5.15 regression: CONFIG_SYSFB_SIMPLEFB breaks console scrolling

[Thorsten Leemhuis]

On 21.11.21 12:47, Thorsten Leemhuis wrote:
> Hi, this is your Linux kernel regression tracker speaking.

/me again

> 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.

Javier, I'd be interested in your option on this.

Harald, did you have CONFIG_X86_SYSFB enabled in earlier kernel versions
(and did console scrolling work then)? The answer would help me to
decide if this a regression, as those ideally should be fixed as quickly
as possible.

Ciao, Thorsten

> 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
> web-interface, the getting start guide, and/or the references documentation:
> 
> https://linux-regtracking.leemhuis.info/regzbot/
> https://gitlab.com/knurd42/regzbot/-/blob/main/docs/getting_started.md
> https://gitlab.com/knurd42/regzbot/-/blob/main/docs/reference.md
> 
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> to tell #regzbot about it in the report, as that will ensure the
> regression gets on the radar of regzbot and the regression tracker.
> That's in your interest, as they will make sure the report won't fall
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> 
> Hint for developers: you normally don't need to care about regzbot, just
> fix the issue as you normally would. Just remember to include a 'Link:'
> tag to the report in the commit message, as explained in
> Documentation/process/submitting-patches.rst
> That aspect was recently was made more explicit in commit 1f57bd42b77c:
> https://git.kernel.org/linus/1f57bd42b77c

#regzbot title drm: CONFIG_SYSFB_SIMPLEFB breaks console scrolling