Richard Danter wrote:
Richard Danter wrote:
Hi all,
Further progress on my port. I can now write to flash!
I noticed in lib_ppc/board.c board_init_r() that on e500 CPU's the unlock_ram_in_cache() function is called. The 7xx/74xx also locks the init RAM in the dcache, but nowhere is it unlocked.
I tried calling unlock_ram_in_cache() from my board's misc_init_r() function, but this crashes U-Boot.
As an experiment, I left the cache locked, but then ran the "dcache off" command from the shell. If I do printenv before turning the dcache off it is all OK, if I do it after then it crashes.
With my debugger I can see that the gd data structure is garbage when env_get_char_memory() is called. But I thought all data was copied to the main sys RAM.
Is there something else I need to do before/after calling unlock_ram_in_cache() so I can use the D-Cache as normal?
Since I now have system RAM initialised very early on, I tried using the system RAM instead of the dcache for init RAM. That works fine. I do not now need to call unlock_ram_in_cache() and I can turn the dcache off/on without breaking printenv.
Just to check things out,I used "mw" to write a pattern over where the init RAM is placed. After that, printenv fails again. So it seems something is wrong within the relocation of global variables.
I have not changed the code to do the relocation, so am I just misunderstanding what it does? Is there some #define I may have forgotten?
By default, the gd_t pointer (gd) remains pointing to init RAM, not to the relocated RAM on 7xx/74xx. I had to explicitly set gd to point to the relocated version in my after_reloc() function and ensure the correct value is passed to after_reloc() by start.S (relocate_code).
Seems odd this is not the default.
Rich