The BSP that encapsulates the hardware modifications for a given platform is mostly located in the bootloader, usually U-Boot (Das U-Boot) for ARM devices, and the Linux kernel. Both U-Boot and the Linux kernel have upstream development trees, at git.denx.de and kernel.org respectively, but it is very common for manufacturers of embedded hardware to provide their own trees for both bootloader and kernel.
Development in U-Boot and the Linux kernel is usually done externally to Yocto, as they are easy and quicker to build using a cross-compilation toolchain, like the one provided by Yocto's SDK.
The development work is then integrated into Yocto in one of two ways:
- With patches added to the kernel and U-Boot bbappend files. This method will build the same source as the reference design board we are using as a base, and apply our changes...
