I'd appreciate comments on this please...
How to use the vesafb device
Version 0.0.1 (Last revised 28 July 1998 by Alex Buell)
Released under the terms of the GNU LGPL version 2.
Alex Buell can be contacted on alex.buell@tahallah.demon.co.uk
Contents
1. What is vesafb?
2. What is a framebuffer device?
3. How do I activate the vesafb drivers?
4. What VESA modes are available to me?
5. Miscellaneous
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1. What is vesafb?
Vesafb is a framebuffer driver for Intel architecture that works with
VESA 2.0 compliant graphic cards. It is closely related to the framebuffer
device drivers in the kernel.
Unfortunately, you can not use vesafb successfully with VESA 1.2 cards.
This is because these 1.2 cards do not use framebuffering. It may be that
someone will write a vesafb12 device driver for these cards, but this will
use up precious kernel memory. :o(
2. What is a framebuffer device?
A framebuffer device is an abstraction for the graphic hardware. It
represents the frame buffer of some video hardware, and allows application
software to access the graphic hardware through a well-defined interface,
so that the software doesn't need to know anything about the low-level
interface stuff [Taken from Geert Uytterhoeven's framebuffer.txt in the
linux kernel sources]
3. How do I activate the vesafb drivers?
[Note: The information is based on what I know and have achieved using the
Linux kernel v2.1.111 on a P75+ with an ATI VideoExpress 2MB graphic card.
Feel free to email me with information/special cases for different graphic
cards]
Assuming you are using menuconfig, you will need to do the following
steps:
Go into the Code Maturity Level menu, and enable the prompt for
development and/or incomplete drivers [note this may change for future
kernels - when this happens, this HOWTO will be revised]
Go into the Console Drivers menu, and enable the following:
VGA Text Console
Video Selection Support
Support for frame buffer devices (experimental)
VGA Chipset support (text only)
VESA VGA Graphic console
Advanced Low Level Drivers
Select Mono, 2bpp, 4bpp, 8bpp, 16bpp, 24bpp and 32bpp packed
pixel drivers
VGA character/attributes support
Ensure that the Mac variable bpp packed pixel support is not enabled. [As
of 2.1.111, this seems to get enabled if Advanced Low Level Drivers is
initally selected]
Make sure these aren't going to be modules. [Not sure if it's possible to
build them as modules yet - please correct me on this]
Then rebuild the kernel, modify /etc/lilo.conf to include the VGA=ASK
paramater, and run lilo, this is required in order for you to be able to
select the modes you wish to use.
Reboot the kernel, and as a simple test, try entering 0301 at the VGA
prompt (this will give you 640x480 @ 256), and you should be able to see a
cute little Penguin logo.
4. What VESA modes are available to me?
This really depends on the type of VESA 2.0 compliant graphic card that
you have in your system, and the amount of video memory available. This is
just a matter of testing which modes work best for your graphic card.
The following table shows the mode numbers you can input at the VGA prompt
(actually these numbers are plus 0x200 to make it easier to refer to the
table)
bpp 640x480 800x600 1024x768 1280x1024 1600x1024
----+---------------------------------------------
256 | 0301 0303 0305 0307
32k | 0310 0313 0316
64k | 0311 0314 0317
16M | 0312 0315 0318
[The author would be happy if you could supply him with additional 03xx
numbers for additional modes]
5. Miscellaneous
This is current only for v2.1.111 of the Linux kernel. This HOWTO will be
constantly updated as kernel development progresses. Feel free to email
the author with information/flames :o)
Cheers,
Alex
-- /\_/\ Legalise cannabis now! ( o.o ) Grow some cannabis today! > ^ < Peace, Love, Unity and Respect to all.http://www.tahallah.demon.co.uk
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