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tn2916_boot_from_nand_omap2420.fm - Rev. D 6/07 EN
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TN-29-16: Boot-from-NAND with the TI OMAP2420 Processor
Boot-from-NAND Overview
Boot-from-NAND Overview
Figure 1 provides an overview of the boot sequence for an OMAP2420-based system
using boot-from-NAND.
Figure 1:
Boot-from-NAND Stages
Boot Stages
Stage 1: Processor ROM Code
During power-on, or after a RESET operation, the OMAP2420 processor runs its internal
ROM code. Note that only NAND Flash devices supported by the OMAP2420 processor
ROM can be used for the boot process (see Table 2 on page 4).
Stage 2: Bootstrap
X-Loader
is an example of stage 2 bootstrap code. The X-Loader code is stored in the
NAND Flash, and the ROM code copies it to the OMAP processor SRAM for execution.
Stage 3: Boot Loader
Stage 3 is the boot loader, which is used to copy the operating system code from the
NAND Flash to the DRAM; in this case U-Boot is the boot loader code. The U-Boot code
is stored in NAND Flash, and the stage 2 code copies it to the DRAM for execution.
Stage 4: Operating System
The OS code, such as the Linux kernel, is stored in the NAND Flash, and the stage 3 code
copies it to the DRAM, where it is executed. The boot process is complete after this stage
as the OS takes control of the system.
Stage 4
Operating System
Focus
of this
Technical
Note
Stage 3
Boot Loader
Stage 2
Boot-strap
Stage 1
Processor ROM Code
