kern/56575: 9.99.93 i915drmkms regression: BIOS invisible after reboot

[is%netbsd.org@localhost]

>Number:         56575
>Category:       kern
>Synopsis:       9.99.92/93 i915drmkms regression: BIOS invisible after reboot
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Dec 24 20:05:00 +0000 2021
>Originator:     Ignatios Souvatzis
>Release:        NetBSD 9.99.93
>Organization:
	
>Environment:
System: NetBSD henrietta 9.99.93 NetBSD 9.99.93 (GENERIC) #13: Fri Dec 24 15:33:28 CET 2021 ignatios%random84.cs.uni-bonn.de@localhost:/var/itch/sources/cur/oamd64/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:
	When rebooting (shutdown -r) from a 9.99.92/93 environment
	via ddb, or from a 9.99.93+riastradh@'s patch fro 56571, 
	the BIOS text console isn't visible - it stays black (while the
	backlight seems to be on, visible by slightly spilled light at
	the border).

	This is only some sort of configuration problem, apparently 
	BIOS is running fine, booting the default netbsd from the netbsd
	boot selector.

	when "wsdisplay0 at intelfb0 kbdmux 1: console (default,
	vt100 emulon), using wskbd0" initializes, wsdisplay output
	is visible showing the kernel messages from booting and further
	console output.

	BIOS output is normal again when rebooting from a 9.1_STABLE
	kernel.

>How-To-Repeat:
	shutdown -r now
>Fix:

>Unformatted:
 	+ patch by riastradh@ for kern/56571
 	Userland: 9.1_STABLE