Alex Zeffertt writes:
Alex> Hi list, I would like to boot my MPC8272ADS board from the Alex> base of flash memory. By default the BCSR delivers a fixed Alex> HRCW which tells the CPU to boot from 0xff700000.
No, it tells CPU to boot from 0xfff00000. There are only two possible start addresses: 0x100 and 0xfff00100.
Alex> But there is a jumper on the board which allows you to specify Alex> that the CPU should retrieve the HRCW from flash.
Alex> In an attempt to get it to boot from 0x0 I tried the Alex> following:
Alex> 1. Moved jumper JP9 from "BCSR" to "MEMORY" to tell the CPU to Alex> get its HRCW from flash rather than the BCSR.
Correct. Also make sure it boots from flash and not from EEPROM (SW2 #1).
Alex> 2. Set TEXT_BASE in config.mk to 0x0
This is wrong. You have to set TEXT_BASE to the address at which you will burn the U-Boot image to flash. If you're going to burn U-Boot to the first flash sector, TEXT_BASE must be equal to CFG_FLASH_BASE.
Alex> 3. define CFG_HRCW_MASTER in MPC8260ADS.h to be the value Alex> normally delivered by the BCSR or'd with (HRCW_CIP | Alex> HRCW_BMS). This should move the reset vector from Alex> 0xfff00100 to 0x100
Correct.
Alex> and cause the flash to be mapped from Alex> 0x0 to 0x01ffffff.
Initially mapped. It's remapped to CFG_BR0_PRELIM by the U-Boot's code. This is the reason why TEXT_BASE=0 can't work.
Alex> Unfortunately this didn't work.
Alex> Has anybody else managed to get the MPC8272ADS to boot WITHOUT Alex> using the BCSR to deliver the HRCW?