On 1/19/22 15:01, Linus Torvalds wrote:

On Wed, Jan 19, 2022 at 2:29 PM Helge Deller [off-list ref] wrote:

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Ah, no, that was just the soft scrollback code I was thinking of, which

Right.
That was commit 973c096f6a85 and it was about vgacon, not fbcon.

No, fbcon had some bug too, although I've paged out the details. See
commit 50145474f6ef ("fbcon: remove soft scrollback code").

Yes, but those bugs didn't affected

If I remember correctly (and it's entirely possible that I don't), the
whole "softback_lines" logic had serious problems with resizing the
console (or maybe changing the font size).

Right.
I'm not asking to revert any soft scrollback functions.

It's about if you allow to use the fbdev-drivers hardware acceleration
to move parts of the screen or if you are stuck to software memcpy() and
repainting instead.
None of the bug reports touched that part.

There may have been some other bad interaction with
foreground/background consoles too, I forget.

I think that is independend if you use hardware acceleration or not.

Helge