RE: [U-Boot-Users] Generic ARM Error with respect to usage of r8 in start.S's.
What is it you don't see? Why we reserve R8 for global data?
The u-boot for ARM code defines and uses global data which is not referenced using r8 (can be seen by all). The code as currently generated only uses r8 to access into the bd_info structure and its members. As it is, the bd_info structure is allocated on the C stack in start_armboot(), there is nothing special about the sdram which its allocated in. The structure could have as easily been defined as a global above, just like flash_info[] or any other structure is. There is no selective relocation...it don't really use C code features until it has a stack.
Yes the flexibility to do different things is there which is good, unfortunately the leaving of expansion hooks which break the existing code somewhat defeats its usefulness.
Regards,
Richard W.
In message FD2AC9A020DDD51194710008C7089B20053D4CAD@dlee17.itg.ti.com you wrote:
The u-boot for ARM code defines and uses global data which is not referenced using r8 (can be seen by all). The code as currently generated only uses r8 to access into the bd_info structure and its members. As it is, the bd_info
No. All access to the "global data pointer" ("*gd") goes through r8, as defined in "include/asm-arm/global_data.h":
#define DECLARE_GLOBAL_DATA_PTR register gd_t *gd asm ("r8")
structure is allocated on the C stack in start_armboot(), there is nothing special about the sdram which its allocated in. The structure could have as
As mentioned before, the ARM initialization sequence and memory map do not exactly fit into the U-Boot model as it was intended to be. The curerent state is a result of the port done for the ARMBoot project, but this is a temporary state which will be fixed in a future release.
Yes the flexibility to do different things is there which is good, unfortunately the leaving of expansion hooks which break the existing code somewhat defeats its usefulness.
The problem is that we obviously missed the exception code when chosing r8. If you can, please submit a patch to fix this problem.
Best regards,
Wolfgang Denk
participants (2)
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Wolfgang Denk -
Woodruff, Richard