linux-kernel - Re: special handle of scripts/kconfig/zconf.tab.o

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Date:   Mon, 21 Aug 2017 11:36:34 +0800
From:   Cao jin <caoj.fnst@...fujitsu.com>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Sam Ravnborg <sam@...nborg.org>
CC:     Michal Marek <mmarek@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Subject: Re: special handle of scripts/kconfig/zconf.tab.o

Hi,
  Thank you both for those valuable info.

On 08/19/2017 08:42 PM, Masahiro Yamada wrote:
> Hi.
> (+CC Sam)
> 
> 2017-08-15 20:02 GMT+09:00 Cao jin <caoj.fnst@...fujitsu.com>:
>> Masahiro-san,
>>
>> I have a question about make *config. In scripts/kconfig/Makefile, there
>> is following statement:
>>
>> $(obj)/zconf.tab.o: $(obj)/zconf.lex.c $(obj)/zconf.hash.c
>>
>> and the $(obj)/zconf.{tab,hash,lex}.c match the rule in Makefile.lib:
>>
>> $(obj)/%: $(src)/%_shipped
>>         $(call cmd,shipped)
>>
>> and cmd_shipped just transform the _shipped file to .c via `cat`.
>>
>> And zconf.tab.c includes several *other* .c files which make the whole
>> process a little obscure, because there are not corresponding .o files
>> for the *other* .c files.
>>
>> My questions is: Does this special handling has other meanings that I
>> may miss? Or just legacy.
> 

> 
> 
>> Because a straightforward way in my mind would be:
>>
>> rename zconf.{tab,hash,lex}.c_shipped to zconf.{tab,hash,lex}.c, then
>> has following in the Makefile
>>
>> common-objs := zconf.tab.o zconf.hash.o zconf.lex.o util.o etc...
>> conf-objs := conf.o $(common-objs)
>>
> 

> 
> 
> Here, we have one more question.
> 
> 
> Can we generate zconf.{tab,hash,lex}.c from zconf.{y,gperf,l}
> instead of from *_shipped?
> 
> This is also possible, technically.
> But, I do not know if it is acceptable to have
> more external tool dependencies.
> (So, I sent RFC patches to hear more opinions.)
> 

I think this is good for the new comers who don't know those tools
before. When I come to here. I just noticed that kbuild will cat
*_shipped file to the corresponding .c file, and miss the part that the
.c file is actually created by the tools.

And another new-comer friendly improvement may be something like: remove
"include *.c" lines in zconf.y, and modify makefile like I said above.
 So I will not get confused when I see symbols within certain .c file is
used while don't see the certain .o file.

-- 
Sincerely,
Cao jin