Subject: Re: 2.1 W/ Radeon
From: Patrick Callahan (pac1@tiac.net)
Date: Sat Oct 27 2001 - 04:41:22 MDT
On Thursday 25 October 2001 10:49, you wrote:
> More problems.. I was able to get fbset -accel working by appending true to
> it so it goes
> fbset -accel true
> The depth part is another story I got
> fbset -depth 16
> ioctl FBIOPUT_VSCREENINFO: invalid argument.
>
The message is from ioctl, the low level routine that is probably trying to
set some value in your video card. The question is what value and where did
it get it.
I did some more poking about on fbset.
I had recalled using fbset to try out all the different modes, refresh rates
and bit depths I could come up with for my monitor. Some of them worked,
some did not. I never knew why.
I'm beginning to get a clue. The fbset sources from the YDL2.1 CD contain a
configuration file for fbset:
ls fbset-2.1/etc
CVS fb.modes.ATI fb.modes.Falcon fb.modes.NTSC fb.modes.PAL
Here's some guesses about what is going on. I hope they're intelligent but
you never know.
I think these contain the description of the various modes available for
setting up the frame buffer device. If that's true, you can select one of
the using a command like this:
fbset 1024x768-75 -depth 16
You can use grep "modes " /etc/fb.modes to get a list to try with various
depth parameter values. If 16 doesn't work try 24 or 32. Not all
combinations work on an ATI Rage Orion, but I found the one listed above to
be comfortable so I use it.
One or more of the source files in fbset-21./etc are used to produce
/etc/fb.modes
Its the modes in /etc/fb.modes that I scanned through with fbset, searching
for one I liked, but I have an ATI card, not a Radeon. does there need to
be a different fb.modes for Radeon? or does one of the fbmodes in the ATI
file happen to work for Radeon?
Notice that all I seem to be doing by selecting a given resolution and
refresh rate is picking a pre-calculated set of information for the frame
buffer device that I assume it will use to communicate with the video card
and the monitor attached to it. Since I'm using an ATI card, this works for
me. Your mileage seems to vary.
Just what is the "frame buffer device" anyway? Isn't it an abstraction of
video cards?
Someday I have to read the frame buffer howto...
-Pat
This archive was generated by hypermail 2a24 : Sat Oct 27 2001 - 03:51:30 MDT