karo: tx6: prevent DTB from either being out of reach of kernel or overwritten during...

[karo-tx-uboot.git] / doc / README.commands

diff --git a/doc/README.commands b/doc/README.commands
index d678992d46fe51cebcb19041d031aaa6216e5eb1..afd5577b0a9ce66b86c52f7cae595eb7d914e556 100644 (file)
--- a/doc/README.commands
+++ b/doc/README.commands
@@ -1,31 +1,36 @@
 
 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.
+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
+maxargs: the maximum number of arguments this function takes
+repeatable: either 0 or 1 to indicate if autorepeat is allowed
 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
+help:   Long description. This is a string
 
 
-**** Behinde the scene ******
+**** Behind the scene ******
 
-The structure created is named with a special prefix (__u_boot_cmd_)
-and placed by the linker in a special section.
+The structure created is named with a special prefix and placed by
+the linker in a special section using the linker lists mechanism
+(see include/linker_lists.h)
 
 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.
+command array can be iterated over using the linker lists macros.
+
+The linker lists feature ensures that the linker does not discard
+these symbols when linking full U-Boot even though they are not
+referenced in the source code as such.
 
 If a new board is defined do not forget to define the command section
-by writing in u-boot.lds ($(TOPDIR)/board/boardname/u-boot.lds) these
+by writing in u-boot.lds ($(srctree)/board/boardname/u-boot.lds) these
 3 lines:
 
-       __u_boot_cmd_start = .;
-       .u_boot_cmd : { *(.u_boot_cmd) }
-       __u_boot_cmd_end = .;
+       .u_boot_list : {
+               KEEP(*(SORT(.u_boot_list*)));
+       }