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This directory contains examples of the new-style BIOS bitmaps, and a simple
(and ugly) tool to view the configuration file that describes how each
screen is displayed.
Old-style bitmaps:
In the Cr-48 BIOS there are four BIOS screens that may be presented to the
user. Each contains a graphic, a URL, and some informative text. The screens
are single bitmap images, hardcoded in read-only BIOS (because they have to
display even when the R/W BIOS and SSD are both completely erased). They can
be replaced at manufacturing time, but creating the screens is difficult.
The format is a compressed EFI firmware volume that is generated when the
BIOS is compiled. The result is an opaque blob that cannot be viewed or
edited with linux-based tools.
New-style bitmaps:
Future BIOSes will continue to display the same basic screens, but using a
different format. Each screen will have separate bitmaps for the basic
graphic, the URL, and the informative text, and will be displayed by
rendering each component in order. This will allow us to modify and replace
any bitmap (most frequently the HWID), using standard command-line tools
such as imagemagick. Compositing each screen in this way also means that we
can easily provide localized BIOS screens or custom messages.
Because the bitmap images and display code is part of the Read-Only BIOS,
back-porting the new-style bitmaps to older devices is not possible.
The bmpblk_utility reads a config file and produces a binary bmpblock. The
config file lists the individual bitmaps and describes where to place each
one when displaying each screen. The bmpblock is then written into the BIOS
image with the gbb_utility. The bitmap_viewer program lets you view the
composited screens as described by the config file.
* First, get the bitmap_viewer working. This is best used OUTSIDE of the
chroot. Test it by changing to the scripts/newbitmaps/images/1280x800
directory and running "../../bitmap_viewer unknown.yaml". You may need to
install some additional packages. For example, on Ubuntu you'll probably
need to install the "python-yaml" and "python-wxgtk2.8" packages.
* Now make changes to the unknown.yaml config file, and use the
bitmap_viewer to see how the layout looks. Hit Ctrl-R in the small window
to reload the config file without restarting.
* The bitmap_viewer can display images in several different formats, but the
BIOS is very limited (and may differ between x86 and ARM). For x86, ensure
that you're using the proper format by converting any new bitmaps with a
command like this:
convert IN.bmp -colors 256 -compress none -alpha off OUT.bmp
* When you have the screens tweaked to your satisfaction, generate the
binary bmpblock to embed into the BIOS.
bmpblk_utility -c unknown.yaml bmpblock.bin
* Use the gbb_utility to modify the BIOS to contain our new set of bitmaps.
NOTE: These commands are run (as root) on the device under test!
NOTE: This will only work if the BIOS write-protection is disabled!
Copy our new bmpblock over.
cd /mnt/stateful_partition
scp USER@SOMEHOST:/SOMEPATH/bmpblock.bin .
Get a copy of the current BIOS.
flashrom -r bios.bin
Put our bmpblock in our copy of the BIOS
gbb_utility -s -b bmpblock.bin bios.bin
Reflash the BIOS with the new content
flashrom -w bios.bin
* Reboot. You should see your new bitmaps appear whenever the BIOS screens
are displayed. If you have more than one localization, you should be able
to cycle among them with the arrow keys.
* If you want to examine a binary bmpblock that you've pulled from a BIOS
image, the bmpblk_utility has options to display or unpack the binary.
bmpblk_utility bmpblock.bin
bmpblk_utility -y bmpblock.bin
bmpblk_utility -x -d /SOME/SCRATCH/DIR bmpblock.bin