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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 19 Jan 2022 16:01:01 +0200
Message-ID: <CAHk-=wikFKjwdUBWCLCu=iL3rFq4BDDF0aBGdXC6ay74yJb+5Q@mail.gmail.com>
Subject: Re: [PATCH 2/2] Revert "fbcon: Disable accelerated scrolling"
To:     Helge Deller <deller@gmx.de>
Cc:     Geert Uytterhoeven <geert@linux-m68k.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
        Sven Schnelle <svens@stackframe.org>,
        Javier Martinez Canillas <javierm@redhat.com>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Ilia Mirkin <imirkin@alum.mit.edu>,
        Tomi Valkeinen <tomi.valkeinen@ti.com>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Pavel Machek <pavel@ucw.cz>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Gerd Hoffmann <kraxel@redhat.com>,
        Sam Ravnborg <sam@ravnborg.org>, Claudio Suarez <cssk@net-c.es>
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On Wed, Jan 19, 2022 at 2:29 PM Helge Deller <deller@gmx.de> wrote:
>
> >>
> >> 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").

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).

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

       Linus