Re: [gentoo-user] Soft scrolling on framebuffer consoles - New version of the patch.

[Alan Mackenzie]

Hello, Peter.

On Tue, Dec 13, 2022 at 03:44:49 +0000, Peter Humphrey wrote:
> On Monday, 12 December 2022 18:23:28 GMT Alan Mackenzie wrote:

> > Here is the latest version of my soft scrolling patch for the gentoo
> > kernel version 5.15.80.  It will surely work on any reasonably recent
> > kernel version, and also on future versions.  The new version doesn't
> > add any new functionality, it just patches the kernel giving rise to
> > fewer messages from the patch utility.

> You've done it again! What a fine effort. It's saved me much wailing and
> gnashing of teeth.

Thanks for that!

> Is there any chance of enabling gpm to work with it? That would save
> yet more generations of tooth enamel.  :)

Yes, that's been annoying me for some time, too - when the screen is
scrolled, and one tries to mark a portion of text with GPM, it gets the
text that was on the screen before the scroll, and corrupts the display
of the text.

I had a look at it last night, and the problem is that the kernel
doesn't currently store the 32-bit unicode characters which have been
scrolled off the screen - just the 8-bit character glyph codes together
with the 8-bit colour information.  So it would triple the amount of
information stored for each character position.  That surely shouldn't
be a problem on today's machines, though - even with
FRAMEBUFFER_CONSOLE_SOFT_SCROLLBACK_SIZE set to 512 kB, that would only
be 1.5 MB per console.

So yes, this should be doable.  It's definitely more than a day's work,
almost certainly less than a month's.  I'll see what I can manage.

> Seriously, though, it's just wonderful as it is, and we all owe you a debt.

Thanks again!

> --
> Regards,
> Peter.

-- 
Alan Mackenzie (Nuremberg, Germany).