kern/56858: panic booting without connected monitor

[Thomas Klausner <wiz%NetBSD.org@localhost>]

>Number:         56858
>Category:       kern
>Synopsis:       panic booting without connected monitor
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri May 27 06:40:00 +0000 2022
>Originator:     Thomas Klausner
>Release:        NetBSD 9.99.97/20220526
>Organization:

>Environment:
Architecture: x86_64
Machine: amd64
>Description:
When booting without an attached monitor, NetBSD panics (hand-copied):

breakpoint()
vpanic()
panic()
cnopen() at netbsd:cnopen+0xf2
cdev_open() at netbsd:cdev_open+0x1ab
spec_open() at netbsd:spec_open+0x224
VOP_OPEN() at netbsd:VOP_OPEN+0x3c
vn_open() at netbsd:vn_open+0x32e
do_open() at netbsd:do_open+0xc3
do_sys_openat() at netbsd:do_sys_openat+0x74
sys_open() at netbsd:sys_open+0x24
syscall() at netbsd:syscall+0x196

dmesg|grep nouveau from a boot with connected monitor:

nouveau0 at pci12 dev 0 function 0: NVIDIA GeForce GTX 1050 Ti (rev. 0xa1)
nouveau0: info: NVIDIA GP107 (137000a1)
nouveau0: info: bios: version 86.07.59.00.4f
nouveau0: interrupting at msi11 vec 0 (nouveau0)
nouveau0: info: fb: 4096 MiB GDDR5
nouveau0: info: DRM: VRAM: 4096 MiB
nouveau0: info: DRM: GART: 536870912 MiB
nouveau0: info: DRM: BIT table 'A' not found
nouveau0: info: DRM: BIT table 'L' not found
nouveau0: info: DRM: TMDS table version 2.0
nouveau0: info: DRM: DCB version 4.1
nouveau0: info: DRM: DCB outp 00: 01000f42 04620030
nouveau0: info: DRM: DCB outp 01: 02011f62 04620010
nouveau0: info: DRM: DCB outp 02: 02822f76 04600020
nouveau0: info: DRM: DCB outp 03: 02022f72 04620020
nouveau0: info: DRM: DCB conn 00: 00001031
nouveau0: info: DRM: DCB conn 01: 00010161
nouveau0: info: DRM: DCB conn 02: 00020246
nouveau0: info: DRM: MM: using COPY for buffer copies
nouveaufb0 at nouveau0
kern info: [drm] Initialized nouveau 1.3.1 20120801 for nouveau0 on minor 0
nouveaufb0: framebuffer at 0x80400000, size 3840x2160, depth 32, stride 15360
nouveau0: autoconfiguration error: error: DRM: core notifier timeout
nouveau0: autoconfiguration error: error: DRM: base-0: timeout
wsdisplay0 at nouveaufb0 kbdmux 1: console (default, vt100 emulation)

>How-To-Repeat:
Just boot without any monitor plugged into a NetBSD machine with a Geforce 1050TX.
>Fix:
Please.

>Unformatted: