FROM: http://lists.debian.org/debian-user-spanish/2003/12/msg00433.html

Accepted options:

invers no comment…

ypan enable display panning using the VESA protected mode
interface. The visible screen is just a window of the
video memory, console scrolling is done by changing the
start of the window.
pro: * scrolling (fullscreen) is fast, because there is
no need to copy around data.
* You’ll get scrollback (the Shift-PgUp thing),
the video memory can be used as scrollback buffer
kontra: * scrolling only parts of the screen causes some
ugly flicker effects (boot logo flickers for
example).

ywrap Same as ypan, but assumes your gfx board can wrap-around
the video memory (i.e. starts reading from top if it
reaches the end of video memory). Faster than ypan.

redraw scroll by redrawing the affected part of the screen, this
is the safe (and slow) default.

vgapal Use the standard vga registers for palette changes.
This is the default.
pmipal Use the protected mode interface for palette changes.

mtrr setup memory type range registers for the vesafb framebuffer.

vram:n remap ‘n’ MiB of video RAM. If 0 or not specified, remap memory
according to video mode. (2.5.66 patch/idea by Antonino Daplas
reversed to give override possibility (allocate more fb memory
than the kernel would) to 2.4 by tmb@iki.fi)