[TF-A] About the SDS usage model

Hi all,

I am trying to raise a question about SDS.

As you know, SDS (Shared data storage) is used to communicate or exhcange info among different processor units like AP, SCP, RSE, etc.

So, do we need to add some lock mechanisms to protect the data when one processor entity is accessing it? After I reviewed the open source Trusted Firmware and SCP firmware

it looks to me that both Trusted Firmware and SCP directly access the shared memory region without any limitation. Currently, it just uses the 'valid' flag to identify if the data is ready to use,

is this good enough?

Looking forwared to your response! Thank you!!!

Best Regards,

Bob