Re: [PATCH 2/2] kbuild: rename built-in.o to built-in.a

From: Masahiro Yamada <yamada.masahiro@socionext.com>
To: Nicholas Piggin <npiggin@gmail.com>
Cc: Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Michal Marek <michal.lkml@markovi.net>
Subject: Re: [PATCH 2/2] kbuild: rename built-in.o to built-in.a
Date: Mon, 12 Feb 2018 09:57:32 +0900	[thread overview]
Message-ID: <CAK7LNAQwrtJyydyvvjjtOngCkc9WLk9-0Pk57GpfCP9srAQQrg@mail.gmail.com> (raw)
In-Reply-To: <20180211211508.4261ebf2@roar.ozlabs.ibm.com>

2018-02-11 20:15 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
> On Sun, 11 Feb 2018 13:38:04 +0900
> Masahiro Yamada <yamada.masahiro@socionext.com> wrote:
>
>> 2018-02-10 23:25 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>:
>> > Incremental linking is gone, so rename built-in.o to built-in.a, which
>> > is the usual extension for archive files.
>> >
>> > This patch does two things, first is a simple search/replace:
>> >
>> > git grep -l 'built-in\.o' | xargs sed -i 's/built-in\.o/built-in\.a/g'
>> >
>> > The second is to invert nesting of nested text manipulations to avoid
>> > filtering built-in.a out from libs-y2:
>> >
>> > -libs-y2 := $(filter-out %.a, $(patsubst %/, %/built-in.a, $(libs-y)))
>> > +libs-y2 := $(patsubst %/, %/built-in.a, $(filter-out %.a, $(libs-y)))
>> >
>> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
>>
>>
>> I think this is the right thing to do, but I have no idea
>> why 'less kernel/built-in.a' shows strange output.
>> Do you have a clue?
>>
>>
>> Without this patch,
>> 'emacs kernel/built-in.o'
>> 'cat kernel/built-in.o'
>> 'less kernel/built-in.o'
>>
>> showed me the same content.
>>
>> $ less kernel/built-in.o | head -n 10
>> !<thin>
>> //                                              2964      `
>> fork.o/
>> exec_domain.o/
>> panic.o/
>> cpu.o/
>> exit.o/
>> softirq.o/
>> resource.o/
>> sysctl.o/
>>
>>
>>
>>
>> After applying this patch,
>> 'less kernel/built-in.a' is strange.
>>
>>
>> $ less kernel/built-in.a | head -n 10
>> rw-r--r-- 0/0  60216 Jan  1 09:00 1970 kernel/fork.o
>> rw-r--r-- 0/0   3648 Jan  1 09:00 1970 kernel/exec_domain.o
>> rw-r--r-- 0/0  20552 Jan  1 09:00 1970 kernel/panic.o
>> rw-r--r-- 0/0  87752 Jan  1 09:00 1970 kernel/cpu.o
>> rw-r--r-- 0/0  34136 Jan  1 09:00 1970 kernel/exit.o
>> rw-r--r-- 0/0  41448 Jan  1 09:00 1970 kernel/softirq.o
>> rw-r--r-- 0/0  40904 Jan  1 09:00 1970 kernel/resource.o
>> rw-r--r-- 0/0  60968 Jan  1 09:00 1970 kernel/sysctl.o
>> rw-r--r-- 0/0   4472 Jan  1 09:00 1970 kernel/sysctl_binary.o
>> rw-r--r-- 0/0  12472 Jan  1 09:00 1970 kernel/capability.o
>>
>>
>> However, 'cat kernel/built-in.a' works as I expect.
>>
>> $ cat  kernel/built-in.a | head -n 10
>> !<thin>
>> //                                              2964      `
>> fork.o/
>> exec_domain.o/
>> panic.o/
>> cpu.o/
>> exit.o/
>> softirq.o/
>> resource.o/
>> sysctl.o/
>>
>>
>>
>> Is my 'less' insane?
>> Or, is this intentional behavior of 'less'?
>
> Interesting, my less does not do that. Instead of the raw contents
> of the file, yours is providing output of `ar tv`, which is
> reconstructing more of the archive metadata. I guess it is keyed
> on the filename extension.

Ah, I see.  'ar tv' and 'less' gave me the same output.

> Do you have an alias for it, or maybe the distro patches the tool?

I use Ubuntu 16.04 LTS.

Not alias'ed

$ type less
less is hashed (/usr/bin/less)
$ /usr/bin/less kernel/built-in.a | head -n 10
rw-r--r-- 0/0  60216 Jan  1 09:00 1970 kernel/fork.o
rw-r--r-- 0/0   3648 Jan  1 09:00 1970 kernel/exec_domain.o
rw-r--r-- 0/0  20552 Jan  1 09:00 1970 kernel/panic.o
rw-r--r-- 0/0  87752 Jan  1 09:00 1970 kernel/cpu.o
rw-r--r-- 0/0  34136 Jan  1 09:00 1970 kernel/exit.o
rw-r--r-- 0/0  41448 Jan  1 09:00 1970 kernel/softirq.o
rw-r--r-- 0/0  40904 Jan  1 09:00 1970 kernel/resource.o
rw-r--r-- 0/0  60968 Jan  1 09:00 1970 kernel/sysctl.o
rw-r--r-- 0/0   4472 Jan  1 09:00 1970 kernel/sysctl_binary.o
rw-r--r-- 0/0  12472 Jan  1 09:00 1970 kernel/capability.o

Could be patched by the disto.

> It seems a bit rude for your less tool to reformat data for you.
>
> Thanks,
> Nick
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-- 
Best Regards
Masahiro Yamada