Re: [linux-dell-laptops] framebuffer and console mode
- On Fri, 2002-04-19 at 19:36, Rajarshi Guha wrote:
> What exactly is the framebuffer? And what s the relation between console modeIBM PC clones have almost always had special video cards that could
> and a frambuffer? Are you actually talking about the X server?
easily do text output. In many ways, it's a rudimentary form of video
acceleration, since you don't need to handle the display pixel-by-pixel
-- the video adapter does that automatically. Of course, text modes are
usually fairly low-resolution anyway. I think the standard on PCs today
is 640x400 (not 640x480, like you might expect), and it's very difficult
to access those pixels directly.
Most other kinds of computers (Macs, Unix workstations, etc.) have
generally not had these kinds of video adapters, and needed to have
another way of drawing text to the screen when people started running
Linux on them. It's a way to emulate what VGA cards do in hardware, so
it can be slow. However, there are advantages. Having a console that
is actually a regular array of pixels means that you can do graphics
easily, without X running. Also, having the kernel handle graphics at a
low level means that X no longer has to run set-UID root and go around
the back of the kernel to access the graphics adapter (something that
could potentially cause the video hardware to do nasty things..)
Hope that helps..
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[ Mike Hicks | http://umn.edu/~hick0088/ | mailto:hick0088@... ]