[U-Boot] environment expectations of config_distro_bootcmd.h

[Ian Campbell]

Is there any documentation as to what environment variables a platform
must provide if it uses config_distro_bootcmd.h. ${scriptaddr} seems
clear but what about e.g. kernel_addr_r and friends? I suppose the use
of the pxe commands has some implicit dependencies (pxe_addr_r?)

Along the same lines is there any documentation regarding which
variables a boot.scr which expects to be called via this mechanism can
rely on. e.g. devtype/devnum/bootpart/prefix etc. Also foo_addr_r again
I suppose?

There is some info in the README but it says things like "these
variables don't have to be defined for all boards" and worse "some
boards use these variables for other purposes." ;-)

Thanks,
Ian.