The best way is do the checksum. Copy 1MB from Flash to RAM_G and get the CRC32. repeat this depending on the size of the flash memory you use. This will ensure you have correct flash images every time you boot.
ex: I only use 3MB of external flash to store all the assets I need. Everytime I boot up, I only do the CRC of first 3MB. Ignore the rest. This should be quick.
ex: I only use 3MB of external flash to store all the assets I need. Everytime I boot up, I only do the CRC of first 3MB. Ignore the rest. This should be quick.