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List:       gentoo-dev
Subject:    [gentoo-dev] Fwd: Re: grub-0.5.97-vga16.patch
From:       Donny Davies <woodchip () gentoo ! org>
Date:       2001-08-28 14:21:01
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Hi, devs

Im forwarding this response I got from the author of the grub
vga splashimage stuff.  Edited for clarity.

--
Woodchip

----------  Forwarded Message  ----------

Subject: Re: grub-0.5.97-vga16.patch
Date: Sun, 26 Aug 2001 19:22:22 -0300 (BRST)
From: pcpa@conectiva.com.br
To: Donny Davies <woodchip@gentoo.org>

Cópia Donny Davies <woodchip@gentoo.org>:
> Hi!

  Hi Donny

> Recently our distribution (http://www.gentoo.org - #gentoo on
> openprojects) added grub-0.90 to our portage tree.  The boot graphic
> stuff is I think working well for many people, and I guess we have
> you to partially thank for that. Thanks!
>
  :-)
>
> But the real reason Im mailing you, is when I use it on my notebook PC
> (Toshiba Satellite Pro, 4330CDX) I get corruption on the screen
> wherever text is supposed to appear.
> A couple points.. The splashimage shows up perfectly.  I can see our
> graphic and it looks very nice.  But where there is supposed to be text
> like the title= lines, etc, and the ___ | characters (the "box" that
> surrounds the menu choices), there is only "snow", like its
> somehow getting corrupted.  I hope you know what I mean.. I cant
> explain it clearer than that.

  Maybe your notebook bios does not have memory reserved for the
vga characters, I guess it probably stores the fonts in the graphics
memory, and is being overwritten by the splashimage. It may also be a
bug in the bios implementation, but I don´t discard a bug in the grub
patch (that happens with your bios), when calling the bios interrupt that
should return a pointer to the characters.
   At some time, I was thinking about adding a option for reading a console
font file from the unix filesystem, maybe the problem you are describing is
good motive to add such option.

> The video chipset is a Chips & Technologies 65554 PCI video chipset,
> which is a nice little 2MB video system with support for 24bit color.
>
> I have in the past (not any more!) used a bootloader from PowerQuest
> (BootMagic) that displayed nice boot graphic.. please dont think Im
> saying
> your patch is bad, and powerquest is good, Im just saying that I know
> it
> too had to draw text to the screen (I could supply strings to the
> program)
> which it displayed inside its fancy bootimage.  So I think the problem
> is
> not with my video chipset, but with some code in grub somewhere.
>
> Also, the way it comes up now, there is black space on all sides.  The
> main image is "squished" into the middle of my notebook screen, it
> doesnt
> take up the whole screen space.  The bootlader from PowerQuest took up
> the whole screen, so again, I think grub could be improved there too.

  This happens because the grub code, actually, only works in vga 16 colors,
and it only runs at 640x480. In my grub TODO list is to add support for
VESA modes, that would allow running at any resolution and number of colors.

> Another point I wanted to make, was that MS Windows splash screens on
> my
> notebook, also get "squished" into the middle of the screen, leaving
> black
> space on all sides.  Im only telling you this in hopes that it will
> be useful to you for debugging.  Maybe this information is good for you to 
> consider, maybe you dont care about windows or powerquest, thats fine
> with me!

  I know about what you is talking, and it is a very useful information,
I won´t say I will work on improving grub soon to fix the problems you
described, but it is now in my todo list...

> I would be *very* happy to help you in any way possible.  I can usually be
> found in #gentoo on openprojects.net, with the nickname "woodchip".  If yuo
> want to get together, and see if we can debug the issue, I will certainly
> help you.  However I am not a master with debugging tools like gdb
> and stuff, so it might be a little slowgoing.

  gdb won´t help in debugging grub, you probably better with the
printf/getkey functions in grub...

> The "squished" thing might not be a big priority to you, and thats
> also fine by me, but I think that the "corruption where text should be" is
> a good thing to work on, because other people will likely have the same
> problem, not just myself.

  If you wish to work on grub, and has some priority on it, I suggest
writting code to load console fonts from the filesystem (or compile a static
copy of the vga fonts in grub). Also, if you are going to look at it, I
believe there is a problem with the interrupt for blinking the cursor. I
think it is required C functions to disable/enable cursor blinking, as I
think this is the cause of some screen corruptions that may happen when doing
some long operation, like loading the kernel or initrd, or just installing
grub in the partition.

> --
> Cheers, and have a great day!
> Donny

Paulo

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