X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;f=doc%2FREADME.commands;h=125f077c08ffc03f7cf549e6c54480e3a6a41b87;hb=833b6435de3e8cf5b06ba81cb1b2b50e044269ff;hp=d678992d46fe51cebcb19041d031aaa6216e5eb1;hpb=0d4983930a3559be92452761cfa268ee9d0f2773;p=u-boot

diff --git a/doc/README.commands b/doc/README.commands
index d678992d46..125f077c08 100644
--- a/doc/README.commands
+++ b/doc/README.commands
@@ -1,19 +1,19 @@
 
 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.
@@ -22,6 +22,13 @@ 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.
 
+To ensure that the linker does not discard these symbols when linking
+full U-Boot we generate a list of all the commands we have built (based
+on the sections mentioned above) and use that to force the linker to
+first enter the symbol as undefined in the output object so that there
+is then a need for the symbol to be kept (this is the UNDEF_SYM logic in
+the Makefile).
+
 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: