RM0082
BootROM
Doc ID 018672 Rev 1
831/844
Figure 114. Boot flows
38.5.1
Serial NOR Flash boot
In NOR Boot, BootROM tries to perform BootROM bypass i.e. BootROM tries to
authenticate U-boot in the first sector of Flash, if U-boot is found then BootROM jumps to the
U-boot (ih_load location plus 0x40), otherwise if U-boot authentication fails then BootROM
tries to authenticate X-Loader, if X-loader is found, then BootROM copies X-Loader from
Flash to 'shadow memory' area and jumps to X-Loader in 'shadow memory'. The load
address of X-Loader is also specified in 64 bytes X-Loader header (ih_load).
If X-Loader authentication fails, or any other error is occurs during serial NOR boot,
BootROM shifts to USB boot.
Start
Initialize interrupts
SMI initialization
BootROM
bypass?
Jump to load address
Test boot type
Yes
Booting
Success?
Proceed to specific
boot
No
Infinite loop
Jump to X - loader/ U - Boot
Yes
No