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Re: framebuffer mode?

On Fri, 2002-11-15 at 22:45, Pigeon wrote:
> On Fri, 15 Nov 2002 17:07:06 +0530, Sandip P Deshmukh
> <deshmukh@escortsmumbai.com> wrote:
> >hello all!
> >
> >my console seems to be switching into framebuffer mode when i boot.
> >
> >following is the resective line from dmesg:
> >
> >Console: switching to colour frame buffer device 80x30
> >fb0: VGA16 VGA frame buffer device
> >
> >what is the advantage of this mode?
> AFAIK it enables you to (simply) change the text screen size and
> refresh rate from the standard 80x25 to whatever you want, and is
> therefore responsible for SVGATextMode freezing in 1999.
> >does it mean any extra overhead?
> Yes. Every character sent to the screen is sent as a bitmap. How
> significant this is depends on the speed of your machine and your
> sense of engineering elegance. It offends mine, so I use SVGATextMode,
> even though that meant some hacking to get it to work with a SiS6326.

Framebuffer is more significant on some non-i386 systems, where there
isn't quite the normal text mode (at least, according to the kernel docs
related to that code.) I use framebuffer on my machine with the Sun
12x22 font, which is significantly easier to read than the standard PC
font (I worked with the details of typography for over a decade through
the early days of desktop publishing.) Framebuffer is also nice for
being able to view graphical material such as PostScript, pdfs and dvi
without needing to use dead trees or run X11 - useful when somehow X11
gets damaged.

That said, unless you *really* need any of these and they are compiled
in, framebuffer is a re-implementation of text mode in the kernel with
slower methods and more overhead, and as such isn't exactly the most
useful. Or is this one of those parts of the kernel that got included
because some potential 2% of all eventual kernel users might be able to
make use of this (similar to the kernel http server) and somebody was
able to lobby Linus Torvalds enough to get it past his good judgement?

A quick question since I always roll my own kernels: Do the Debian
kernels that come with framebuffer include a variety of fonts for use on
them? If so, you can take a swing at the Sun font by adding the
following to your boot parameters for a kernel at boot time (or append=
in /etc/lilo.conf, and rerun lilo):

 video=<framebuffer video device name>:<resolution and

or whatever of the various other fonts you would care to sample.

In theory, it could be very useful with X11 as the X Server for
FrameBuffer would allow X11 on systems where there was framebuffer
support, but not X11 video card modules, except that at present, X11
supports more video cards.
> >how do i turn it off and on?
> Try vga=0 in your boot parameters (I think, I've never turned it on).
> IIRC it's a kernel feature which my kernel is compiled without.
> >thanx in advance
> >
> >sandip p deshmukh
> >------***--------
> >
> >Have the courage to take your own thoughts seriously, for they will shape you.
> >		-- Albert Einstein
ML Kahnt New Markets Consulting
Tel: (613) 531-8684 / (613) 539-0935
Email: kahnt@hosehead.dyndns.org

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