On Fri, Oct 26, 2001 at 01:48:17PM -0400, Noah Meyerhans wrote:
| On Fri, Oct 26, 2001 at 12:00:53PM -0400, dman wrote:
| > | What other step(s) am I misssing?
| >
| > Add "vga=0x31A" to your kernel command line. This will give you
| > 1280x1024x16. See the docs for the values of the other modes.
| >
|
| I don't think that parameter affects the framebuffer, though. That is a
It does, see below.
| a VGA mode setting, and you can have a VGA text console without enabling
| a framebuffer. Framebuffer parameters look something like
| "video=tdfx:1024x768".
Supposedly that's what you do for the accelerated framebuffers
(matrox, etc) but that doesn't seem to work for vesafb.
| See Documentation/fb/modedb.txt in your kernel
| source tree. Docs for what you're describing are in
| Documentation/svga.txt, and that exists independently the
| framebuffer support in the kernel.
|
| I suppose I could be wrong, as I've only recently started playing
| with the framebuffer, but I know that you could pass 'vga=xyz'
| options to the kernel long before framebuffer support existed.
Yeah -- some numbers are for VGA text modes and some are for the VESA
framebuffer.
Here's a section of
/usr/share/doc/kernel-doc-2.4.8/Documentation/fb/vesafb.txt.gz :
-----------------------
How to use it?
==============
Switching modes is done using the vga=... boot parameter. Read
Documentation/svga.txt for details.
You should compile in both vgacon (for text mode) and vesafb (for
graphics mode). Which of them takes over the console depends on
whenever the specified mode is text or graphics.
The graphic modes are NOT in the list which you get if you boot with
vga=ask and hit return. The mode you wish to use is derived from the
VESA mode number. Here are those VESA mode numbers:
| 640x480 800x600 1024x768 1280x1024
----+-------------------------------------
256 | 0x101 0x103 0x105 0x107
32k | 0x110 0x113 0x116 0x119
64k | 0x111 0x114 0x117 0x11A
16M | 0x112 0x115 0x118 0x11B
The video mode number of the Linux kernel is the VESA mode number plus
0x200.
Linux_kernel_mode_number = VESA_mode_number + 0x200
So the table for the Kernel mode numbers are:
| 640x480 800x600 1024x768 1280x1024
----+-------------------------------------
256 | 0x301 0x303 0x305 0x307
32k | 0x310 0x313 0x316 0x319
64k | 0x311 0x314 0x317 0x31A
16M | 0x312 0x315 0x318 0x31B
To enable one of those modes you have to specify "vga=ask" in the
lilo.conf file and rerun LILO. Then you can type in the desired
mode at the "vga=ask" prompt. For example if you like to use
1024x768x256 colors you have to say "305" at this prompt.
If this does not work, this might be because your BIOS does not support
linear framebuffers or because it does not support this mode at all.
Even if your board does, it might be the BIOS which does not. VESA BIOS
Extensions v2.0 are required, 1.2 is NOT sufficient. You will get a
"bad mode number" message if something goes wrong.
1. Note: LILO cannot handle hex, for booting directly with
"vga=mode-number" you have to transform the numbers to decimal.
2. Note: Some newer versions of LILO appear to work with those hex values,
if you set the 0x in front of the numbers.
-----------------------
Now you don't need to hunt it down in the docs yourself :-).
-D
