This FAQ assumes basic familiarity with the kernel. If the kernel is new to you, here's a great introduction . The frame buffer is one of the new features of the 2.2 Linux kernel. Security is an issue because graphics hardware can copy data to and from memory using direct memory access, so allowing users unfettered access is a potential security hole. The kernel frame buffer interface prevents abuse of the hardware, so X windows running on the frame buffer can be run as the user, with fewer potential security problems.
Performance is mainly an issue where the frame buffer can be used instead of X windows.
You can switch into graphics mode after booting using the fbset program, which can change the resolution, timings, color depth, and acceleration status of the frame buffer. Without this your system will crash. This may be required for other fbset commands as well. Start the frame buffer after booting using the modprobe command. Yes, it can not boot with the Matrox frame buffer in graphics mode as mentioned above.