U-Boot powerpc MPC8309 TEXT_BASE

[ganjiaravind]

Hi, everyone here i have a question in u-boot source code ,when u-boot.bin is loaded from NOR Flash we consider the TEXT_BASE value as 0XFFF0_0000 in case of (RCWHR[BMS] is 1) and this address will match with the flash device address over Local Bus ,But when u-boot.bin need to get from an SD-card or a SPI EEPROM device what will be the TEXT_BASE and how we relate that value to the address over booting device (SD/MMC,SPI) ,can anyone here to help me in understanding

                       thanks in advance.

[alexander_yakov]

Booting from SPI or SD-card is performed with using onchip ROM, in this case the core starts from this onchip ROM, performs some initialization (SPI or SD-card driver bring up), and then loads firmware from specially formatted SPI or SD-card, and than run it. Because of this reason, special "ramboot" version of U-boot should be used. For more detailed description please please look application note AN3659. This document is not directly applicable to MPC8309, but can be used for better understanding

https://www.nxp.com/docs/en/application-note/AN3659.pdf 

Regarding your question about TEXT_BASE - for MPC8309 this parameter should be 0x01000000

Have a great day,
Alexander
TIC

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