Re: [PATCH v2 05/11] kbuild: change working directory to external module directory with M=

[Thorsten Blum <thorsten.blum@linux.dev>]

On 10. Nov 2024, at 02:34, Masahiro Yamada wrote:
> 
> Currently, Kbuild always operates in the output directory of the kernel,
> even when building external modules. This increases the risk of external
> module Makefiles attempting to write to the kernel directory.
> 
> This commit switches the working directory to the external module
> directory, allowing the removal of the $(KBUILD_EXTMOD)/ prefix from
> some build artifacts.
> 
> The command for building external modules maintains backward
> compatibility, but Makefiles that rely on working in the kernel
> directory may break. In such cases, $(objtree) and $(srctree) should
> be used to refer to the output and source directories of the kernel.
> 
> The appearance of the build log will change as follows:
> 
> [Before]
> 
>  $ make -C /path/to/my/linux M=/path/to/my/externel/module
>  make: Entering directory '/path/to/my/linux'
>    CC [M]  /path/to/my/externel/module/helloworld.o
>    MODPOST /path/to/my/externel/module/Module.symvers
>    CC [M]  /path/to/my/externel/module/helloworld.mod.o
>    CC [M]  /path/to/my/externel/module/.module-common.o
>    LD [M]  /path/to/my/externel/module/helloworld.ko
>  make: Leaving directory '/path/to/my/linux'
> 
> [After]
> 
>  $ make -C /path/to/my/linux M=/path/to/my/externel/module
>  make: Entering directory '/path/to/my/linux'
>  make[1]: Entering directory '/path/to/my/externel/module'
>    CC [M]  helloworld.o
>    MODPOST Module.symvers
>    CC [M]  helloworld.mod.o
>    CC [M]  .module-common.o
>    LD [M]  helloworld.ko
>  make[1]: Leaving directory '/path/to/my/externel/module'
>  make: Leaving directory '/path/to/my/linux'
> 
> Printing "Entering directory" twice is cumbersome. This will be
> addressed later.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---

Hi Masahiro,

I get the following error since this patch is in master, but only when
using COCCI= in combination with M=<relative or absolute path>.

It works when I either use COCCI= or M=, but not with both.

$ make coccicheck COCCI=scripts/coccinelle/misc/flexible_array.cocci M=arch/
make[1]: Entering directory '/home/fedora/linux/arch'
You have not explicitly specified the mode to use. Using default "report" mode.
Available modes are the following: patch, report, context, org, chain
You can specify the mode with "make coccicheck MODE=<mode>"
Note however that some modes are not implemented by some semantic patches.

Please check for false positives in the output before submitting a patch.
When using "patch" mode, carefully review the patch before submitting it.

grep: scripts/coccinelle/misc/flexible_array.cocci: No such file or directory
grep: scripts/coccinelle/misc/flexible_array.cocci: No such file or directory
/usr/bin/spatch -D report --no-show-diff --very-quiet --cocci-file scripts/coccinelle/misc/flexible_array.cocci --patch /home/fedora/linux --dir . -I /home/fedora/linux/arch/arm64/include -I /home/fedora/linux/arch/arm64/include/generated -I /home/fedora/linux/include -I /home/fedora/linux/include -I /home/fedora/linux/arch/arm64/include/uapi -I /home/fedora/linux/arch/arm64/include/generated/uapi -I /home/fedora/linux/include/uapi -I /home/fedora/linux/include/generated/uapi --include /home/fedora/linux/include/linux/compiler-version.h --include /home/fedora/linux/include/linux/kconfig.h --jobs 4 --chunksize 1
Fatal error: exception Sys_error("scripts/coccinelle/misc/flexible_array.cocci: No such file or directory")
coccicheck failed
make[2]: *** [/home/fedora/linux/Makefile:2089: coccicheck] Error 2
make[1]: *** [/home/fedora/linux/Makefile:251: __sub-make] Error 2
make[1]: Leaving directory '/home/fedora/linux/arch'
make: *** [Makefile:251: __sub-make] Error 2

Thanks,
Thorsten