Dear Albert ARIBAUD,
In message 4CE0221A.7030502@free.fr you wrote:
Alright, then I think we should document how we comply, or do not comply, with GNU EABI / AAPCS (maybe a README.arm that people could read up) -- and I think if there is a way to access GD both before and after relocation without making a register unavailable to the whole u-boot code, then we should use it.
By the way - it should be not difficult to use a normal extern pointer to reference the global data; see "arch/powerpc/include/asm/global_data.h":
194 #if 1 195 #define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r2") 196 #else /* We could use plain global data, but the resulting code is bigger */ 197 #define XTRN_DECLARE_GLOBAL_DATA_PTR extern 198 #define DECLARE_GLOBAL_DATA_PTR XTRN_DECLARE_GLOBAL_DATA_PTR \ 199 gd_t *gd 200 #endif
When I implemented this code I tested both versions. There is not much of a difference, except that the register based version results in smaller code.
Best regards,
Wolfgang Denk