Re: [PATCH] kbuild: gitignore output directory

From: Masahiro Yamada
Date: Thu Jan 31 2019 - 23:19:25 EST


On Wed, Jan 30, 2019 at 8:15 PM Vladimir Kondratiev
<vladimir.kondratiev@xxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxx>
> ---
> 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