Re: [PATCH 2/3] selftests/gpio: fix build error

[Fathi Boudra]

On 23 June 2017 at 13:37, Marcin Nowakowski
<marcin.nowakowski@xxxxxxxxxx> wrote:
> While building selftests/gpio, gpio-utils from linux/tools/gpio as built
> in the process as well. However, the OUTPUT make variable usage in
> selftests breaks the build system in linux/tools/gpio resulting in its
> output files placed in the selftests folder (due to lack of trailing
> slash in the path, the files are placed directly in selftests):
>
> make -f linux/tools/build/Makefile.build dir=. obj=lsgpio
> make[3]: Entering directory '/mnt/ssd/MIPS/linux-next/tools/gpio'
> CC    linux/tools/testing/selftests/gpiolsgpio.o
> CC    linux/tools/testing/selftests/gpiogpio-utils.o
> LD    linux/tools/testing/selftests/gpiolsgpio-in.o
>
> This pollutes the selftests directory and, most importantly, makes it
> impossible for selftests/gpio to find the object file it's looking for
> to link the test:
>
> cc -O2 -g -std=gnu99 -Wall -I../../../../usr/include/
> gpio-mockup-chardev.c ../../../gpio/gpio-utils.o
> ../../../../usr/include/linux/gpio.h  -lmount -I/usr/include/libmount -o
> gpio-mockup-chardev
> gcc: error: ../../../gpio/gpio-utils.o: No such file or directory
>
> Fix this by clearing the OUTPUT variable when invoking linux/tools/gpio
> make to ensure it's built where expected.
>
> Note, that this solution is not ideal as the output is placed in
> linux/tools/gpio rather than a location relative to OUTPUT, but this at
> least ensures the build succeeds.
> Due to differences and complexities of selftests and linux/tools build
> systems, it's not trivial to ensure linux/tools get built properly when
> invoked recursively from selftests build and this is left as a future
> task to resolve properly.
>
> Fixes: a8ba798bc8ec ('selftests: enable O and KBUILD_OUTPUT')
>
> Signed-off-by: Marcin Nowakowski <marcin.nowakowski@xxxxxxxxxx>

FWIW, I've tested the patch and it fixes the issue mentioned.

Tested-by: Fathi Boudra <fathi.boudra@xxxxxxxxxx>

> ---
>  tools/testing/selftests/gpio/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
> index 298929d..950956e 100644
> --- a/tools/testing/selftests/gpio/Makefile
> +++ b/tools/testing/selftests/gpio/Makefile
> @@ -23,7 +23,7 @@ LDLIBS += -lmount -I/usr/include/libmount
>  $(BINARIES): ../../../gpio/gpio-utils.o ../../../../usr/include/linux/gpio.h
>
>  ../../../gpio/gpio-utils.o:
> -       make ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) -C ../../../gpio
> +       make ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE) -C ../../../gpio OUTPUT=
>
>  ../../../../usr/include/linux/gpio.h:
>         make -C ../../../.. headers_install INSTALL_HDR_PATH=$(shell pwd)/../../../../usr/
> --
> 2.7.4
>
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