X-Git-Url: https://git.sur5r.net/?a=blobdiff_plain;ds=inline;f=doc%2FREADME.commands;h=9eb367104fd9a1bc77ede04bc11c1ead51b602b9;hb=2dd285f571c5880314903a0a19b8b7da0175661c;hp=923418b1a455a4dc610c4efd4c5f59b5d5da6263;hpb=c7656bab411433f987baa2288eff8c78ddc0f378;p=u-boot diff --git a/doc/README.commands b/doc/README.commands index 923418b1a4..9eb367104f 100644 --- a/doc/README.commands +++ b/doc/README.commands @@ -15,24 +15,22 @@ help: Long description. This is a string **** Behind the scene ****** -The structure created is named with a special prefix (__u_boot_list_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_list_cmd__start. +command array can be iterated over using the linker lists macros. -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). +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 3 lines: .u_boot_list : { - #include "u-boot.lst"; + KEEP(*(SORT(.u_boot_list*))); }