Re: [for-4.19][PATCH] build: Allow setting KBUILD_DEFCONFIG in the environment

[Jan Beulich <jbeulich@xxxxxxxx>]

On 25.10.2023 10:28, Michal Orzel wrote:
> At the moment, in order to use a different defconfig target than default,
> one needs to specify KBUILD_DEFCONFIG=<target> on the command line.
> Switch to weak assignment, so that it can be also obtained from
> environment similar to other KCONFIG/KBUILD variables.
> 
> This change will activate the use of KBUILD_DEFCONFIG variable in CI
> build jobs that so far had no effect.

I'm certainly okay with the change, but the above sentence looks misleading
to me: Yes, the envvar was ignored so far, but isn't it the case that the
envvar as specified in CI matches what Makefile set it to (taking into
account that for RISC-V riscv64_defconfig aliases tiny64_defconfig), and
hence the specifications in build.yaml could be dropped (until such time
where truly an override was intended)?

Jan

> Note, that we will deviate from Linux in this regard.
> 
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> ---
> In case of reluctance to this approach, we can always do:
>  make -C xen defconfig KBUILD_DEFCONFIG=${KBUILD_DEFCONFIG}
> in automation/scripts/build.
> 
> Also, Linux defers setting the variable to arch specific Makefile, so it is 
> not
> sth mandated by the top level Makefile or documentation.
> ---
>  xen/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/Makefile b/xen/Makefile
> index fd0e63d29efb..40feefff4ab5 100644
> --- a/xen/Makefile
> +++ b/xen/Makefile
> @@ -256,7 +256,8 @@ export YACC = $(if $(BISON),$(BISON),bison)
>  export LEX = $(if $(FLEX),$(FLEX),flex)
>  
>  # Default file for 'make defconfig'.
> -export KBUILD_DEFCONFIG := $(ARCH)_defconfig
> +# May be overruled on the command line or set in the environment.
> +export KBUILD_DEFCONFIG ?= $(ARCH)_defconfig
>  
>  # Copy CFLAGS generated by "Config.mk" so they can be reused later without
>  # reparsing Config.mk by e.g. arch/x86/boot/.