10d498393Swdenk 20d498393SwdenkCommands are added to U-Boot by creating a new command structure. 300309c67SPeter MeerwaldThis is done by first including command.h, then using the U_BOOT_CMD() macro 400309c67SPeter Meerwaldto fill in a cmd_tbl_t struct. 50d498393Swdenk 60d498393SwdenkU_BOOT_CMD(name,maxargs,repeatable,command,"usage","help") 70d498393Swdenk 80d498393Swdenkname: is the name of the commad. THIS IS NOT a string. 900309c67SPeter Meerwaldmaxargs: the maximum number of arguments this function takes 1000309c67SPeter Meerwaldrepeatable: either 0 or 1 to indicate if autorepeat is allowed 110d498393Swdenkcommand: Function pointer (*cmd)(struct cmd_tbl_s *, int, int, char *[]); 120d498393Swdenkusage: Short description. This is a string 1300309c67SPeter Meerwaldhelp: Long description. This is a string 140d498393Swdenk 150d498393Swdenk 1600309c67SPeter Meerwald**** Behind the scene ****** 170d498393Swdenk 18*ef123c52SAlbert ARIBAUDThe structure created is named with a special prefix and placed by 19*ef123c52SAlbert ARIBAUDthe linker in a special section using the linker lists mechanism 20*ef123c52SAlbert ARIBAUD(see include/linker_lists.h) 210d498393Swdenk 220d498393SwdenkThis makes it possible for the final link to extract all commands 230d498393Swdenkcompiled into any object code and construct a static array so the 24*ef123c52SAlbert ARIBAUDcommand array can be iterated over using the linker lists macros. 250d498393Swdenk 26*ef123c52SAlbert ARIBAUDThe linker lists feature ensures that the linker does not discard 27*ef123c52SAlbert ARIBAUDthese symbols when linking full U-Boot even though they are not 28*ef123c52SAlbert ARIBAUDreferenced in the source code as such. 292d1d6583STom Rini 300d498393SwdenkIf a new board is defined do not forget to define the command section 310d498393Swdenkby writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these 320d498393Swdenk3 lines: 330d498393Swdenk 346c7c946cSMarek Vasut .u_boot_list : { 35*ef123c52SAlbert ARIBAUD KEEP(*(SORT(.u_boot_list*))); 366c7c946cSMarek Vasut } 37