grub-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: jpeg image does not show in background


From: Piscium
Subject: Re: jpeg image does not show in background
Date: Fri, 1 Oct 2010 19:55:34 +0100

On 1 October 2010 17:44, BandiPat <address@hidden> wrote:

> I don't think it's the monitor's resolution that you should be concerned
> with, but your graphics cards framebuffer.  Since the graphics card's engine
> hasn't been fully activated yet, you are relegated to the framebuffer only
> to display images.  Normally this will be 1280x1024 or smaller.

Well, 1920X1080 displays well with png with a file of 3.2 Mbytes.

> Have you tried a 1280x1024 size jpeg for your background image?

Following your suggestion I hacked grub.cfg to display 1280x1024. Then
I got two other images of this resolution, one png, one jpeg. The png
displayed well, the jpeg didn't.

At this point I thought that no jpeg could be displayed. To test this
hypothesis I started Gimp and created a basic jpeg, with some
scribbles with a red brush on a white background. The file was
obviously much smaller than the others I had tested, only 78 Kbytes.
This file displayed well.

The conclusion appears to be that the jpeg module in grub2 is very
fussy about the files that it displays. Note there was nothing special
about the files I wanted to display. The "green_mountains" was taken
from a blog, and the two 1280x1024 images were taken from the Gnome
Art website.

There is a file grub-core/video/readers/jpeg.c. It has plenty of debug
statements like:
    "grub_error (GRUB_ERR_BAD_FILE_TYPE, "jpeg: huffman decode fails");

Is there some easy way to read the text of these messages? (I have no
JTAG and my hardware does not support virtualization).



reply via email to

[Prev in Thread] Current Thread [Next in Thread]