STM32MP157D-DK1 missing RAM

[MHerz.1]

Hello, I'm currently working with a STM32MP157D-DK1 Development Board with 4GB DDR3L. I populated the board with a prebuild openstlinux 6.1 build like discribed in a guide in the ST wiki.

When checking the total memory i unfortunatly only get 407MB that are used.

root@stm32mp1:~# free --mega
               total        used        free      shared  buff/cache   available
Mem:             407         138         152          13         140         269
Swap:              0           0           0

 Is there a way to use the complete 4GB of RAM?

Kind regards,

Markus

[PatrickF · Accepted solution]

HI @MHerz.1 , 407MBytes sound normal. The memory is 4Gbits which is 512MBytes and some part are probably reserved for OpTee, DMA buffers and exchange buffers with Cortex-M4.

Regards

[PatrickF]

Few more details in dmesg

root@stm32mp1:~# dmesg | grep Memory:
[    0.000000] Memory: 325492K/524288K available (12288K kernel code, 1371K rwdata, 3636K rodata, 1024K init, 235K bss, 133260K reserved, 65536K cma-reserved, 0K highmem)

Maybe look into this page (not fully related, but some interesting information about DDR mapping)
https://wiki.st.com/stm32mpu/wiki/How_to_configure_a_256MB_DDR_mapping_from_STM32_MPU_Distribution_Package#Introduction

Regards.