From: Masahiro Yamada <masahiroy@kernel.org>
To: linux-kbuild@vger.kernel.org
Cc: Randy Dunlap <rdunlap@infradead.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Michal Marek <michal.lkml@markovi.net>,
linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 7/7] kbuild: doc: document subdir-y syntax
Date: Sat, 28 Nov 2020 20:51:08 +0900 [thread overview]
Message-ID: <20201128115108.179256-7-masahiroy@kernel.org> (raw)
In-Reply-To: <20201128115108.179256-1-masahiroy@kernel.org>
There is no explanation about subdir-y.
Let's document it.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
---
(no changes since v1)
Documentation/kbuild/makefiles.rst | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index 4fd6b327a19f..a276bfa93675 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/Documentation/kbuild/makefiles.rst
@@ -319,6 +319,21 @@ more details, with real examples.
that directory specifies obj-y, those objects will be left orphan.
It is very likely a bug of the Makefile or of dependencies in Kconfig.
+ Kbuild also supports dedicated syntax, subdir-y and subdir-m, for
+ descending into subdirectories. It is a good fit when you know they
+ do not contain kernel-space objects at all. A typical usage is to let
+ Kbuild descend into subdirectories to build tools.
+
+ Examples::
+
+ # scripts/Makefile
+ subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
+ subdir-$(CONFIG_MODVERSIONS) += genksyms
+ subdir-$(CONFIG_SECURITY_SELINUX) += selinux
+
+ Unlike obj-y/m, subdir-y/m does not need the trailing slash since this
+ syntax is always used for directories.
+
It is good practice to use a `CONFIG_` variable when assigning directory
names. This allows kbuild to totally skip the directory if the
corresponding `CONFIG_` option is neither 'y' nor 'm'.
--
2.27.0
next prev parent reply other threads:[~2020-11-28 22:17 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-28 11:51 [PATCH v2 1/7] kbuild: doc: update the description about kbuild Makefiles Masahiro Yamada
2020-11-28 11:51 ` [PATCH v2 2/7] kbuild: doc: replace arch/$(ARCH)/ with arch/$(SRCARCH)/ Masahiro Yamada
2020-11-28 11:51 ` [PATCH v2 3/7] kbuild: doc: fix 'List directories to visit when descending' section Masahiro Yamada
2020-11-28 11:51 ` [PATCH v2 4/7] kbuild: doc: merge 'Special Rules' and 'Custom kbuild commands' sections Masahiro Yamada
2020-11-28 11:51 ` [PATCH v2 5/7] kbuild: doc: split if_changed explanation to a separate section Masahiro Yamada
2020-11-28 11:51 ` [PATCH v2 6/7] kbuild: doc: clarify the difference between extra-y and always-y Masahiro Yamada
2020-11-28 11:51 ` Masahiro Yamada [this message]
2020-12-01 10:43 ` [PATCH v2 1/7] kbuild: doc: update the description about kbuild Makefiles Masahiro Yamada
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201128115108.179256-7-masahiroy@kernel.org \
--to=masahiroy@kernel.org \
--cc=corbet@lwn.net \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michal.lkml@markovi.net \
--cc=rdunlap@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).