[J-u-boot.git] / doc / README.commands


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 = .;
Commit	Line	Data
0d498393 WD	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 = .;