Fwd: absent both plymouth, and video= on linu lines, vtty[1-6] framebuffers produce vast raster right and bottom borders on the larger resolution of two displays

From: Bagas Sanjaya <bagasdotme@gmail.com>
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Regressions <regressions@lists.linux.dev>,
	Linux Framebuffer <linux-fbdev@vger.kernel.org>,
	DRI Development List <dri-devel@lists.freedesktop.org>,
	Linux Nouveau/NVIDIA <nouveau@lists.freedesktop.org>,
	Linux Stable <stable@vger.kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>, Helge Deller <deller@gmx.de>,
	Antonino Daplas <adaplas@gmail.com>,
	Ben Skeggs <bskeggs@redhat.com>,
	Karol Herbst <kherbst@redhat.com>, Lyude Paul <lyude@redhat.com>,
	Felix Miata <mrmazda@earthlink.net>
Subject: Fwd: absent both plymouth, and video= on linu lines, vtty[1-6] framebuffers produce vast raster right and bottom borders on the larger resolution of two displays
Date: Thu, 25 May 2023 17:52:02 +0700	[thread overview]
Message-ID: <e8f93560-a2f6-8e9f-031a-88d333482a31@gmail.com> (raw)

Hi,

I notice a regression report on Bugzilla [1]. Quoting from it:

> Original Summary:
> absent both plymouth, and video= on linu lines, vtty[1-6] framebuffers produce vast raster right and bottom borders on the larger resolution of two displays
> 
> To reproduce:
> 1-connect two unequal native resolution displays to a Tesla or Firmi GPU
> 2-don't have plymouth in use (I don't ever have it installed, so don't know whether it impacts)
> 3-don't include e.g. video=1440x900@60 directive on Grub's linu lines
> 4-boot Tumbleweed or Fedora 38
> 5-switch to a vtty, e.g. Ctrl-Alt-F3
> 
> Actual behavior:
> 1-Both displays utilize the resolution (same pixel grid) of the lower resolution display
> 2-Lower resolution display behaves as expected (light text on black background)
> 3-Higher resolution display uses same pixels as lower resolution display, with light text on black background, leaving right side and bottom raster instead of black
> 
> Expected behavior:
> 1-Both displays utilize the resolution (same pixel grid) of the lower resolution display
> 2-Lower resolution display behaves as expected
> 3-Entire higher resolution display's background is black instead of portions in raster
> 
> Workaround: add e.g. video=1440x900@60 to Grub's linu lines, which causes both displays to use the same nominal mode on the full display space.
> 
> Typical other linu line options:
> noresume consoleblank=0 net.ifnames=0 ipv6.disable=1 preempt=full mitigations=none
> 
> My Tesla has HDMI and DVI outputs, tested with 1920x1200 and 1680x1050 displays.
> My Fermi has dual DisplayPort, tested with 2560x1440 and 1680x1050 displays.
> Occurs Tumbleweed with 6.3.2 and 6.2.12 kernel-default, and with 6.2.15 on Fedora 38, and (partially with Tesla, right side only) with 6.2.12 and 6.3.3 on Mageia 9.
> Does not occur with 6.1.12 kernel-default on NVidia, or with AMD Caicos (Terascale2) GPU, or with Intel Eaglelake GPU.
> Tested only on legacy booting (no UEFI support).
> Others might describe what I call "raster" as multicolored snow.

See bugzilla for the full thread and attached dmesg.

Anyway, I'm adding it to regzbot:

#regzbot introduced: v6.1.12..v6.2.12
#regzbot title: vast raster right and bottom borders on larger display (two displays with inequal resolution) unless forcing resolution with video= parameter

Thanks.

-- 
An old man doll... just what I always wanted! - Clara