kernel/color depth problem

kernel/color depth problem

Post by Marc Shapir » Fri, 23 Jun 2000 04:00:00

I had been running LinuxPPC 1999Q3 for several months with no problems.
I recently deleted my LinuxPPC kernel by mistake, and since then have
not been able to find one that works correctly.  My most recent attempt
has been with 2.2.15pre19 precompiled from Paul McKerras' site.

With this kernel (as well as with other recent kernels that I tried)
video does not work correctly: when running X, I get ugly horizontal
streaks across the screen every ~10 pixel rows or so, the colors are
ugly, and the screen background is strangely pixellated.  I think the
problem is that the video driver is only seeing part of the video
memory.  This is a transcript from running fbset:

        # fbset

        mode "name"
            # D: 78.518 MHz, H: 59.846 kHz, V: 74.807 Hz
            geometry 1024 768 1024 8176 8
            timings 12736 160 32 28 1 96 3
            hsync high
            vsync high

        # fbset -depth 32
        ioctl FBIOPUT_VSCREENINFO: Invalid argument
        # fbset -depth 24
        ioctl FBIOPUT_VSCREENINFO: Invalid argument
        # fbset -depth 16
        ioctl FBIOPUT_VSCREENINFO: Invalid argument
        # fbset -depth 8

As you can see fbset thinks there is only 8 bits video memory, whereas
my machine supports 32.  Indeed, if I reboot under MacOS I can access
millions of colors; and if I reboot under an older kernel, fbset reports
a video depth of 32 and none of the above problems occur.

Strangely, a friend of mine has an apparently identical configuration
but he sees none of these problems.  Another strange thing is that when
the X server starts, the background first comes out fine, then it seems
to change its mind and do the ugly pixellation.

My machine is a Powerbook G3 series (Bronze keyboard) with 128 Mb RAM
and 8 Mb video memory.  The video card is LTPro-parent (this information
from Apple's System Information application).  I boot with BootX 1.2.2.
The "extra kernel arguments" are 'video=atybf:vmode:14,cmode:32'.  The
problems occur whether 'No video driver' is checked or not.  Under MacOS
the screen is set to 1024x768, millions of colors.

Any help with this problem will be appreciated.  Please answer by
e-mail.  Thanks.



1. Kernel Color Depth Problem

Hello, I recently upgraded my kernel from the original 2.2.15pre3 that
came with LinuxPPC 2000 (Q1), and now all of a sudden, I can't go higher
than 8-bit color.  I've tried setting it under MacOS, which doesn't work,
and I've also tried the vmode command.  When I enter the settings and
startx, it just uses 8-bit color, even though I told it to do 24.  I'm
using BootX, kernel 2.2.18-5 (I know there are newer kernels, but that's a
whole nother story), and it doesn't appear to matter whether or not I
check "No Video Driver" or not.

Any help would be great,

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