Re: Issues with GRUB-gfxboot

[J. Silverman]

Hi Vesa,

Thank you very much for taking a look at the files! As far as the problem, I 
have been just informed that the person who originally patched Debian GRUB 
used a now older version of gfxboot, and that the newer version should have 
fixed some of the issues with the code.  Like I mentioned in a previous 
email, one of the developers is going to test Suse on vmware, but now we'll 
see if the new version has fixed some of these issues.  If it has, we'll go 
ahead and patch GRUB with a new gfxboot and use the new gfxboot utils.

Thanks again,
JS


----Original Message Follows----
From: chaac <address@hidden>
To: "J. Silverman" <address@hidden>,  address@hidden
Subject: Re: Issues with GRUB-gfxboot
Date: Mon, 22 Mar 2004 00:02:29 +0200


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

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