3.12. What is SVGAlib? Frame buffer? Console?
The console is the dark non-graphical screen you look at when your computer first boots up (and you don't have xdm or gdm running). This is opposed to the X environment which has all sorts of GUI things like xterms. It's a common misconception that X means graphics and console means no graphics. There are certainly graphics on the console—we will discuss the two most common ways to achieve this.
SVGAlib is a graphics library that lets you draw graphics on the console. There are many graphical applications and games that use SVGAlib like zgv (a console graphical image viewer), prboom and hhexen . I happen to be a fan of this library and of graphical console games in general; they are extremely fast, fullscreen and compelling. There are three downsides to SVGAlib. First, SVGAlib executables need to be run by root or be setuid root, however, the library releases root status immediately after the executable begins to run. Secondly, SVGAlib is video card dependent–if your video card isn't supported by SVGAlib, you're out of luck. Third, SVGAlib is Linux only. Games written in SVGAlib will only work on Linux.
Frame buffers are consoles implemented by a graphics mode rather than a BIOS text mode. Why simulate text mode in a graphical environment? This allows us to run graphical things in console, like allowing us to choose any font we want the console to display (which is normally set by BIOS). There's a good Framebuffer HOWTO available from LDP. Graphical console games written using the frame buffer suffer from the same deficiencies of the SVGA library: not all hardware is supported and the code will only run on Linux.
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