Hi Patryk,

On Thu, 21 Nov 2024 at 14:47, Patryk pbiel7@gmail.com wrote:

Hello, I've been currently looking at the possibility of storing u-boot environment variables in RPMB and I've stumbled upon this article: https://www.linaro.org/blog/protected-uefi-variables-with-u-boot/ which briefly describes what needs to be done in order to achieve this. Unfortunately there is no comment section in this article so I cannot ask the author so I decided to try here. The article mentions that for that purpose, my board should support dynamic shared memory, therefore the OP-TEE port for my board should register that memory in platform main using the "register_ddr" function. For my platform (ls1028ardb) I do not see anything like this, thus I assume it's not supported. However, I'm wondering - is it my platform's hardware limitation or missing software implementation?

A software implementation issue

Making this question more generic - does dynamic shared memory depend on hardware, meaning that there is no way to register dynamic shared memory if hardware does not support some particular features? I would be grateful for some hints.

You can define all of your available DDR as shared memory. That's merely a check in OP-TEE for what memory we can use. Someone correct me if I am wrong but simply defining the entire memory shouldn't be a problem

Keep in mind that there was a breakage in StMM [0] which hasn't been fixed yet, so you will need to clone an older version of EDK2 for now

[0] https://lore.kernel.org/linux-efi/CAC_iWj+4G3LG0XpsygS+MYJU9+oPhftOnPAfkOnEg...

Cheers /Ilias

Best regards Patryk