Re: Framebuffer address and kernel video mode

[Colin D Bennett]

On Thu, 05 Feb 2009 21:44:59 +0100
phcoder <address@hidden> wrote:

> Hello. First of all some good news: I managed to boot xnu kernel. To do 
> so I need to set it to video mode and pass video mode info to kernel. 
> Now I do it in adapter-specific way which is bad and ugly. So I would 
> like to propose an interface to set video mode before loading kernel and 
> then retrieve information:
> For this I propose to put grub_gfxterm_init lines 253 (modevar = 
> grub_env_get ("gfxmode"))-482 (grub_video_fill_rect (...)) into video.c as
> grub_video_setup_by_var (char *varname)
> The informations I need is:
> 
> framebuffer address, bytes_per_scan_line, resolution, color depth
> 
> Unfortunately framebuffer_address and bytes_per_scanline is missing from 
>   struct grub_video_mode_info. I propose to add it to this structure
> 
> Thanks
> Vladimir 'phcoder' Serbinenko

Well, we could do this, but I don't really like the idea of making
framebuffer address and bytes_per_scan line parts of the generic video
API.

I think it would be OK to make these data accessible as an optional
feature.  That is, potentially future video drivers might not use a
framebuffer. (OpenGL driver? :-)  The VBE driver can return the
framebuffer address, but if another driver can't provide it, then maybe
NULL is returned instead, and this would have to be handled by clients
of the video API.

Regards,
Colin

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