Hi @Reyna_pan45,
Have a look at the default linker_flash_s32k312.ld and startup_cm7.s, the SRAM ECC is initialized up to __INT_SRAM_END which is ORIGIN(ram_rsvd2). You placed the new section behind that, so it is not initialized.

Before the memory can be read, its ECC must be initialized.
It can be initialized later, but it must be a 64bit write.

The SRAM is retain through functional system reset only.
The bootloader / application can check the source of the reset and skip the ECC initialization if needed, this was discussed here: https://community.nxp.com/t5/S32K/SRAM-ECC-Initialization-for-S32K344/m-p/1764143
There can be also issues with the MPU that is initialized in system.c
This would result in a MemManage fault exception.
Regards,
Daniel