From mboxrd@z Thu Jan  1 00:00:00 1970
From: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>
Date: Thu, 25 Dec 2008 01:55:05 +0900
Subject: [U-Boot] [RFC][PATCH] Code Clean-up (weak functions)
In-Reply-To: <005501c965d1$a95ceee0$fc16cca0$@Tjernlund@transmode.se>
References: <1229145986-9936-1-git-send-email-graeme.russ@gmail.com>	<49518CF0.2040903@necel.com>
	<005501c965d1$a95ceee0$fc16cca0$@Tjernlund@transmode.se>
Message-ID: <49526969.5000402@ruby.dti.ne.jp>
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Joakim Tjernlund wrote:
>>> - There is no purely weak functions and therfore no longer code like:
>>>     if (do_something)
>>>       do_somthing();
>>>   All instances have been replaced by empty functions with an alias. e.g.
>>>      void __do_something (args) {}
>>>      do_something(args) __atttribute__((weak, alias("__do_something")));
> 
> Curious as to why you removed such code? Was it because it didn't work? If
> so I might have an answer for that. See my post:
> "Re: [U-Boot] [PATCH V4] cmd_bdinfo: move implementation to	arch	instead of common"
> 
>  Jocke

Good to know.  This doc also helps:

http://docs.sun.com/app/docs/doc/817-1984/chapter2-11?l=en&a=view

Then,
- we must try to not leave undefined weak symbols at all,
- or check the symbol before invocation for the safety in case of NULL
  dereference.