[Buildroot] [PATCH] infra/pkg-kconfig: build host-ccache before kconfig

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Thu, 19 Jul 2018 09:47:09 +0000, ??? wrote:
> When the ccache is enabled, the HOSTCC variable refers to the ccache binary.
> 
> But the host-ccache is not a dependency of the kconfig's .config. Some targets
> such as `busybox-menuconfig` may calls Kconfig before the host-ccache is ready.
> If the host-ccache is not ready yet, the Kconfig will fail. Because it can not
> use $HOSTCC to build its utilities without ccache.
> 
> This issue can be reproduce with the following commands:
>  1. make clean defconfig
>  2. echo "BR2_CCACHE=y" >> .config
>  3. make olddefconfig busybox-menuconfig
> 
> This patch fixes this issue by add host-ccache to the dependencies of .config.
> So that the Kconfig can use $HOSTCC.
> 
> Signed-off-by: Zhai Zhaoxuan <zhaizhaoxuan@xiaomi.com>

Thanks for this contribution! However, I have not been able to
reproduce the problem with the steps you describe. Here is what happens
here:

thomas at windsurf:~/projets/buildroot (master)$ make clean defconfig
rm -rf /home/thomas/projets/buildroot/output/target /home/thomas/projets/buildroot/output/images /home/thomas/projets/buildroot/output/host  \
	/home/thomas/projets/buildroot/output/build /home/thomas/projets/buildroot/output/staging \
	/home/thomas/projets/buildroot/output/legal-info /home/thomas/projets/buildroot/output/graphs
mkdir -p /home/thomas/projets/buildroot/output/build/buildroot-config/lxdialog
PKG_CONFIG_PATH="" make CC="/usr/bin/gcc" HOSTCC="/usr/bin/gcc" \
    obj=/home/thomas/projets/buildroot/output/build/buildroot-config -C support/kconfig -f Makefile.br conf
/usr/bin/gcc -D_GNU_SOURCE -D_DEFAULT_SOURCE  -DCURSES_LOC="<ncurses.h>" -DNCURSES_WIDECHAR=1 -DLOCALE  -I/home/thomas/projets/buildroot/output/build/buildroot-config -DCONFIG_=\"\"  -MM *.c > /home/thomas/projets/buildroot/output/build/buildroot-config/.depend 2>/dev/null || :
/usr/bin/gcc -D_GNU_SOURCE -D_DEFAULT_SOURCE  -DCURSES_LOC="<ncurses.h>" -DNCURSES_WIDECHAR=1 -DLOCALE  -I/home/thomas/projets/buildroot/output/build/buildroot-config -DCONFIG_=\"\"   -c conf.c -o /home/thomas/projets/buildroot/output/build/buildroot-config/conf.o
/usr/bin/gcc -D_GNU_SOURCE -D_DEFAULT_SOURCE  -DCURSES_LOC="<ncurses.h>" -DNCURSES_WIDECHAR=1 -DLOCALE  -I/home/thomas/projets/buildroot/output/build/buildroot-config -DCONFIG_=\"\"  -I. -c /home/thomas/projets/buildroot/output/build/buildroot-config/zconf.tab.c -o /home/thomas/projets/buildroot/output/build/buildroot-config/zconf.tab.o
/usr/bin/gcc -D_GNU_SOURCE -D_DEFAULT_SOURCE  -DCURSES_LOC="<ncurses.h>" -DNCURSES_WIDECHAR=1 -DLOCALE  -I/home/thomas/projets/buildroot/output/build/buildroot-config -DCONFIG_=\"\"   /home/thomas/projets/buildroot/output/build/buildroot-config/conf.o /home/thomas/projets/buildroot/output/build/buildroot-config/zconf.tab.o  -o /home/thomas/projets/buildroot/output/build/buildroot-config/conf
rm /home/thomas/projets/buildroot/output/build/buildroot-config/zconf.tab.c
#
# configuration written to /home/thomas/projets/buildroot/.config
#
thomas at windsurf:~/projets/buildroot (master)$ echo "BR2_CCACHE=y" >> .config
thomas at windsurf:~/projets/buildroot (master)$ make olddefconfig busybox-menuconfig
/home/thomas/projets/buildroot/.config:3912:warning: override: reassigning to symbol BR2_CCACHE
#
# configuration written to /home/thomas/projets/buildroot/.config
#
make[1]: *** No rule to make target 'busybox-menuconfig'.  Stop.
make: *** [Makefile:79: _all] Error 2

I also tried manually a configuration with BR2_CCACHE enabled and
busybox enabled, and "make busybox-menuconfig" worked just fine,
without host-ccache being built.

> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 81bba5220c..44bcda4cd2 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -54,6 +54,10 @@ $(2)_KCONFIG_FIXUP_CMDS ?=
>  $(2)_KCONFIG_FRAGMENT_FILES ?=
>  $(2)_KCONFIG_DOTCONFIG ?= .config
>  
> +ifeq ($(BR2_CCACHE),y)
> +$(2)_KCONFIG_DEPENDENCIES += host-ccache
> +endif

I *think* what we will want instead is to use HOSTCC_NOCCACHE to build
the kconfig utilities.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com