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README.commands

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  • Forked from Reform / reform-boundary-uboot
    36641 commits behind the upstream repository.
    README.commands 1.07 KiB
    
    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 maximumn numbers of arguments this function takes
    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
    
    
    **** Behinde the scene ******
    
    The structure created is named with a special prefix (__u_boot_cmd_)
    and placed by the linker in a special section.
    
    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 can be found in an array starting at __u_boot_cmd_start.
    
    If a new board is defined do not forget to define the command section
    by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these
    3 lines:
    
    	__u_boot_cmd_start = .;
    	.u_boot_cmd : { *(.u_boot_cmd) }
    	__u_boot_cmd_end = .;