Re: [PATCH 21/23] kbuild: use absolute path in the generated wrapper Makefile

[Caleb Connolly <caleb.connolly@linaro.org>]

Hi Masahiro,

On 9/17/24 16:16, Masahiro Yamada wrote:
> Keep the consistent behavior when this Makefile is invoked from another
> directory.

This breaks building in a chroot for me. I usually compile the kernel on 
my host and then use some tooling to just run the "package" step of an 
Alpine kernel package definition. See

https://wiki.postmarketos.org/wiki/Compiling_kernels_with_envkernel.sh#Packaging_kernels_built_without_envkernel

Since this requires mounting the source directory into a chroot, and 
then symlinking the output directory to the package "src" dir. It relies 
on the fact that make can be run from the output directory and 
implicitly relies on the include being relative since the absolute paths 
don't map inside the chroot.

I'm not sure if breakages like this justify a revert, but I noticed this 
issue in -next the other day and thought it was at least worth reporting.

I wouldn't be surprised if other folks with other build systems get 
bitten by this too.

Kind regards,
Caleb
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>   Makefile | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index ce646a6994a6..9f0ba07e8f25 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -643,8 +643,9 @@ ifdef building_out_of_srctree
>   
>   quiet_cmd_makefile = GEN     Makefile
>         cmd_makefile = { \
> -	echo "\# Automatically generated by $(srctree)/Makefile: don't edit"; \
> -	echo "include $(srctree)/Makefile"; \
> +	echo "\# Automatically generated by $(abs_srctree)/Makefile: don't edit"; \
> +	echo "export KBUILD_OUTPUT = $(CURDIR)"; \
> +	echo "include $(abs_srctree)/Makefile"; \
>   	} > Makefile
>   
>   outputmakefile: