3.1 Boot Process Stages

The following figure illustrates the boot process flow.

Figure 3-1. ROM Code Flow Diagram

The stages of the boot process are:

  1. Setting up the chip
    • Out of reset, the ROM code is running and this cannot be bypassed in any way.
    • The ROM code keeps JTAG disabled and enables it back just before exiting.
    • The ROM code configures a clock scheme.
    • The ROM code configures a console based on the instance selected in the boot configuration packet.
  2. Searching for a valid bootstrap in the non-volatile memories (NVMs) listed in the boot sequence
    • The ROM code searches for a valid bootstrap in all NVMs listed in the boot sequence from the boot configuration packet, in the exact order they are listed.
    • The ROM code boots the first NVM device with a valid bootstrap. For further details on the boot sequence, check the device data sheet (see Reference Documents).