Re: [kvm-unit-tests PATCH v2] Makefile: Use CFLAGS in cc-option

[Alexandru Elisei <alexandru.elisei@arm.com>]

Hi Drew,

Thank you for debugging this. I tested the patch by compiling the MTE test
from Vladimir with clang and it works now:

Tested-by: Alexandru Elisei <alexandru.elisei@arm.com>

Thanks,
Alex

On Fri, Mar 07, 2025 at 10:18:29AM +0100, Andrew Jones wrote:
> When cross compiling with clang we need to specify the target in
> CFLAGS and cc-option will fail to recognize target-specific options
> without it. Add CFLAGS to the CC invocation in cc-option.
> 
> The introduction of the realmode_bits variable is necessary to
> avoid make failing to build x86 due to CFLAGS referencing itself.
> 
> Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
> ---
> v2:
>  - Fixed x86 builds with the realmode_bits variable
> 
>  Makefile            | 2 +-
>  x86/Makefile.common | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 78352fced9d4..9dc5d2234e2a 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -21,7 +21,7 @@ DESTDIR := $(PREFIX)/share/kvm-unit-tests/
>  
>  # cc-option
>  # Usage: OP_CFLAGS+=$(call cc-option, -falign-functions=0, -malign-functions=0)
> -cc-option = $(shell if $(CC) -Werror $(1) -S -o /dev/null -xc /dev/null \
> +cc-option = $(shell if $(CC) $(CFLAGS) -Werror $(1) -S -o /dev/null -xc /dev/null \
>                > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
>  
>  libcflat := lib/libcflat.a
> diff --git a/x86/Makefile.common b/x86/Makefile.common
> index 0b7f35c8de85..e97464912e28 100644
> --- a/x86/Makefile.common
> +++ b/x86/Makefile.common
> @@ -98,6 +98,7 @@ tests-common = $(TEST_DIR)/vmexit.$(exe) $(TEST_DIR)/tsc.$(exe) \
>  ifneq ($(CONFIG_EFI),y)
>  tests-common += $(TEST_DIR)/realmode.$(exe) \
>  		$(TEST_DIR)/la57.$(exe)
> +realmode_bits := $(if $(call cc-option,-m16,""),16,32)
>  endif
>  
>  test_cases: $(tests-common) $(tests)
> @@ -108,7 +109,7 @@ $(TEST_DIR)/realmode.elf: $(TEST_DIR)/realmode.o
>  	$(LD) -m elf_i386 -nostdlib -o $@ \
>  	      -T $(SRCDIR)/$(TEST_DIR)/realmode.lds $^
>  
> -$(TEST_DIR)/realmode.o: bits = $(if $(call cc-option,-m16,""),16,32)
> +$(TEST_DIR)/realmode.o: bits = $(realmode_bits)
>  
>  $(TEST_DIR)/access_test.$(bin): $(TEST_DIR)/access.o
>  
> -- 
> 2.48.1
>