Slidepad 704ce - Modify the Bootloader (boot logo, ...)



When doing some tweaks on your android device, you may need to change some parameters on the bootloader, for example the first boot logo (the second one is in the root filesystem).

The bootloader filesystem in a vfat filesystem and it is recorded in /dev/block/nanda.

This article will explain all the steps to make permanent changes to your bootloader :

  1. extract bootloader image from Slidepad 704ce
  2. mount it as a vfat filesystem
  3. change the boot logo (for example)
  4. unmount the vfat filesystem
  5. flash back the updated bootloader on the device

It has been specifically designed for Slidepad 704ce, but it should be applicable to many devices powered by A10 or A13 Allwinner SoC.

Your tablet should run ICS or JB and should be fully rooted. If it's not the case ... follow the guides :

Whole procedure is designed to be done from a Ubuntu computer. Any other Linux flavour should be fine.

All following commands have to be run from your computer with your tablet connected with USB Debug on.

This article is only for advanced users. You really need to know what you are doing if you want to follow this procedure.
If you only need a rooted tablet with Google apps, you don't need to follow all these steps and to go further.

1. Extract Bootloader & Mount Filesystem

All following commands have to be run from your computer with your tablet connected with USB Debug on.

On Slidepad 704ce, bootloader image is available under /dev/block/nanda.

First step is to extract bootloader image from the tablet :

# adb shell su -c "cat /dev/block/nanda > /mnt/sdcard/nanda-bootloader.img"
# adb pull /mnt/sdcard/nanda-bootloader.img
4017 KB/s (16777216 bytes in 4.078s)

We can now mount the filesystem under a bootloader directory :

# mkdir bootloader
# sudo mount -t vfat ./nanda-bootloader.img bootloader

The complete bootloader file structure is now available in your current bootloader directory.

2. Modify the Bootloader files

You can now modify whatever file you want within this directory structure.

Whatever you'll modify has to de done as root (sudo ...).

If you want to change the bootloader logo, the file is linux/linux.bmp. On Slidepad 704ce (and I suppose also on other A10 and A13 tablet), the logo is RGBA 32bits BMP file.

The easiest to create a new logo is to use GIMP and to create a 800×480 PNG file with a transparency layer. The transparency layer is very important as it will indicate to generate a 32bits BMP during conversion process.

When your linux.png logo is ready, we need to convert it and to place it back in the file structure.

imagemagick will be used for the conversion :

# convert linux.png linux.bmp
# sudo cp linux.bmp ./bootloader/linux

You new logo is ready for flashing.

3. Flash back the new Bootloader

Before being flashed back, the new bootloader image needs to be unmounted. It can then be flashed back to your tablet.

Don't make any mistake, be sure to target nanda or your tablet may get into trouble !

# sudo umount bootloader
# adb push nanda-bootloader.img /mnt/sdcard
4389 KB/s (16777216 bytes in 3.732s)
# adb shell su -c "cat /mnt/sdcard/nanda-bootloader.img > /dev/block/nanda"
# adb shell rm /mnt/sdcard/nanda-bootloader.img
# adb shell su -c "sync"
# adb shell su -c "reboot"

Your tablet will now reboot with your updated bootloader.

Cross fingers ... and enjoy !


Hope it helps.

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This article is published "as is", without any warranty that it will work for your specific need.
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