xref: /openbmc/linux/Documentation/fb/gxfb.rst (revision e15a5365)
1=============
2What is gxfb?
3=============
4
5.. [This file is cloned from VesaFB/aty128fb]
6
7This is a graphics framebuffer driver for AMD Geode GX2 based processors.
8
9Advantages:
10
11 * No need to use AMD's VSA code (or other VESA emulation layer) in the
12   BIOS.
13 * It provides a nice large console (128 cols + 48 lines with 1024x768)
14   without using tiny, unreadable fonts.
15 * You can run XF68_FBDev on top of /dev/fb0
16 * Most important: boot logo :-)
17
18Disadvantages:
19
20 * graphic mode is slower than text mode...
21
22
23How to use it?
24==============
25
26Switching modes is done using  gxfb.mode_option=<resolution>... boot
27parameter or using `fbset` program.
28
29See Documentation/fb/modedb.rst for more information on modedb
30resolutions.
31
32
33X11
34===
35
36XF68_FBDev should generally work fine, but it is non-accelerated.
37
38
39Configuration
40=============
41
42You can pass kernel command line options to gxfb with gxfb.<option>.
43For example, gxfb.mode_option=800x600@75.
44Accepted options:
45
46================ ==================================================
47mode_option	 specify the video mode.  Of the form
48		 <x>x<y>[-<bpp>][@<refresh>]
49vram		 size of video ram (normally auto-detected)
50vt_switch	 enable vt switching during suspend/resume.  The vt
51		 switch is slow, but harmless.
52================ ==================================================
53
54Andres Salomon <dilinger@debian.org>
55