[U-Boot] Problem with u-boot after stage 0

[Mirko Banchi]

Hi all, we have developed a board very similar to MPC8306SOM board. We have some problems to run u-boot on. Briefly, the board has the same main components of the som board (RAM, NAND chip and a MPC8306 microprocessor) so we tried to use the same u-boot-nand.bin image for the boot. Something happens: the board starts, prints the message "NAND boot...transfering control" and nothing else happens. The first code is executed in NAND until nand_boot function (defined in the file nand_spl/nand_boot_fsl_elbc.c) is called: this copies in RAM the u-boot image and jumps at the address 0x01000000. To make we sure that RAM is working ok we have modified the u-boot-nand.bin with istructions that reset the processor and all works ok. Surely the jump at 0x01000000 happens and u-boot code starts to be executed but surely for some unknown reasons something goes wrong. Follow the u-boot code is very difficult also because is not clear to us how the "parts" of the boot loader are linked togheter. Now some questions:

1- Looking at the dump of u-boot-nand.bin we saw that there are two "parts" of code very similar: one starts at offset 0x0 and the other at offset 0x20000. Both parts begin with a reset configuration word followed by the u-boot magic number, string version etc... Which is the purpose of this two parts?This could be useful to better understand the boot process. For now we know only that the processor reads the configuration word in NAND at offset 0x0 and starts to execute istructions from offset 0x100 in NAND. The second "part" (that starts at offset 0x20000) is then copied in RAM and the code that is executed is at location 0x01000120 in RAM.

2 - In the function nand_boot defined in nand_spl/nand_boot_fsl_elbc.c the last istruction is the call to the function pointed by the function pointer uboot (its value is 0x01000120). Where can i find the code executed here? Which is the relative source file? Looking at that source file maybe i can find where the boot could stop.  

Thank you all very much!

Best regards,

Mirko

--
Mirko Banchi

e-mail:    mk.banchi at gmail.com
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