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Booting MPC8309twr custom board

Question asked by satish kumar Y on Oct 17, 2016
Latest reply on Oct 24, 2016 by satish kumar Y

I am trying to boot my MPC8309 custom board with NOR Flash with same memory map as referenced in MPC8309twr.


NOR Flash Memory MAP


The above memory map is given in the TWR-MPC8309_Linux_BSP_User_Manual.pdf.

so i have programmed u-boot.bin to its location 0xFE00_0000(NOR Flash base address) and later programmed the QE-ucode to its location 0xFE7E_0000.


what i was expected is u-boot has to be executed from its location 0xFE000000, but it doesn't boot.

so after again i studied the MPC8309RM.pdf(Refernce Manual) here i got doubt in BMS bit in RCWHR.


BMS defines the initial value of the e300 core MSR[IP] bit, which specifies the location of the interrupt
vectors (including the hard reset exception vector). The device defines the default boot ROM memory
space to be 8 Mbytes at addresses 0x0000_0000 to 0x007F_FFFF or 0xFF80_0000 to 0xFFFF_FFFF.
When the core comes out of reset, if it is enabled to boot, it fetches boot code from one of two addresses,
0x0000_0100 or 0xFFF0_0100, and exceptions are vectored to the physical addresses, 0x000n_nnnn or
0xFFFn_nnnn appropriately. This bit specifies whether an interrupt vector offset is prepended with 0xFFF
or 0x000. In the description below, n_nnnn is the offset of the exception vector.


Boot Memory Space bit in RCWHR


According to my preset values of CFG_RESET_SOURCE[0:3]=1000

RCWLR [0:31] = 0x42040003  & RCWHR [0:31] = 0xA460000

so i decoded this and i got '1' in BMS bit, according to BMS bit1 the boot code will be fetched from 0xFFF0_0100.

I again programmed the u-boot.bin at 0xFFF0_0000 location without erasing the previous programmed u-boot sectors(0xFE00_0000 - 0xFE09_FFFF) and my board gets up and i am able to load the kernel and mount my file system and it works fine(now uboot is at two locations in flash).

later i erased the previously programmed uboot sectors to confirm that the boot code is executed from 0xFFF0_0000 ad restarted the board, again the board stops booting. so i have loaded the u-boot.bin again to 0xFE00_0000 location then the board gets up. I dont understand that when boot code(u-boot) is present at two location then only board gets up otherwise it is not getting up and i have checked with md command in MPC8309twr reference board( here i have boot code in only at flash base address) but in my custom board the boot code is present at two locations(at flash base address & 0xFFF0_0000).

** i am justifying the board gets up by checking the uboot console prints.


If any one know the boot procedure that where the core fetches the boot code & where exactly the boot code has to be placed in Flash, please share me some information.



Satish Kumar