maintainer-feedback requested: [Bug 285271] graphics/drm-kmod (20220907_3) host lockup when radeonkms is part of kld_list

Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-x11 (Nobody)
<x11@FreeBSD.org> for maintainer-feedback:
Bug 285271: graphics/drm-kmod (20220907_3) host lockup when radeonkms is part
of kld_list
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=285271



--- Description ---
On a 13.4-p3 host (BIOS-booted), loading radeonkms via kld_list (in rc.conf)
lead to a black screen and complete host lockup (no ping, no response from the
kayboard), the boot never completes and the machine does not reboot by itself.
When radeonkms is explicitly kldloaded in rc.local or by hand by a logged-in
user, console is set to graphics mode and xorg server is started as expected.

The following packages are installed (latest):
$ pkg info | grep drm 
drm-510-kmod-5.10.163.1304000_11 DRM drivers modules
drm-kmod-20220907_3	       Metaport of DRM modules for the linuxkpi-based
KMS components
gpu-firmware-kmod-20241114,1   Firmware modules for the drm-kmod drivers
libdrm-2.4.123,1	       Direct Rendering Manager library and headers

The graghics adapter is a "VGA compatible controller: Advanced Micro Devices,
Inc. [AMD/ATI] RV620/M82 [Mobility Radeon HD 3410/3430]".

As a summary: loading the radeonkms later is okay, loading it earlier isn't.