linux-kernel - Re: Regression in "kbuild: fix if_change and friends to consider argument order"

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Message-ID: <CAK7LNAS4228scb3Ep1MT_FZhHS_+ckJCJZSDT-TN9hcvJ7Wq0A@mail.gmail.com>
Date:	Tue, 7 Jun 2016 20:29:57 +0900
From:	Masahiro Yamada <yamada.masahiro@...ionext.com>
To:	Michal Marek <mmarek@...e.cz>
Cc:	"Zanoni, Paulo R" <paulo.r.zanoni@...el.com>,
	"linux-kbuild@...r.kernel.org" <linux-kbuild@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"nicolas.pitre@...aro.org" <nicolas.pitre@...aro.org>
Subject: Re: Regression in "kbuild: fix if_change and friends to consider
 argument order"

2016-06-07 19:48 GMT+09:00 Michal Marek <mmarek@...e.cz>:
> On 2016-06-07 12:03, Masahiro Yamada wrote:
>> 2016-06-07 18:58 GMT+09:00 Michal Marek <mmarek@...e.cz>:
>>> On 2016-06-07 11:38, Michal Marek wrote:
>>>> On 2016-06-07 03:38, Zanoni, Paulo R wrote:
>>>>> Hi
>>>>>
>>>>> I recently noticed that alternating between "make" and "make targz-pkg"
>>>>> rebuilds the whole Kernel. This was not happening before. As a Kernel
>>>>> developer, my build/install/test environment heavily relies on the fact
>>>>> that "make targz-pkg" only quickly generates the tarball if everything
>>>>> is already built, so this change is heavily impacting my development
>>>>> environment.
>>>>>
>>>>> I did some bisection and concluded that the first bad commit is:
>>>>>
>>>>> commit 9c8fa9bc08f60ac657751daba9fccf828a36cfed
>>>>> Author: Masahiro Yamada
>>>>> Date:   Sat May 7 15:48:26 2016 +0900
>>>>>     kbuild: fix if_change and friends to consider argument order
>>>>>
>>>>> I also verified that if I just revert this commit on top of the
>>>>> most recent tree it goes back to the usual behavior.
>>>>>
>>>>> I read the commit message and it seems that some unneeded rebuilds are
>>>>> somewhat expected, but I can't understand why such a change in the
>>>>> command line like the one I did triggers everything to be rebuilt.
>>>>> IMHO, it really shouldn't. I also wonder that maybe the regression I'm
>>>>> experiencing was not expected in the original change, so maybe there's
>>>>> a way to keep the original improvement caused by the mentioned patch
>>>>> without the regression I'm experiencing.
>>>>>
>>>>> How to reproduce (exact commands I used at every bisect step):
>>>>>
>>>>> $ make tinyconfig
>>>>> $ time make -j4 V=2 # this should build things
>>>>> $ time make -j4 V=2 # just to make sure nothing will be rebuilt
>>>>> $ time make -j4 V=2 targz-pkg
>>>>
>>>> I can reproduce it.
>>>
>>> Try the attached patch.
>>>
>>> Michal
>>>
>>
>>
>> Right.
>>
>> I had already sent a similar patch.
>> https://patchwork.kernel.org/patch/9159863/
>
> I see. I hadn't read all my mail before replying.
>
>
>> My concern is it is effectively
>> reverting e8f5bdb02ce0.
>> I hope Rik can comment on that.
>
> My patch just resets NOSTDINC_FLAGS before including the arch Makefile.
>

Ah, I missed that, sorry.

Then, yours should be no problem.



-- 
Best Regards
Masahiro Yamada