I have a Lenovo Legion 5 Pro (16ACH6H) laptop with an AMD iGPU and an NVIDIA dGPU. I want the flexibility to use different modules for the dGPU depending on my needs:

1. No module: startup and power-saving.
2. vfio-pci: For passthrough to a vm.
3. nouveau: To use the connectors connected to the dGPU exclusively for driving additional monitors.
4. nvidia (without modesetting): For CUDA workloads, offloaded rendering, etc.

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Workflow involving Hyprland

1. Load nouveau:
   I can now use the outputs connected to my dGPU only.
2. Signal Aquamarine to release the dGPU:

udevadm trigger --type=devices --action=remove --subsystem-match=drm --property-match="MINOR=0"

3. Unload nouveau and load something else.

---

I'm happy to take this to the finish line in case any changes are required.

[ikalco]

looking at some of the stuff changed like closing fds, this might fix/help #83

[maround95]

looking at some of the stuff changed like closing fds, this might fix/help #83

This patch also allows me to dissociate Hyprland from nouveau if I launch Hyprland with nouveau loaded from the start. I tested it with AQ_DRM_DEVICES=/dev/dri/card1(amd):/dev/dri/card0(nvidia) to set amd as the primary drm backend.

[vaxerski]

lgtm, can you please clang-format all the files though?

[maround95]

Done
FYI There's also hyprwm/Hyprland#8980

[vaxerski]

I realize, but we need a release here first.

[maround95]

I forgot about having this hack because connectors were not being destroyed, so I forced them to. What I wanted was conn.disconnect() to destroy the outputs and then the conn refcount works out.

It's a plus that it looks much cleaner now

[vaxerski]

some final style nits. Content lgtm

[vaxerski]

thanks!