From: Tom Rini Date: Thu, 20 Sep 2012 06:02:43 +0000 (+0000) Subject: README.commands: Document what UNDEF_SYM does X-Git-Tag: v2012.10-rc2~45 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=2d1d65838eacd314b989701bd2f9e2b657bbf62b;p=kernel%2Fu-boot.git README.commands: Document what UNDEF_SYM does Changes in v2: - Reword a bit more Signed-off-by: Tom Rini --- diff --git a/doc/README.commands b/doc/README.commands index 27815d2..125f077 100644 --- a/doc/README.commands +++ b/doc/README.commands @@ -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: