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Re: [PATCH v2] Kbuild: tiny correction on `make help`

Started byCao jin <caoj.fnst@cn.fujitsu.com>
First post2017-06-13 12:00 +0200
Last post2017-06-14 09:40 +0200
Articles 4 — 3 participants

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  Re: [PATCH v2] Kbuild: tiny correction on `make help` Cao jin <caoj.fnst@cn.fujitsu.com> - 2017-06-13 12:00 +0200
    Re: [PATCH v2] Kbuild: tiny correction on `make help` Masahiro Yamada <yamada.masahiro@socionext.com> - 2017-06-14 03:20 +0200
      Re: [PATCH v2] Kbuild: tiny correction on `make help` Cao jin <caoj.fnst@cn.fujitsu.com> - 2017-06-14 09:10 +0200
        Re: [PATCH v2] Kbuild: tiny correction on `make help` Michal Marek <mmarek@suse.com> - 2017-06-14 09:40 +0200

#1664667 — Re: [PATCH v2] Kbuild: tiny correction on `make help`

FromCao jin <caoj.fnst@cn.fujitsu.com>
Date2017-06-13 12:00 +0200
SubjectRe: [PATCH v2] Kbuild: tiny correction on `make help`
Message-ID<tRQMb-6li-29@gated-at.bofh.it>
Yamada-san,

  I have a question on the current top level Makefile. There are
following lines, I have trouble to understand "firstword x$(MAKEFLAGS)"
in 2nd line, why there is a 'x' there?


  ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
  ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
    quiet=silent_
    tools_silent=s
  endif
  else                                    # make-3.8x
  ifneq ($(filter s% -s%,$(MAKEFLAGS)),)
    quiet=silent_
    tools_silent=-s
  endif
  endif

  I already read & understand your patch[*] and know these lines will be
modified, but I have spent quite a few days on understanding it, so I
still want to know the purpose of 'x'.

[*]https://lkml.org/lkml/2017/5/19/371

-- 
Sincerely,
Cao jin

On 06/06/2017 11:01 PM, Masahiro Yamada wrote:
> 2017-06-06 18:07 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
>> The help info of `make C=1` is little confusing, make it clear.
>>
>> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> 
> 
> Applied to linux-kbuild/fixes.  Thanks!
> 

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#1665349

FromMasahiro Yamada <yamada.masahiro@socionext.com>
Date2017-06-14 03:20 +0200
Message-ID<tS58u-6WS-13@gated-at.bofh.it>
In reply to#1664667
2017-06-13 18:52 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
> Yamada-san,
>
>   I have a question on the current top level Makefile. There are
> following lines, I have trouble to understand "firstword x$(MAKEFLAGS)"
> in 2nd line, why there is a 'x' there?
>
>
>   ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
>   ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)


I do not understand the 'x' either.

Michal suggested the code according to the following:
https://patchwork.kernel.org/patch/3291301/
(I hope Michal can help you.)


My first guess was, it was added just in case $(MAKEFLAGS) is empty.
Actually $(firstword ) seems to work with empty argument, though.



-- 
Best Regards
Masahiro Yamada

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#1665494

FromCao jin <caoj.fnst@cn.fujitsu.com>
Date2017-06-14 09:10 +0200
Message-ID<tSaBb-25w-7@gated-at.bofh.it>
In reply to#1665349

On 06/14/2017 09:15 AM, Masahiro Yamada wrote:
> 2017-06-13 18:52 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
>> Yamada-san,
>>
>>   I have a question on the current top level Makefile. There are
>> following lines, I have trouble to understand "firstword x$(MAKEFLAGS)"
>> in 2nd line, why there is a 'x' there?
>>
>>
>>   ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
>>   ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
> 
> 
> I do not understand the 'x' either.
> 
> Michal suggested the code according to the following:
> https://patchwork.kernel.org/patch/3291301/
> (I hope Michal can help you.)
> 

It does helps.

> 
> My first guess was, it was added just in case $(MAKEFLAGS) is empty.
> Actually $(firstword ) seems to work with empty argument, though.
> 

I see, I guess you are saying it was added in case there is no
single-letter flags in $(MAKEFLAGS) while it has "--debug=jobs", that
make sense to me. Thanks very much, Yamada-san.

-- 
Sincerely,
Cao jin

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#1665515

FromMichal Marek <mmarek@suse.com>
Date2017-06-14 09:40 +0200
Message-ID<tSb4e-2hd-11@gated-at.bofh.it>
In reply to#1665494
Dne 14.6.2017 v 09:08 Cao jin napsal(a):
> 
> 
> On 06/14/2017 09:15 AM, Masahiro Yamada wrote:
>> 2017-06-13 18:52 GMT+09:00 Cao jin <caoj.fnst@cn.fujitsu.com>:
>>> Yamada-san,
>>>
>>>   I have a question on the current top level Makefile. There are
>>> following lines, I have trouble to understand "firstword x$(MAKEFLAGS)"
>>> in 2nd line, why there is a 'x' there?
>>>
>>>
>>>   ifneq ($(filter 4.%,$(MAKE_VERSION)),)  # make-4
>>>   ifneq ($(filter %s ,$(firstword x$(MAKEFLAGS))),)
>>
>>
>> I do not understand the 'x' either.
>>
>> Michal suggested the code according to the following:
>> https://patchwork.kernel.org/patch/3291301/
>> (I hope Michal can help you.)
>>
> 
> It does helps.
> 
>>
>> My first guess was, it was added just in case $(MAKEFLAGS) is empty.
>> Actually $(firstword ) seems to work with empty argument, though.
>>
> 
> I see, I guess you are saying it was added in case there is no
> single-letter flags in $(MAKEFLAGS) while it has "--debug=jobs", that
> make sense to me. Thanks very much, Yamada-san.

Well, it more than three years ago. But yes, I believe that was the
intention:

make --foo=s

x$(MAKEFLAGS) => x --foo=s
$(firstword x$(MAKEFLAGS)) => x

Michal

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