port-amd64/58732: i915drmkms black screen on boot

[bjzuber%icloud.com@localhost]

>Number:         58732
>Category:       port-amd64
>Synopsis:       i915drmkms black screen on boot
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Oct 09 03:30:00 +0000 2024
>Originator:     Bryan Zuber
>Release:        10.0
>Organization:
>Environment:
NetBSD chaos 10.0_STABLE NetBSD 10.0_STABLE (GENERIC) #0: Tue Oct  8 11:27:01 UTC 2024  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
Screen goes black during boot on ASUS Chromebox CN62 equipped with Intel i915 graphics and system is unusable.

userconf disable i915drmkms* allows system to boot, but if HDMI cable is unplugged, boot hangs and system does not respond, therefore cannot be used as a headless server.
>How-To-Repeat:

>Fix: