Vastly generalizing things, mobile devices have two bootloaders—a primary bootloader and a secondary bootloader. While many devices obtain S-Off via replacing the secondary bootloader, not every device receives a completely customized secondary bootloader to replace the factory offering. Luckily, however, the Barnes & Noble Nook Tablet is now one of those lucky few.
XDA Recognized Developer fattire has released a secondary bootloader dubbed CyanoBoot. The bootloader itself is based on the open source U-Boot project that was then customized by XDA Forum Member Bauwks. In the words of the developer:
CyanoBoot (working title) is a “second bootloader” in early development, which is based on the open-source “u-boot” project, as further customized by BN & Bauwks. It is similar to the bootloader provided by Bauwks but has additional enhancements to make booting unsigned partitions easier and to generally enhance the booting experience on the Nook Tablet (aka “acclaim”) device.
There are also a whole bunch of features, including:
Started with “UB1” (aka u-boot, “first boot”) source code
Includes changes to support new 512MB model
Includes Bauwks’ repairs to fix “locked bootloader” malware
Many duplicate UB1 functions removed
One-build-boots-all (emmc or SD card, custom OS or stock)
Boot device indicator (top-left corner)
Bootcount indicator (top-left corner)
On-screen feedback to let you know what it’s loading.
Console-based boot menu
Support for key-combo shortcuts for menu/recovery
Alternate “Altboot” multiboot support allows 2nd OS.
Emmc setting for default boot profile (normal/altboot)
Emmc setting for default boot device (emmc or sd)
Emmc setting for automatic bootcount clearing
Boot fallback for stock firmware (0 bytes + sec. header)
Boot fallback for bauwks’ uboot (256 bytes)
Numerous visual enhancements
Unused bulky images removed (smaller file)
FASTBOOT support (w/menu selection)
On-screen build timestamp so you know version
Now, the important thing to remember is that it’s still in a very early beta stage so many of these features may have bugs so it’s very important to not attempt unless you’re a developer looking to help out or you’re comfortable enough with the risks to flash it, which can include bricking the device entirely.
CYANOBOOT (WORKING TITLE) IS HIGHLY EXPERIMENTAL AND IS NOT INTENDED TO BE USED BY NON-DEVELOPERS AND/OR THOSE UNWILLING TO ACCEPT FULL RESPONSIBILITY FOR ANY UNTOWARD CONSEQUENCES OF USING (OR ATTEMPTING TO USE) THE SOFTWARE. ALL SUCH ACTIVITY MUST OCCUR *ENTIRELY AT YOUR OWN RISK* AND YOU ACCEPT ALL CONSEQUENCES FOR DOING SO
For those feeling particularly brave and don’t mind that they’re doing this at their own risk, or for developers who want to help you, you can check out the original thread for what amounts to a short novella of information—including what it is, how to use it, feature list, download links, and of course, the shout outs and thank yous._________