| Message ID | 20200519220923.1601303-1-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: pass -msoft-float to gcc earlier | expand |
On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <arnd@arndb.de> 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) > > Move the option to the beginning the Makefile, before we call beginning of the > cc-option for the first time. > > Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com> > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 > Signed-off-by: Arnd Bergmann <arnd@arndb.de> 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 >
sorry, hit tab/enter too soon... On Tue, May 19, 2020 at 5:37 PM Nick Desaulniers <ndesaulniers@google.com> wrote: > > On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <arnd@arndb.de> 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 `$(call cc-option, -march=armv7-a) is the one that fails or...? > > > > > Move the option to the beginning the Makefile, before we call > > beginning of the > > > cc-option for the first time. > > > > Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com> > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Moving this looks harmless enough, though it's not clear to me how the > failure you're describing would occur. I don't see calls to as-instr > in arch/arm/Makefile. Which object is being built before -msoft-float > is being set? ... ^ > > > --- > > arch/arm/Makefile | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > > index 7d5cd0f85461..e428ea6eb0fa 100644 > > --- a/arch/arm/Makefile > > +++ b/arch/arm/Makefile > > @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8 > > KBUILD_LDFLAGS_MODULE += --be8 > > endif > > > > +KBUILD_CFLAGS += -msoft-float > > + > > ifeq ($(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 > >
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 > <ndesaulniers@google.com> wrote: > > > > On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <arnd@arndb.de> 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 `$(call cc-option, -march=armv7-a) is the one that fails or...? the flag -march=armv7-a is invalid if the float abi is hard and no fpu is specified (since gcc-8). either an fpu should be specified or -march=armv7-a+fp (my toolchain was configured with the latter and it does not work if the kernel overrides it with -march=armv7-a) because of this cc-option failure the kernel goes on to pass nonsense flags everywhere (-march=armv5t) and some compilation eventually fails with an asm error. > > > > > > Move the option to the beginning the Makefile, before we call > > > > beginning of the > > > > > cc-option for the first time. > > > > > > Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com> > > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > > Moving this looks harmless enough, though it's not clear to me how the > > failure you're describing would occur. I don't see calls to as-instr > > in arch/arm/Makefile. Which object is being built before -msoft-float > > is being set? > > ... ^ > > > > > > --- > > > arch/arm/Makefile | 4 +++- > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > > > index 7d5cd0f85461..e428ea6eb0fa 100644 > > > --- a/arch/arm/Makefile > > > +++ b/arch/arm/Makefile > > > @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8 > > > KBUILD_LDFLAGS_MODULE += --be8 > > > endif > > > > > > +KBUILD_CFLAGS += -msoft-float > > > + > > > ifeq ($(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
On Wed, May 20, 2020 at 1:36 AM Szabolcs Nagy <szabolcs.nagy@arm.com> wrote: > > 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 > > <ndesaulniers@google.com> wrote: > > > > > > On Tue, May 19, 2020 at 3:09 PM Arnd Bergmann <arnd@arndb.de> 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 `$(call cc-option, -march=armv7-a) is the one that fails or...? > > the flag -march=armv7-a is invalid if the float abi > is hard and no fpu is specified (since gcc-8). > > either an fpu should be specified or -march=armv7-a+fp > (my toolchain was configured with the latter and it does > not work if the kernel overrides it with -march=armv7-a) > > because of this cc-option failure the kernel goes on to > pass nonsense flags everywhere (-march=armv5t) and some > compilation eventually fails with an asm error. Cool, thanks for the additional info. Arnd, if you wanted to include more of that snippet the commit message when submitting, I wouldn't complain. :) Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > > > > > > > > > Move the option to the beginning the Makefile, before we call > > > > > > beginning of the > > > > > > > cc-option for the first time. > > > > > > > > Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com> > > > > Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 > > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > > > > Moving this looks harmless enough, though it's not clear to me how the > > > failure you're describing would occur. I don't see calls to as-instr > > > in arch/arm/Makefile. Which object is being built before -msoft-float > > > is being set? > > > > ... ^ > > > > > > > > > --- > > > > arch/arm/Makefile | 4 +++- > > > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > > > > index 7d5cd0f85461..e428ea6eb0fa 100644 > > > > --- a/arch/arm/Makefile > > > > +++ b/arch/arm/Makefile > > > > @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8 > > > > KBUILD_LDFLAGS_MODULE += --be8 > > > > endif > > > > > > > > +KBUILD_CFLAGS += -msoft-float > > > > + > > > > ifeq ($(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) $(tune-y) -include asm/unified.h -msoft-float > > > > > > > > CHECKFLAGS += -D__arm__ > > > > -- > > > > 2.26.2 > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers > > --
diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 7d5cd0f85461..e428ea6eb0fa 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -16,6 +16,8 @@ LDFLAGS_vmlinux += --be8 KBUILD_LDFLAGS_MODULE += --be8 endif +KBUILD_CFLAGS += -msoft-float + ifeq ($(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__
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. Move the option to the beginning the Makefile, before we call cc-option for the first time. Reported-by: Szabolcs Nagy <szabolcs.nagy@arm.com> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87302 Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- arch/arm/Makefile | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)