Re: Issues with GRUB-gfxboot

[Hans-Peter Jansen]

On Sunday 21 March 2004 23:02, chaac wrote:
>
> Just looked at it. In actual patched grub there is no problem. But
> custom gfxboot utils that make actual image to be show on screen or
> what ever also it does. Actually this image seems to contain
> assembler made source code and grub stub just calls to code in
> image that is commanded to be loaded.
>
> As this file is in assembler and whole drawing to screen is spread
> all over the file I don't have _that_ much of time to fix it's
> problems. Maybe you could look for RedHat's version as that seems
> to be more compatible. But probably doesn't have that fancy MOD
> player......

Well, respecting the fact, that it's a postscript like interpreter, 
it's quite dense and very flexible..

> But anyway. Some notes about for person fixing it:

I just forwarded this to the responsible person.

> - get & read http://www.vesa.org/vbe3.pdf :)
>
> - VBE2/3 support can make your life easier when using linear frame
> buffer. Only really old cards supports only < VBE2. Of course you
> could also support banked modes.
>
> - make virtual screen buffer for storing on screen gfx.
>
> - make some functionality to draw that buffer to actual screen, to
> make it more easier to support multiple cards with different
> settings.
>
> - if that is not option, make sure when calculating position in
> screen to use formula (y * bytes in scan line) + x and _NOT_
> currently used (y * width) + x. And then set appropriate window
> segment.
>
> - DO NOT use set logical scanline length (some cards BIOS has bugs
> with it), instead use GET logical scanline length if needed and use
> that information when drawing to screen.
>
> Thanks,
> Vesa Jääskeläinen

Thanks for this very nice description.

Cheers,
Pete