Bug 219046

Summary:	KMS console on Thinkpad contaminated with garbage
Product:	Drivers	Reporter:	Sergey (h4ckee)
Component:	Console/Framebuffers	Assignee:	James Simmons (jsimmons)
Status:	NEW ---
Severity:	normal	CC:	regressions
Priority:	P3
Hardware:	Intel
OS:	Linux
Kernel Version:	6.6.31	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	Dmesg and kernel config

Description Sergey 2024-07-16 06:50:08 UTC

Created attachment 306575 [details]
Dmesg and kernel config

Hi guys.

Please check a bug filed here https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11192
It looks like the bug is framebuffer related.

I have Thinkpad T430, there were no any issues with kernel version 5.10, while switching to version 5.15 my console framebuffer (KMS+VESA) gets polluted with some trash (looking like unicode characters), meanwhile i can see kernel's output above. Same issue persists on kernel 6.6.31. Tried enabling/disabling different options in graphics & framebuffer submenu without any result. It looks like a change was made after 5.10 which broke the console.

> uname -a
>Linux AXE 6.6.31 #1 SMP Sun, 26 May 2024 10:14:06 +0000 x86_64 GNU/Linux
> 
> doas lspci -vnn -d :*:0300
>00:02.0 VGA compatible controller [0300]: Intel Corporation 3rd Gen Core
>processor Graphics Controller [8086:0166] (rev 09) (prog-if 00 [VGA
>controller])
>        Subsystem: Lenovo Device [17aa:21f3]
>        Flags: bus master, fast devsel, latency 0, IRQ 28
>        Memory at f0000000 (64-bit, non-prefetchable) [size=4M]
>        Memory at e0000000 (64-bit, prefetchable) [size=256M]
>        I/O ports at 5000 [size=64]
>        Expansion ROM at 000c0000 [virtual] [disabled] [size=128K]
>        Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
>        Capabilities: [d0] Power Management version 2
>        Capabilities: [a4] PCI Advanced Features
>        Kernel driver in use: i915
>        Kernel modules: i915

Comment 1 Artem S. Tashkinov 2024-07-16 07:47:01 UTC

> moreover it was unlocked with ivyrain (https://github.com/n4ru/1vyrain). I
> use BIOS/MBR boot with GPT partitions. 

Was the bug present prior to these modifications?

Comment 2 Sergey 2024-07-16 14:03:14 UTC

Ivyrain didn't affect the console output. Only changing kernel version did,

Comment 3 Artem S. Tashkinov 2024-07-17 08:25:22 UTC

> Ivyrain didn't affect the console output. Only changing kernel version did,

You make it sound like it's a regression.

Please perform regression testing:

https://docs.kernel.org/admin-guide/bug-bisect.html

Make sure the known good kernel is not too old.

I.e. it make sense to bisect between 6.5 and 6.6, or 6.6 and 6.6.40, but not between 6.3 and 6.6.