[Buildroot] [PATCH v2, 1/1] package/kvm-unit-tests: fix build without ssp on x86_64

[Arnout Vandecappelle]

On 26/05/2019 00:22, Fabrice Fontaine wrote:
> Makefile tries to detect stack-protector which will result in build
> failure on x86_64 if ssp is not available on host compiler so disable
> stack protector through EXTRA_CFLAGS
> 
> Fixes:
>  - http://autobuild.buildroot.org/results/e6f767755ffdb5ecc014eb5ad7519814f075a60e
> 
> Signed-off-by: Fabrice Fontaine <fontaine.fabrice at gmail.com>

 After more testing by Matt, applied to master with an updated commit message:

    package/kvm-unit-tests: fix build on Arch Linux x86_64

    On x86_64, we use the host compiler instead of the target compiler to
    build kvm-unit-tests, because it is built with -m32 and our target
    compiler doesn't support that.

    However, the compiler on Arch Linux is broken: it *always* builds with
    -fstack-protector, even when -ffreestanding is passed. However, when
    -fnostdlib is passed at link time (which is normally the case when
    building with -ffreestanding), it is not linked with the stack-protector
    library. This leads to a link time error:

    /usr/bin/ld: x86/realmode.o: in function `print_serial_u32':
    .../x86/realmode.c:104: undefined reference to `__stack_chk_fail'

    Since the entire package is built with -ffreestanding, it doesn't
    support stack-protector at all. Therefore, simply pass
    -fno-stack-protector explicitly on x86_64 to work around the bug in Arch
    Linux.

    Bug reported upstream: https://bugs.archlinux.org/task/64270


 Thanks everybody for investigating this.

 Regards,
 Arnout

> ---
> Changes v1 -> v2 (after review of Peter Korsgaard):
>  - Always disable stack-protector on x86_64 as we're using host compiler
> 
>  package/kvm-unit-tests/kvm-unit-tests.mk | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/package/kvm-unit-tests/kvm-unit-tests.mk b/package/kvm-unit-tests/kvm-unit-tests.mk
> index 92d67fb34b..72762d21f2 100644
> --- a/package/kvm-unit-tests/kvm-unit-tests.mk
> +++ b/package/kvm-unit-tests/kvm-unit-tests.mk
> @@ -37,6 +37,8 @@ KVM_UNIT_TESTS_CONF_OPTS =\
>  # x86-64 cannot do.
>  ifneq ($(BR2_x86_64),y)
>  KVM_UNIT_TESTS_CONF_OPTS += --cross-prefix="$(TARGET_CROSS)"
> +# Don't force -fstack-protector as we don't know if host compiler supports ssp 
> +KVM_UNIT_TESTS_MAKE_OPTS += EXTRA_CFLAGS=-fno-stack-protector
>  endif
>  
>  define KVM_UNIT_TESTS_CONFIGURE_CMDS
> @@ -44,11 +46,12 @@ define KVM_UNIT_TESTS_CONFIGURE_CMDS
>  endef
>  
>  define KVM_UNIT_TESTS_BUILD_CMDS
> -	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) standalone
> +	$(TARGET_MAKE_ENV) $(MAKE) $(KVM_UNIT_TESTS_MAKE_OPTS) -C $(@D) \
> +		standalone
>  endef
>  
>  define KVM_UNIT_TESTS_INSTALL_TARGET_CMDS
> -	$(TARGET_MAKE_ENV) $(MAKE) -C $(@D) \
> +	$(TARGET_MAKE_ENV) $(MAKE) $(KVM_UNIT_TESTS_MAKE_OPTS) -C $(@D) \
>  		DESTDIR=$(TARGET_DIR)/usr/share/kvm-unit-tests/ \
>  		install
>  endef
>