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Re: framebuffer mode?



On Sat, Nov 16, 2002 at 05:20:05AM -0500, Mark L. Kahnt wrote:
> 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?

I think Linus sees it as a necessary evil; non-x86 platforms don't all
have actual VGA hardware, so you need someway to get a text console and
fb is it.  I remember someone trying to get a patch to improve it (on
x86) into Linus' tree, and the response was something along the lines of
'either use a text-mode VT or use X and be happy', i.e. it's a dirty
sucky hack that you should avoid if at all possible.

Another interesting point is that the Linux Low-Latency howto says to
never ever switch VTs or scroll them when using fb if you're trying to
record any sort of audio, since the fb code disables all interupts on
your system for some large fraction of a second.

> 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.

You can already do this; give X the 'useframebuffer' option and you can
make use of video cards that X has never heard of.  Of course, as you
say, X supports many more video cards than the kernel does.

-rob

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