There are many open source bootloaders available today. Almost all of them have features to load and execute a program, which usually involves the operating system, and its features are used for serial interface communication. However, not all of them have the possibility to communicate over Ethernet or update themselves. Another important factor is represented by the widespread use of the bootloader. It is very common for organizations and companies to choose only one bootloader for the diversity of boards, processors, and architectures that they support. A similar thing happened with the Yocto Project when a bootloader was chosen to represent the official supported bootloader. They, and other similar companies, chose U-Boot bootloader, which is quite well known in the Linux community.
The U-Boot bootloader, or Das U-Boot as its official name, is developed and maintained by Wolfgang Denx with the support of the community behind it. It is licensed under GPLv2, its source...
