5.15 regression: CONFIG_SYSFB_SIMPLEFB breaks console scrolling

[Thorsten Leemhuis]

Hi, this is your Linux kernel regression tracker speaking.

On 16.11.21 05:52, Harald Dunkel wrote:
> 
> if I enable CONFIG_SYSFB_SIMPLEFB in 5.15.2 and use grub's default
> configuration
> (Debian sid amd64), then a few lines at the bottom of /dev/tty1 including
> login prompt are off-screen. Scrolling is broken. I can login, though.
> 
> Enabling GRUB_TERMINAL=console in grub doesn't make a difference. Using
> the same kernel except for CONFIG_SYSFB_SIMPLEFB the problem is gone.
> 
> Graphics card is a GeForce GTX 1650. I tried with both CONFIG_DRM_NOUVEAU
> and proprietary graphics drivers disabled.
> 
> Attached you can find the config file. Please mail if I can help to track
> this problem down.

Thx for the report. I'm not totally sure if this is a regression, as
that's a new config option. But it might be one considered a successor
to an older one, hence it might count as regression. Adding two
developers and a mailing list to the CC, hopefully someone can clarify.

TWIMC: To be sure this issue doesn't fall through the cracks unnoticed,
I'm adding it to regzbot, my Linux kernel regression tracking bot:

#regzbot ^introduced 8633ef82f101c040427b57d4df7b706261420b94
#regzbot title CONFIG_SYSFB_SIMPLEFB breaks console scrolling
#regzbot ignore-activity

Ciao, Thorsten, your Linux kernel regression tracker.

P.S.: If you want to know more about regzbot, check out its
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https://linux-regtracking.leemhuis.info/regzbot/
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That aspect was recently was made more explicit in commit 1f57bd42b77c:
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