As I mentioned in another comment, 2GB is the maximum memory size that all of the processors within the SOC can access, so it's a perfectly reasonable amount of

As I mentioned in another comment, 2GB is the maximum memory size that all of the processors within the SOC can access, so it's a perfectly reasonable amount of RAM to spec for this SOC. The Cortex-A CPUs can access more than 2GB but because that memory requires more than 32 bit addressing, the other processors cannot easily access it. This is a common theme in similar TI SOCs. For example, the AM57xx SOC which are used on the Beagle-X15 and Beagle-AI can have more memory available to the Cortex-A15 than can be possibly made available to the DSP and Cortex-M4 processors. The Cortex-A15 has a special interface to the memory controller which enables extended address use beyond 32 bits where-as the other processors and subsystems within the SOC are all attached to a bus where 32 bit addresses are the maximum.