kern/59788: [nouveau] boot-time freeze without a physical monitor

[jkoshy%netbsd.org@localhost]

>Number:         59788
>Category:       kern
>Synopsis:       [nouveau] boot-time freeze without a physical monitor
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 24 13:40:00 +0000 2025
>Originator:     Joseph Koshy
>Release:        NetBSD 10.99.4 (GENERIC) #0: Sat Nov 22 13:14:18 GMT 2025
>Organization:
	The NetBSD Project.
>Environment:
System: NetBSD nbc1 11.99.4 NetBSD 11.99.4 (GENERIC) #0: Sat Nov 22 13:14:18 GMT 2025  jkoshy@nbc1:/home/jkoshy/obj/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
	Recent -CURRENT kernels freeze on boot if a physical monitor is
	not connected to the graphics card on the system.

	The relevant dmesg(1) lines, from a boot with a monitor attached
	are as below:

	Nov 22 16:30:58 nbc1 /netbsd: [   1.0325254] nouveau0 at pci1 dev 0 function 0: NVIDIA GeForce GTX 750 Ti (rev. 0xa2)
	[...]
	Nov 22 16:30:58 nbc1 /netbsd: [   2.9063901] nouveau0: NVIDIA GM107 (117000a2)
	Nov 22 16:30:58 nbc1 /netbsd: [   3.0158186] nouveau0: bios: version 82.07.32.00.26
	Nov 22 16:30:58 nbc1 /netbsd: [   3.0158186] nouveau0: interrupting at msi5 vec 0 (nouveau0)
	Nov 22 16:30:58 nbc1 /netbsd: [   3.0158186] nouveau0: fb: 2048 MiB GDDR5
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: autoconfiguration error: error: bus: MMIO read of 00000000 FAULT at 3e6684 [ IBUS ]
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] Zone  kernel: Available graphics memory: 9007199252881432 KiB
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] Zone   dma32: Available graphics memory: 2097152 KiB
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: VRAM: 2048 MiB
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: GART: 1048576 MiB
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: TMDS table version 2.0
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB version 4.0
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB outp 00: 01000f02 00020030
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB outp 01: 02000f00 00000000
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB outp 02: 08011f82 00020030
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB outp 03: 02022f62 0f420010
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB conn 00: 00001030
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB conn 01: 00010131
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: DCB conn 02: 00002263
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] nouveau0: DRM: MM: using COPY for buffer copies
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
	Nov 22 16:30:58 nbc1 /netbsd: [   3.2258159] [drm] Driver supports precise vblank timestamp query.
	Nov 22 16:30:58 nbc1 /netbsd: [   3.3058158] nouveaufb0 at nouveau0
	Nov 22 16:30:58 nbc1 /netbsd: [   3.3058158] [drm] Initialized nouveau 1.3.1 20120801 for nouveau0 on minor 0
	Nov 22 16:30:58 nbc1 /netbsd: [   3.3058158] nouveaufb0: framebuffer at 0xe0140000, size 1920x1080, depth 32, stride 7680
	Nov 22 16:30:58 nbc1 /netbsd: [   5.3058121] nouveau0: autoconfiguration error: error: DRM: core notifier timeout
	Nov 22 16:30:58 nbc1 /netbsd: [   7.3058074] nouveau0: autoconfiguration error: error: DRM: base-0: timeout
	Nov 22 16:30:58 nbc1 /netbsd: [   7.3958074] wsdisplay0 at nouveaufb0 kbdmux 1: console (default, vt100 emulation), using wskbd0
	Nov 22 16:30:58 nbc1 /netbsd: [   7.4058072] wsmux1: connecting to wsdisplay0
	Nov 22 16:30:58 nbc1 /netbsd: [  21.6659504] wsdisplay0: screen 1 added (default, vt100 emulation)
	Nov 22 16:30:58 nbc1 /netbsd: [  21.6758235] wsdisplay0: screen 2 added (default, vt100 emulation)
	Nov 22 16:30:58 nbc1 /netbsd: [  21.6758235] wsdisplay0: screen 3 added (default, vt100 emulation)
	Nov 22 16:30:58 nbc1 /netbsd: [  21.6758235] wsdisplay0: screen 4 added (default, vt100 emulation)

>How-To-Repeat:
	1. Build and install a recent -CURRENT kernel on a system with an
	   NVIDIA GTX 750 graphics display card.
	2. Disconnect the physical monitor.
	3. Reboot the system.

>Fix:
	Disabling the 'nouveau' driver in /boot.cfg allows the kernel to boot
	without an attached monitor.

	--- /usr/obj/destdir.amd64/boot.cfg      2019-12-05 22:02:29.000000000 +0000
	+++ /boot.cfg   2025-11-22 17:29:44.661802937 +0000
	@@ -4,3 +4,4 @@
	 default=1
	 timeout=5
	 clear=1
	+userconf=disable nouveau*