QSPI issue

I am using STM32F746 controller and MX25L128 flash on a custom board.

I want to make external flash loader file for my custom board.

I followed the MOOC - External QSPI loader how to

I got error while memcmp

 for (var = 0; var < SECTORS_COUNT; var++) {
 if (memcmp(buffer_test,
 (uint8_t*) (0x90000000 + var * MEMORY_SECTOR_SIZE),
 MEMORY_SECTOR_SIZE) != HAL_OK) {
 while (1)
 ; //breakpoint - error detected - otherwise QSPI works properly
 }
 }