The 05/19/2020 17:38, Nick Desaulniers wrote: > sorry, hit tab/enter too soon... > > On Tue, May 19, 2020 at 5:37 PM Nick Desaulniers > <[email protected]> wrote: > > > > On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <[email protected]> wrote: > > > > > > Szabolcs Nagy ran into a kernel build failure with a custom gcc > > > toochain that sets -mfpu=auto -mfloat-abi=hard: > > > > > > /tmp/ccmNdcdf.s:1898: Error: selected processor does not support `cpsid > > > i' in ARM mode > > > > > > The problem is that $(call cc-option, -march=armv7-a) fails before the > > > kernel overrides the gcc options to also pass -msoft-float. > > > > The call to `$(call cc-option, -march=armv7-a) is th > > The call to `$(call cc-option, -march=armv7-a) is the one that fails or...?
the flag -march=armv7-a is invalid if the float abi is hard and no fpu is specified (since gcc-8). either an fpu should be specified or -march=armv7-a+fp (my toolchain was configured with the latter and it does not work if the kernel overrides it with -march=armv7-a) because of this cc-option failure the kernel goes on to pass nonsense flags everywhere (-march=armv5t) and some compilation eventually fails with an asm error. > > > > > > Move the option to the beginning the Makefile, before we call > > > > beginning of the > > > > > cc-option for the first time. > > > > > > Reported-by: Szabolcs Nagy <[email protected]> > > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 > > > Signed-off-by: Arnd Bergmann <[email protected]> > > > > Moving this looks harmless enough, though it's not clear to me how the > > failure you're describing would occur. I don't see calls to as-instr > > in arch/arm/Makefile. Which object is being built before -msoft-float > > is being set? > > ... ^ > > > > > > --- > > > arch/arm/Makefile | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > > > index 7d5cd0f85461..e428ea6eb0fa 100644 > > > --- a/arch/arm/Makefile > > > +++ b/arch/arm/Makefile > > > @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8 > > > KBUILD_LDFLAGS_MODULE += --be8 > > > endif > > > > > > +KBUILD_CFLAGS += -msoft-float > > > + > > > ifeq ($(CONFIG_ARM_MODULE_PLTS),y) > > > KBUILD_LDS_MODULE += $(srctree)/arch/arm/kernel/module.lds > > > endif > > > @@ -135,7 +137,7 @@ AFLAGS_ISA :=$(CFLAGS_ISA) > > > endif > > > > > > # Need -Uarm for gcc < 3.x > > > -KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call > > > cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) > > > -msoft-float -Uarm > > > +KBUILD_CFLAGS +=$(CFLAGS_ABI) $(CFLAGS_ISA) $(arch-y) $(tune-y) $(call > > > cc-option,-mshort-load-bytes,$(call cc-option,-malignment-traps,)) -Uarm > > > KBUILD_AFLAGS +=$(CFLAGS_ABI) $(AFLAGS_ISA) $(arch-y) $(tune-y) > > > -include asm/unified.h -msoft-float > > > > > > CHECKFLAGS += -D__arm__ > > > -- > > > 2.26.2 > > > > > -- > Thanks, > ~Nick Desaulniers --
