Is it possible to issue a VBE3.0 call from Grub (1.95) to set desired refresh rate?

Is it possible to issue a VBE3.0 call from Grub (1.95) to set desired refresh rate?

[Dimitry Golubovsky]

Hi,

I am using Linux 2.6 on x86-64 with framebuffer console, VIA Unichrome
integrated graphics chip on a VIA K9MM-V motherboard.

When the videomode is set using Linux kernel boot options
(video=vesafb vga=...), default refresh rate is 60Hz which causes
visible blinking on a CRT monitor. The vesafb-tng driver does not work
in 64 bit kernels. Kernel framebuffer driver modules specific to VIA
Unichrome were tried, but none worked.

Is setting a videomode via VBE3.0 call 4f02h with desired refresh rate
possible from within Grub - using the grub.cfg file, or with some
programming?

Another thing, how to pass parameters to Linux kernel so that it does
not attempt to change the video mode when loading the vesafb
framebuffer driver?

Video mode needs to be set just once, during the boot process.

Thanks.

PS I am completely new to Grub, but familiar with low-level programming.

-- 
Dimitry Golubovsky

Anywhere on the Web

Re: Is it possible to issue a VBE3.0 call from Grub (1.95) to set desired refresh rate?

[Robert Millan]

On Tue, May 29, 2007 at 10:03:35AM -0400, Dimitry Golubovsky wrote:
> Hi,
> 
> I am using Linux 2.6 on x86-64 with framebuffer console, VIA Unichrome
> integrated graphics chip on a VIA K9MM-V motherboard.
> 
> When the videomode is set using Linux kernel boot options
> (video=vesafb vga=...), default refresh rate is 60Hz which causes
> visible blinking on a CRT monitor. The vesafb-tng driver does not work
> in 64 bit kernels. Kernel framebuffer driver modules specific to VIA
> Unichrome were tried, but none worked.
> 
> Is setting a videomode via VBE3.0 call 4f02h with desired refresh rate
> possible from within Grub - using the grub.cfg file, or with some
> programming?

I'm not familiar with the video API either, but vbe.c:grub_video_vbe_init()
looks like a good place to start digging for the information you want.

grub_video_vbe_fini() might also be useful.

-- 
Robert Millan

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