The on-chip BOOTROM first sets up the L2 cache and the SPI controller. It then reads CSIB_NBL1FW and CLIB_NBL1FW configuration data to get the position of the bootstage in flash. It then loads 192KiB from flash into L2 cache to a fixed address. The boot mode is called “Non-Secure-Boot” as the signature of the bootstage isn’t verified. The BOOTROM can do AES decryption for obfuscation or verify the signature of the bootstage. Both features aren’t used and won’t be described any further.
- The typical position of bootstage in flash is at address 0x20000.
- The entry point in physical DRAM is at address 0x100000.
Bootflow of Cavium CN8xxx SoCs