| 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 = .; |