kconfig: store default ARCH in .config

Cross-compiler tool prefix can be set in command line, in the environment variable CROSS_COMPILE or in config file, in option CONFIG_COROSS_COMPILE. Also some arch/*/Makefile provides default value.

This patch links config option CONFIG_CROSS_COMPILE and variable CROSS_COMPILE in both directions: environment/command line has higher priority and updates value saved in the config file, config option acts as default value for it.

This is especially useful together with option O=dir which allows to create separate directory for each target architecture and kernel flavor:

# make O=build/arm ARCH=arm CROSS_COMPILE=arm-none-eabi- defconfig
# make -C build/arm

Signed-off-by Konstantin Khlebnikov <[email protected]>

---
 Makefile     |    6 +++++-
 init/Kconfig |    1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

Makefile +5 -1

index f648405..1044f40 100644
@@ -263,7 +263,11 @@ endif
 # "make" in the configured kernel build directory always uses that.
 # Default value for CROSS_COMPILE is not to prefix executables
 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
-CROSS_COMPILE	?= $(CONFIG_CROSS_COMPILE:"%"=%)
+ifndef CROSS_COMPILE
+	CROSS_COMPILE := $(shell $(srctree)/scripts/config \
+				--file $(KBUILD_OUTPUT)$(KCONFIG_CONFIG) \
+				--if-undef "" --state "CROSS_COMPILE")
+endif
 
 # Architecture as present in compile.h
 UTS_MACHINE 	:= $(ARCH)

init/Kconfig +0 -0

index e84c642..1c2f621 100644

Hi Konstantin,

Quoted 8 lines · Konstantin Khlebnikov

Cross-compiler tool prefix can be set in command line, in the environment variable CROSS_COMPILE or in config file, in option CONFIG_COROSS_COMPILE. Also some arch/*/Makefile provides default value.

This patch links config option CONFIG_CROSS_COMPILE and variable CROSS_COMPILE in both directions: environment/command line has higher priority and updates value saved in the config file, config option acts as default value for it.

Quoted 7 lines

This is especially useful together with option O=dir which allows to create separate directory for each target architecture and kernel flavor:

# make O=build/arm ARCH=arm CROSS_COMPILE=arm-none-eabi- defconfig
# make -C build/arm

Signed-off-by Konstantin Khlebnikov <[email protected]>

I have only had a quick glance at this series. Just a quick question to help me understand where it is going.

Would this patch mean that, if a (def)config file has both ARCH and CROSS_COMPILE set, one could use that (def)config file and invoke "make $whatever_target" and expect it to do the right thing (provided a suitable cross compiler is installed)?

This implies cross compiler prefixes are standardized across distributions, I guess. Maybe they're not.

Quoted 29 lines

---
 Makefile     |    6 +++++-
 init/Kconfig |    1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

Makefile +5 -1

index f648405..1044f40 100644
@@ -263,7 +263,11 @@ endif
 # "make" in the configured kernel build directory always uses that.
 # Default value for CROSS_COMPILE is not to prefix executables
 # Note: Some architectures assign CROSS_COMPILE in their arch/*/Makefile
-CROSS_COMPILE        ?= $(CONFIG_CROSS_COMPILE:"%"=%)
+ifndef CROSS_COMPILE
+     CROSS_COMPILE := $(shell $(srctree)/scripts/config \
+                             --file $(KBUILD_OUTPUT)$(KCONFIG_CONFIG) \
+                             --if-undef "" --state "CROSS_COMPILE")
+endif
 
 # Architecture as present in compile.h
 UTS_MACHINE  := $(ARCH)

init/Kconfig +0 -0

index e84c642..1c2f621 100644

init/Kconfig config INIT_ENV_ARG_LIMIT · line 53

Quoted 7 lines

init/Kconfig +1 -0

@@ -47,6 +47,7 @@ config INIT_ENV_ARG_LIMIT
 
 config CROSS_COMPILE
      string "Cross-compiler tool prefix"
+     option env="CROSS_COMPILE"
      help
        Same as running 'make CROSS_COMPILE=prefix-' but stored for
        default make runs in this kernel build directory.  You don't

Paul Bolle

This is second attempt of fixing target archecture amnesia. v1 patch: http://lkml.kernel.org/r/20140706080234.19520.96704.stgit@zurg

First version saved ARCH as CONFIG_DEFAULT_ARCH and used it as defult ARCH.

This version changes semantic of Kconfig option env="...", now it acts more like the user input, except that the value comes from the environment. Variable from environment overrides all defaults and value from config file. If environment variable is not defined this option has no effect.

So, now ARCH is saved as CONFIG_ARCH.

Also this patchset links CONFIG_CROSS_COMPILE and CROSS_COMPILE in the same way. Changing it in command line/environment also updates value in the config file.

Hi Konstantin,

Quoted 12 lines · Konstantin Khlebnikov

This is second attempt of fixing target archecture amnesia. v1 patch: http://lkml.kernel.org/r/20140706080234.19520.96704.stgit@zurg

First version saved ARCH as CONFIG_DEFAULT_ARCH and used it as defult ARCH.

This version changes semantic of Kconfig option env="...", now it acts more like the user input, except that the value comes from the environment. Variable from environment overrides all defaults and value from config file. If environment variable is not defined this option has no effect.

So, now ARCH is saved as CONFIG_ARCH.

Quoted 2 lines

Also this patchset links CONFIG_CROSS_COMPILE and CROSS_COMPILE in the same way. Changing it in command line/environment also updates value in the config file.

Thanks, I haven't tried this yet, but it looks promising!

For the record, right now I use a GNUmakefile (which takes precedence over the Makefile) in the build directory containing e.g.

MAKEARGS = ARCH=arm CROSS_COMPILE=arm-unknown-linux-gnueabi-

MAKEFLAGS += --no-print-directory

.PHONY: all $(MAKECMDGOALS)

all := $(filter-out all Makefile,$(MAKECMDGOALS))

all:

        $(MAKE) $(MAKEARGS) $(all) -f Makefile

Makefile:;

$(all) %/: all

        @:

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds

This is second attempt of fixing target archecture amnesia. v1 patch: http://lkml.kernel.org/r/20140706080234.19520.96704.stgit@zurg

First version saved ARCH as CONFIG_DEFAULT_ARCH and used it as defult ARCH.

This version changes semantic of Kconfig option env="...", now it acts more like the user input, except that the value comes from the environment. Variable from environment overrides all defaults and value from config file. If environment variable is not defined this option has no effect.

So, now ARCH is saved as CONFIG_ARCH.

Also this patchset links CONFIG_CROSS_COMPILE and CROSS_COMPILE in the same way. Changing it in command line/environment also updates value in the config file.

---

Konstantin Khlebnikov (4):
kconfig: save values imported from environment into config file scripts/config: add option for changing output for undefined options
kconfig: get target architecture from config file
kconfig: link CONFIG_CROSS_COMPILE with environment variable

 Documentation/kbuild/kconfig-language.txt |   10 ++++------
 Documentation/kbuild/makefiles.txt        |    3 ++-
 Makefile                                  |   21 +++++++++++++++------
 init/Kconfig                              |    1 +
 scripts/config                            |   15 ++++++++++++---
 scripts/kconfig/confdata.c                |   26 ++++++++++++++++++++++++++
 scripts/kconfig/expr.h                    |    2 +-
 scripts/kconfig/symbol.c                  |    3 ---
 8 files changed, 61 insertions(+), 20 deletions(-)

--
Signature

Bump.

Quoted 33 lines · Konstantin Khlebnikov

This is second attempt of fixing target archecture amnesia. v1 patch: http://lkml.kernel.org/r/20140706080234.19520.96704.stgit@zurg

First version saved ARCH as CONFIG_DEFAULT_ARCH and used it as defult ARCH.

This version changes semantic of Kconfig option env="...", now it acts more like the user input, except that the value comes from the environment. Variable from environment overrides all defaults and value from config file. If environment variable is not defined this option has no effect.

So, now ARCH is saved as CONFIG_ARCH.

Also this patchset links CONFIG_CROSS_COMPILE and CROSS_COMPILE in the same way. Changing it in command line/environment also updates value in the config file.

---

Konstantin Khlebnikov (4):
kconfig: save values imported from environment into config file scripts/config: add option for changing output for undefined options
kconfig: get target architecture from config file
kconfig: link CONFIG_CROSS_COMPILE with environment variable

 Documentation/kbuild/kconfig-language.txt |   10 ++++------
 Documentation/kbuild/makefiles.txt        |    3 ++-
 Makefile                                  |   21 +++++++++++++++------
 init/Kconfig                              |    1 +
 scripts/config                            |   15 ++++++++++++---
 scripts/kconfig/confdata.c                |   26 ++++++++++++++++++++++++++
 scripts/kconfig/expr.h                    |    2 +-
 scripts/kconfig/symbol.c                  |    3 ---
 8 files changed, 61 insertions(+), 20 deletions(-)