Commit eb38f37c authored Oct 13, 2020 by Lukas Bulwahn Committed by Linus Torvalds Oct 13, 2020

kbuild: doc: describe proper script invocation



During an investigation to fix up the execute bits of scripts in the
kernel repository, Andrew Morton and Kees Cook pointed out that the
execute bit should not matter, and that build scripts cannot rely on that.
Kees could not point to any documentation, though.

Masahiro Yamada explained the convention of setting execute bits to make
it easier for manual script invocation.

Provide some basic documentation how the build shall invoke scripts, such
that the execute bits do not matter, and acknowledge that execute bits are
useful nonetheless.

This serves as reference for further clean-up patches in the future.

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ujjwal Kumar <ujjwalkumar0501@gmail.com>
Cc: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/lkml/20200830174409.c24c3f67addcce0cea9a9d4c@linux-foundation.org/
Link: https://lore.kernel.org/lkml/202008271102.FEB906C88@keescook/
Link: https://lore.kernel.org/linux-kbuild/CAK7LNAQdrvMkDA6ApDJCGr+5db8SiPo=G+p8EiOvnnGvEN80gA@mail.gmail.com/
Link: https://lkml.kernel.org/r/20201001075723.24246-1-lukas.bulwahn@gmail.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 4d6fb34a

Documentation/kbuild/makefiles.rst

+20 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@ This document describes the Linux kernel Makefiles.
		--- 3.10 Special Rules
		--- 3.11 $(CC) support functions
		--- 3.12 $(LD) support functions
		--- 3.13 Script Invocation

		=== 4 Host Program support
		--- 4.1 Simple Host Program
		@@ -605,6 +606,25 @@ more details, with real examples.
		#Makefile
		LDFLAGS_vmlinux += $(call ld-option, -X)

		3.13 Script invocation
		----------------------

		Make rules may invoke scripts to build the kernel. The rules shall
		always provide the appropriate interpreter to execute the script. They
		shall not rely on the execute bits being set, and shall not invoke the
		script directly. For the convenience of manual script invocation, such
		as invoking ./scripts/checkpatch.pl, it is recommended to set execute
		bits on the scripts nonetheless.

		Kbuild provides variables $(CONFIG_SHELL), $(AWK), $(PERL),
		$(PYTHON) and $(PYTHON3) to refer to interpreters for the respective
		scripts.

		Example::

		#Makefile
		cmd_depmod = $(CONFIG_SHELL) $(srctree)/scripts/depmod.sh $(DEPMOD) \
		$(KERNELRELEASE)

		4 Host Program support
		======================

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