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References: <20190130111447.26032-1-vladimir.kondratiev@linux.intel.com>
In-Reply-To: <20190130111447.26032-1-vladimir.kondratiev@linux.intel.com>
From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Fri, 1 Feb 2019 13:18:15 +0900
Message-ID: <CAK7LNAS8g3g3OTtqTN8begMxzbSS82Wn0CqY8u6vuELEZaLo3g@mail.gmail.com>
Subject: Re: [PATCH] kbuild: gitignore output directory
To:     Vladimir Kondratiev <vladimir.kondratiev@linux.intel.com>
Cc:     Michal Marek <michal.lkml@markovi.net>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Jan 30, 2019 at 8:15 PM Vladimir Kondratiev
<vladimir.kondratiev@linux.intel.com> wrote:
>
> When compiling into output directory using O=, many files
> created under KBUILD_OUTPUT that git considers
> as new ones; git clients, ex. "git gui" lists it, and it clutters
> file list making it difficult to see what was really changed
>
> Generate .gitignore in output directory that ignores all
> its content
>
> Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@linux.intel.com>
> ---
>  Makefile | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 141653226f3c..ee66ea28869b 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -483,10 +483,13 @@ PHONY += outputmakefile
>  # outputmakefile generates a Makefile in the output directory, if using a
>  # separate output directory. This allows convenient use of make in the
>  # output directory.
> +# At the same time when output Makefile generated, generate .gitignore to
> +# ignore whole output directory
>  outputmakefile:
>  ifneq ($(KBUILD_SRC),)
>         $(Q)ln -fsn $(srctree) source
>         $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
> +       echo "# this is build directory, ignore it\n*" > .gitignore
>  endif
>
>  ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)
> --
> 2.19.1
>


The idea looks OK to me.
The implementation must be improved.


You need to add $(Q) to suppress the annoying command echo.

Also, this patch does not work for all distributions because
echo "\n"
is not portable.


GNU Make runs recipes in /bin/sh (unless SHELL variable is changed),
but the implementation of /bin/sh depends on distributions.


This patch works on Ubuntu etc.
because /bin/sh is a symbolic link to dash.


But, in some distributions,
/bin/sh is a symbolic link to bash.


Docker is useful for quick tests of
various distributions. :)

See the result of  echo "hello\nworld"


[Ubuntu]

foo@8ad1275125c5:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.10
DISTRIB_CODENAME=cosmic
DISTRIB_DESCRIPTION="Ubuntu 18.10"
foo@8ad1275125c5:~$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 Nov 14 23:00 /bin/sh -> dash
foo@8ad1275125c5:~$ /bin/sh
$ type echo
echo is a shell builtin
$ echo "hello\nworld"
hello
world


[CentOS]


[foo@c3fbaa4b6f72 ~]$ cat /etc/redhat-release
CentOS Linux release 7.6.1810 (Core)
[foo@c3fbaa4b6f72 ~]$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 Dec  5 01:36 /bin/sh -> bash
[foo@c3fbaa4b6f72 ~]$ /bin/sh
sh-4.2$ type echo
echo is a shell builtin
sh-4.2$ echo "hello\nworld"
hello\nworld


On example for workaround might be:

diff --git a/Makefile b/Makefile
index ee66ea2..010c1c6 100644
--- a/Makefile
+++ b/Makefile
@@ -489,7 +489,7 @@ outputmakefile:
 ifneq ($(KBUILD_SRC),)
        $(Q)ln -fsn $(srctree) source
        $(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkmakefile $(srctree)
-       echo "# this is build directory, ignore it\n*" > .gitignore
+       $(Q){ echo "# this is build directory, ignore it"; echo "*"; }
> .gitignore
 endif

 ifneq ($(shell $(CC) --version 2>&1 | head -n 1 | grep clang),)


-- 
Best Regards
Masahiro Yamada