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- Commands are added to U-Boot by creating a new command structure.
- This is done by first including command.h, then using the U_BOOT_CMD() macro
- to fill in a cmd_tbl_t struct.
- U_BOOT_CMD(name,maxargs,repeatable,command,"usage","help")
- name: is the name of the commad. THIS IS NOT a string.
- maxargs: the maximum number of arguments this function takes
- repeatable: either 0 or 1 to indicate if autorepeat is allowed
- command: Function pointer (*cmd)(struct cmd_tbl_s *, int, int, char *[]);
- usage: Short description. This is a string
- help: Long description. This is a string
- **** Behind the scene ******
- The structure created is named with a special prefix and placed by
- the linker in a special section using the linker lists mechanism
- (see include/linker_lists.h)
- This makes it possible for the final link to extract all commands
- compiled into any object code and construct a static array so the
- command array can be iterated over using the linker lists macros.
- The linker lists feature ensures that the linker does not discard
- these symbols when linking full U-Boot even though they are not
- referenced in the source code as such.
- If a new board is defined do not forget to define the command section
- by writing in u-boot.lds ($(srctree)/board/boardname/u-boot.lds) these
- 3 lines:
- .u_boot_list : {
- KEEP(*(SORT(.u_boot_list*)));
- }
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