wdenk | f287a24 | 2003-07-01 21:06:45 +0000 | [diff] [blame^] | 1 | |
| 2 | Commands are added to U-Boot by creating a new command structure. |
| 3 | This is done by first including command.h |
| 4 | |
| 5 | Then using the U_BOOT_CMD() macro to fill in a cmd_tbl_t struct. |
| 6 | |
| 7 | U_BOOT_CMD(name,maxargs,repeatable,command,"usage","help") |
| 8 | |
| 9 | name: is the name of the commad. THIS IS NOT a string. |
| 10 | maxargs: the maximumn numbers of arguments this function takes |
| 11 | command: Function pointer (*cmd)(struct cmd_tbl_s *, int, int, char *[]); |
| 12 | usage: Short description. This is a string |
| 13 | help: long description. This is a string |
| 14 | |
| 15 | |
| 16 | **** Behinde the scene ****** |
| 17 | |
| 18 | The structure created is named with a special prefix (__u_boot_cmd_) |
| 19 | and placed by the linker in a special section. |
| 20 | |
| 21 | This makes it possible for the final link to extract all commands |
| 22 | compiled into any object code and construct a static array so the |
| 23 | command can be found in an array starting at __u_boot_cmd_start. |
| 24 | |
| 25 | If a new board is defined do not forget to define the command section |
| 26 | by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these |
| 27 | 3 lines: |
| 28 | |
| 29 | __u_boot_cmd_start = .; |
| 30 | .u_boot_cmd : { *(.u_boot_cmd) } |
| 31 | __u_boot_cmd_end = .; |