Customizing das U-Boot

[Tobias]

Hello,
I try to customize das U-Boot from STM32CubeIDE project.
Compiling the base examples is working fine now and even exporting the dts/dtsi files and compiling this ends in a booting stm32 file.

But what I really want to do is changing the RAM which can be seen in Linux.
I changed the reserved-memory block by adding a new entry
cpu_memory:cpu@0xd0000000{
reg = <0xd0000000 0x04000000>;
no-map;
status = “okay”;
};
What I expected is there are 64MB of contiguous memory reserved beginning at the address 0xd0000000.
But top do not change the available memory and even worse a normal user can access this area which I checked using a simple c++ program that fills the ram with known values until it crashes and start it again.
For the first addresses this seems to work but there are regions which contain these data.

A second thing I tried is change the amount of memory defined for the gpu.
But the same behavior is happening.

Is there anything I am missing?

Thank you

[Neeraj Dantu]

Tobias,

RAM access can be controlled via TZC (Trust Zone Controller). Please take a look at the wiki page here: https://wiki.st.com/stm32mpu/wiki/TZC_internal_peripheral. Also see Section 6 of the reference manual for configuration: https://www.st.com/resource/en/reference_manual/DM00327659-.pdf.

Best,

Neeraj

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