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Commit eed9382d authored by Masahiro Yamada's avatar Masahiro Yamada Committed by Mars Lin
Browse files

UPSTREAM: kbuild: ensure full rebuild when the compiler is updated 



Commit 21c54b77 ("kconfig: show compiler version text in the top
comment") added the environment variable, CC_VERSION_TEXT in the comment
of the top Kconfig file. It can detect the compiler update, and invoke
the syncconfig because all environment variables referenced in Kconfig
files are recorded in include/config/auto.conf.cmd

This commit makes it a CONFIG option in order to ensure the full rebuild
when the compiler is updated.

This works like follows:

include/config/kconfig.h contains "CONFIG_CC_VERSION_TEXT" in the comment
block.

The top Makefile specifies "-include $(srctree)/include/linux/kconfig.h"
to guarantee it is included from all kernel source files.

fixdep parses every source file and all headers included from it,
searching for words prefixed with "CONFIG_". Then, fixdep finds
CONFIG_CC_VERSION_TEXT in include/config/kconfig.h and adds
include/config/cc/version/text.h into every .*.cmd file.

When the compiler is updated, syncconfig is invoked because init/Kconfig
contains the reference to the environment variable CC_VERTION_TEXT.
CONFIG_CC_VERSION_TEXT is updated to the new version string, and
include/config/cc/version/text.h is touched.

In the next rebuild, Make will rebuild every files since the timestamp
of include/config/cc/version/text.h is newer than that of target.

Bug: 168274246

Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
(cherry picked from commit 8b59cd81dc5e724eaea283fa6006985891c7bff4)
Signed-off-by: default avatarMars Lin <marslin@google.com>
Change-Id: Ie52bb8e33b95d0e97998024d28c0d8d7caf8aa59
parent 3a95b905

Kconfig

+0 −2
Original line number Diff line number Diff line
@@ -5,8 +5,6 @@ 
#

mainmenu "Linux/$(ARCH) $(KERNELVERSION) Kernel Configuration"



comment "Compiler: $(CC_VERSION_TEXT)"



source "scripts/Kconfig.include"



source "init/Kconfig"

include/linux/kconfig.h

+2 −0
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#ifndef __LINUX_KCONFIG_H

#define __LINUX_KCONFIG_H



/* CONFIG_CC_VERSION_TEXT (Do not delete this comment. See help in Kconfig) */



#include <generated/autoconf.h>



#ifdef CONFIG_CPU_BIG_ENDIAN

init/Kconfig

+17 −0
Original line number Diff line number Diff line
@@ -9,6 +9,23 @@ config DEFCONFIG_LIST 
	default ARCH_DEFCONFIG

	default "arch/$(ARCH)/defconfig"



config CC_VERSION_TEXT

	string

	default "$(CC_VERSION_TEXT)"

	help

	  This is used in unclear ways:



	  - Re-run Kconfig when the compiler is updated

	    The 'default' property references the environment variable,

	    CC_VERSION_TEXT so it is recorded in include/config/auto.conf.cmd.

	    When the compiler is updated, Kconfig will be invoked.



	  - Ensure full rebuild when the compier is updated

	    include/linux/kconfig.h contains this option in the comment line so

	    fixdep adds include/config/cc/version/text.h into the auto-generated

	    dependency. When the compiler is updated, syncconfig will touch it

	    and then every file will be rebuilt.



config CC_IS_GCC

	def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)