Re: Issues with GRUB-gfxboot

[chaac]

J. Silverman wrote:

> Hi Vesa,
>
> Thank you for offering to take a look at the source code! The link to 
> the code is:
>
> http://neverborn.org/files/grub-gfxboot/
>
> The person who made the patch created a source and a binary directory.  
> In the .deb files under the binary dir, there are source files which I 
> use to create the "message" which is used to create the menu.  You might 
> want to look into that as well as the source code under the source 
> directory.
>
> Thanks again,
> JS

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......

But anyway. Some notes about for person fixing it:

- 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