Recently I have been studying the boot sequence for the 8540 based boards in U-Boot. I have a question on the location of the initial C stack.

As I understand it,

cpu/mpc85xx/start.S

uses L1 data cache as the location for the C stack prior to the relocation into RAM.

CFG_INIT_RAM_ADDR is defined within the relevant “config” file for each 6540 based board.

I see in the 8540 User Manual that there is a register which can be used to position L2 cache in physical address space but there does not appear to be a similar register for L1 cache.

However, I see that in the init.S files, for each board, entries are placed into TLB0 for memory at address CFG_INIT_RAM_ADDR. This is declared as cacheable and non-garded.

Am I correct in thinking that this is all that is required to position the C run-time stack in L1 D-cache ?

Thanks,

Charles.

--------------------------------------------------------------------------  Dr Charles J Gillan The Institute of Electronics, Communications and Information Technology (ECIT),                Queen's University Belfast, Titanic Quarter Queen’s Road, Queen’s Island, Belfast, BT3 9DT Northern Ireland, UK   Tel: +44 (0) 2890 971847 Fax: +44 (0) 2890 971702    ---------------------------------------------------------------------------