Messages in this thread | | | Date | Thu, 6 Aug 1998 16:39:26 +0200 (CEST) | From | Geert Uytterhoeven <> | Subject | Re: 2.1.113 Mill I 8MB & scrollback :-( |
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On Thu, 6 Aug 1998, Jeff Noxon wrote: > On Wed, Aug 05, 1998 at 11:29:16PM +0200, Geert Uytterhoeven wrote: > > That's normal. Scrollback doesn't work on frame buffer devices unless you have > > a virtual screen that's larger than your visible screen. > > > > Vesafb doesn't support a virtual screen. Some other frame buffer devices for > > non-Intel architectures do. > > Let me ask a dumb question: > > Why does scrollback rely on video memory? It's horribly limiting.
Yes it is. But that's the easy way, for both vgacon and fbcon:
- vgacon implements scrolling (and scrollback) by panning the VGA text screen - fbcon implements scrolling (and scrollback) by panning the graphical screen image
In both drivers, scrolling is accelerated by using panning (if possible), and you get the scrollback buffer for free.
> I'd love to have (or be able to configure) scrollback to come from kernel > memory instead. That way I could choose to have a 1MB scrollback buffer > if I wanted... And it would be 1MB of actual *text*, even in the case of > a graphical console.
That would be valuable unswappable kernel memory. Unused video memory is available for free.
And your next question will be: why not implement scrollback for all VCs, not only for the current VC? Because it will consume even more valuable unswappable kernel memory.
Greetings,
Geert
-- Geert Uytterhoeven Geert.Uytterhoeven@cs.kuleuven.ac.be Wavelets, Linux/{m68k~Amiga,PPC~CHRP} http://www.cs.kuleuven.ac.be/~geert/ Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium
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