Why the RSB?
The RSB history explains why the RPM spec file format was used. It is historical. The RSB manages a complex matrix of the packages you want to build, the host you are using and any sources and patches that package, host or package on a host needs.
The RTEMS Project deals with building from source. In the past we built RPM files (and more) and in the end we found the focus of the project became distro packaging and not a real-time operating system and eco-system. There are so many distros and operating systems, more than we can handle.
We have now started to define deployment you can use to assist with deploying RTEMS for your project, company or universe. There is no single deployment model that suites everyone so we provide tools to let you deploy RTEMS in a way that bests suites you.
There is another more subtle factor at work here. A ready to go prebuilt OS and tools for your hardware lets you start and get working quickly. The endorphins that gives is fantastic. RTEMS is a bit slower to get up and running so that intial hit may not be present but what you get and earn once you have “Hello World” running is the complete source code for every part of the tools and OS. You have solved the project archive for long term maintenance as you start. You can develop your project and once done archive it and you know you have everything