Re: can I use video=imsttfb? [was: what is the video=ofonly kernel argument]
On Wed, Oct 02, 2002 at 11:47:18AM +0200, Vinai Kopp wrote:
> On Tue, Oct 01, 2002 at 10:51:39PM -0500, Michael Heironimus wrote:
> > On Tue, Oct 01, 2002 at 11:52:46PM +0200, Vinai Kopp wrote:
> > > I finally got the console to work using the "video=ofonly" kernel
> > > arguments.
> > > But what do they mean? I tried to figure it out looking at the fb/*
> > > sources, but they are a bit beyond my humble capabilities. Can it be
> > > explained to someone as ignorant as me?
> >
> > I'm not a real expert either, but my understanding is that the ofonly
> > driver accesses the video in a generic Open Firmware manner, which gives
> > you no acceleration or other features but will work on pretty much any
> > OF Mac. Since it doesn't use any hardware-specific driver, you can use
> > it when your internal video is unsupported or when the drivers (or
> > hardware) is buggy, but you sacrifice any hardware-dependent features at
> > the same time. You also can't change resolutions on the fly, you're
> > limited to whatever OF thinks your video is set to (usually whatever it
> > was in the last time you booted to Mac OS).
>
> Thanks for the awnser. That is about what I guessed it would be. :)
>
> Now, would it be possible to specify this:
>
> video=imsttfb:vmode:?,cmode:24
>
> And what vmode would/could I specify?
> I am guessing this on what I read in the bootpromt howto and in
> imsttfb.c, but I could likely be dreadfully wrong. Any pointers in the
> right directions are very appreciated!
This is the 9600, right? According to macframebuffer.html which I
downloaded from somewhere, that should be and ATI Mach64 (you could
verify with cat /proc/pci). So then you should be using atyfb, not
imsttfb:
SYNTAX
video=xxxxx:vmode:vv,cmode:cc r
where xxxxx should be replaced with something appropriate for the frame buffer
of your video card or built-in video chipset, vv and cc should be replaced with
a vmode and cmode, respectively, that are supported by your monitor. r is
optional, and can be replaced with an appropriate run-level. See below for
examples of these values.
VMODE
vmode refers to both the screen size in pixels (horizontal x vertical) and the
refresh rate (in Hz).
vmode size(pixels) refresh notes
----- ------------ ------- -----
1 512 x 384 60 Hz Interlaced NTSC
2 512 x 384 60 Hz
3 640 x 480 50 Hz Interlaced PAL
4 640 x 480 60 Hz Interlaced NTSC
5 640 x 480 60 Hz
6 640 x 480 67 Hz
7 640 x 870 75 Hz Portrait
8 768 x 576 50 Hz Interlaced PAL
9 800 x 600 56 Hz
10 800 x 600 60 Hz
11 800 x 600 72 Hz
12 800 x 600 75 Hz
13 832 x 624 75 Hz
14 1024 x 768 60 Hz
15 1024 x 768 72 Hz
16 1024 x 768 75 Hz
17 1024 x 768 75 Hz
18 1152 x 870 75 Hz
19 1280 x 960 75 Hz
20 1280 x 1024 75 Hz
CMODE
cmode refers to the bit depth and will be either 8, 16, 24, or 32 (though 24
and 32 might actually produce the same result). To convert bit depth into
number of colors simply find 2^(bit depth). So an 8-bit display will have 2^8
or 256 colors, while a 24-bit display will have 2^24 or 16,777,216 colors
(millions of colors).
This document is: <a href="http://www.jonh.net/cgi-bin/lppcfom/fom?file=1043";>http://www.jonh.net/cgi-bin/lppcfom/fom?file=1043</a>
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