Reducing OP-TEE RAM size on STM32MP157C-DK2

[AVazquez]

Hi everyone,

I'm working with the STM32MP157C-DK2 board and trying to reduce the amount of RAM allocated to OP-TEE, but so far I haven't been successful.

There are 32MiB DDR dedicated for OP-TEE. 30MiB for TZSRAM and 2MiB for SHMEM.

In OP-TEE sources I changed value for CFG_TZDRAM_SIZE to 16 MiB and I'm keeping the value for SHMEM.

In TF-a sources I changed value for DDR_SEC_SIZE to 16MiB.

In Device tree I changed total RAM dedicated for OP-TEE to 18MiB.

But when kernel start I have a fail:

Starting kernel ...

E/TC:0   
E/TC:0   Core data-abort at address 0x2fff8762 (translation fault)
E/TC:0    fsr 0x00000207  ttbr0 0x2ffe0000  ttbr1 0x00000000  cidr 0x0
E/TC:0    cpu #0          cpsr 0x600001f3
E/TC:0    r0 0x2fff8762      r4 0x2ffe1f71    r8 0x00000073   r12 0xe0000000
E/TC:0    r1 0x2ffe1f1c      r5 0x00000000    r9 0x00000000    sp 0x2ffe1e70
E/TC:0    r2 0x2ffd3355      r6 0x00000000   r10 0x2fff8762    lr 0x2ffcdf77
E/TC:0    r3 0x2fff8762      r7 0x2ffe1f71   r11 0x2ffe1f58    pc 0x2ffcd8f8
E/TC:0   TEE load address @ 0x2ffc0000
E/TC:0   Call stack:
E/TC:0    0x2ffcd8f8
E/TC:0    0x2ffcdf77
E/TC:0   Panic 'abort outside thread context' at core/arch/arm/kernel/abort.c:545 <abort_handler>
E/TC:0   TEE load address @ 0x2ffc0000
E/TC:0   Call stack:
E/TC:0    0x2ffc2499
E/TC:0    0x2ffcbb0b
E/TC:0    0x2ffc2101
E/TC:0    0x2ffc0b84

I’d like to ask if it’s actually possible to reduce the size of the reserved RAM for OP-TEE on this board, and if so, what would be the correct approach to do it?

[Olivier GALLIEN]

Hi @AVazquez ,

I wonder if this article How to configure a 256MB DDR mapping from STM32 MPU Distribution Package - stm32mpu may not help you in your investigation ? 

Olivier 

[AVazquez]

Thanks, @Olivier GALLIEN 

I wasn’t aware of that article before. I’ve just read through it.

It refers to reducing the overall DDR mapping from 512 MB to 256 MB, not shrinking the memory specifically reserved for OP‑TEE.

Cheers!