Question about the size limit for loading data into SRAM during SD card booting of S32G399.

[seungtake]

I am operating by merging the final SD card image with the M7 .bin file generated from Design Studio, referencing the bsp44 m7-sample. (Currently, I am booting by reading the SD card from U-Boot and using the startm7 command.)

I would like to load both the TFA and the merged M7 .bin file into SRAM. Is it correct that I only need to modify the application size in the IVT table to achieve this? Additionally, I am curious whether the BootROM is initialized to allow access to the entire 20MB of SRAM without any size limitations, or if there are any restrictions.

[chenyin_h · Accepted solution]

Hello, @seungtake 

Thanks for you post.

1. When the TFA is built with m7 sample, the IVT is updated, and TFA part has been merged together with m7 sample, then the whole binary would be loaded to the sram once booted, including both M7 code and bl2 code, it is not necessary to modify IVT further.

2. I do not see restrictions from the RM, once tested on RDB3 loading RTD samples to different SRAM locations by the BootROM, no issues found, but in the application code(bootloader, M7 examples, etc.), it is needed to initialize the SRAM before using it. (via DCD or explicit code)

But for SD boot, there is following limitation:

As a result, the size for loading images during SD boot would be impact.

BR

Chenyin