Re: framebuffer console problems: not enough video RAM?

Ray Olszewski
2004-10-23T22:17:51Z

At 03:06 PM 10/23/2004 -0500, James Miller wrote:
>Latest on this problem is that I'm using only the video=atyfb:102x768-8@75
>argument (no vga=xxx argument) in menu.lst. During the boot process the
>screen goes black for a time--with just a cursor at the very bottom, which
>starts scooting back and forth horizontally--then comes back just as it
>was at a 640x480 resolution. Boot process continues and gdm fires up. In
>all this fiddling around, I've somehow gotten fbset to work--maybe by
>adding atyfb to /etc/modules. When I run fbset (no options) it tells me
>the console is set to 640x480-60. Trying to reset it to 1024x768-75--or
>any other of the 1024x768 or 1280x1024 settings I've tried--makes the
>console go black and the "vga mode not support(ed)" message appear on it.
>Reading some further info on the web, I decided to try issuing some
>resolution setting options separately with fbset--i.e., specifying just
>the V or H resolutions. yres at 768 "works" although the screen goes
>blank. When I try to set xres at 1024, I get an IOCTL error though. When
>I check dmesg output afterwards, I see "kernel: not enough video memory."
>Is my problem therefore--with atyfb just as with vesafb--not enough video
>memory to do 1024x768? I would have guessed 8MB would suffice, but that's
>just a layman's conjecture. I actually have 12MB--added an 8MB SGRAM
>module where a 4MB one was supposed to go--but BIOS seems only to see 8
>and that's what dmesg reports too. So, is this the inglorious end of all
>this researching and tweaking? Feedback appreciated.

One more thought: although the spec for setting video mode looks like you
can put in any old values, in fact you have to use a mode that the kernel
source understands. I don't have a 2.6.x source tree handy, but 2.4.21
doesn't include any 1024x758-b@75 choices. The only entries I can find for
1024x768 in that source are:

/* 1024x768 @ 87 Hz interlaced, 35.5 kHz hsync *
/* 1024x768 @ 60 Hz, 48.4 kHz hsync */
/* 1024x768 @ 70 Hz, 56.5 kHz hsync */
/* 1024x768 @ 76 Hz, 62.5 kHz hsync */
/* 1024x768 @ 85 Hz, 70.24 kHz hsync */
/* 1024x768 @ 100Hz, 80.21 kHz hsync */

So if your LCD panel will support multiple refresh rates, try picking from
the choices listed above. Or get the kernel source and look in
./drivers/video/modedb.c to see what is available in your 2.6.x kernel.