| Message ID | 20180516141458.18996-2-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2018-05-16 23:14 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>: > Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit > kernels, even with -m32. Debian's powerpc64le is one such case, and > that is because it is built with --with-cpu=power8. > > So when cross compiling a 32-bit kernel with a 64-bit toolchain, set > -mcpu=powerpc initially, which is the generic 32-bit powerpc machine > type and scheduling model. CPU and platform code can override this > with subsequent -mcpu flags if necessary. > > This is not done for 32-bit toolchains otherwise it would override > their defaults, which are presumably set appropriately for the > environment (moreso than a 64-bit cross compiler). > > This fixes a lot of build failures due to incompatible assembly when > compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain. > > Cc: Segher Boessenkool <segher@kernel.crashing.org> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- Can you please remove the noise changes? 1/4 adds some blank lines, then 2/4 removes them. > arch/powerpc/Makefile | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > index 95813df90801..15ca4bafad82 100644 > --- a/arch/powerpc/Makefile > +++ b/arch/powerpc/Makefile > @@ -24,9 +24,20 @@ ifeq ($(HAS_BIARCH),y) > ifeq ($(CROSS32_COMPILE),) > CROSS32CC := $(CC) -m32 > KBUILD_ARFLAGS += --target=elf32-powerpc > + This blank line will be removed by the next patch. > +ifdef CONFIG_PPC32 > +# These options will be overridden by any -mcpu option that the CPU > +# or platform code sets later on the command line, but they are needed > +# to set a sane 32-bit cpu target for the 64-bit cross compiler which > +# may default to the wrong ISA. > +KBUILD_CFLAGS += -mcpu=powerpc > +KBUILD_AFLAGS += -mcpu=powerpc > +endif > + This blank line will be removed by the next patch. > endif > endif > > + This blank line will be removed by the next patch. > export CROSS32CC CROSS32AR > > ifeq ($(CROSS_COMPILE),) > -- > 2.17.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, 29 May 2018 22:39:48 +0900 Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > 2018-05-16 23:14 GMT+09:00 Nicholas Piggin <npiggin@gmail.com>: > > Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit > > kernels, even with -m32. Debian's powerpc64le is one such case, and > > that is because it is built with --with-cpu=power8. > > > > So when cross compiling a 32-bit kernel with a 64-bit toolchain, set > > -mcpu=powerpc initially, which is the generic 32-bit powerpc machine > > type and scheduling model. CPU and platform code can override this > > with subsequent -mcpu flags if necessary. > > > > This is not done for 32-bit toolchains otherwise it would override > > their defaults, which are presumably set appropriately for the > > environment (moreso than a 64-bit cross compiler). > > > > This fixes a lot of build failures due to incompatible assembly when > > compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain. > > > > Cc: Segher Boessenkool <segher@kernel.crashing.org> > > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > --- > > > Can you please remove the noise changes? > > 1/4 adds some blank lines, then 2/4 removes them. Okay sure, I will change that. Thanks, Nick -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 95813df90801..15ca4bafad82 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -24,9 +24,20 @@ ifeq ($(HAS_BIARCH),y) ifeq ($(CROSS32_COMPILE),) CROSS32CC := $(CC) -m32 KBUILD_ARFLAGS += --target=elf32-powerpc + +ifdef CONFIG_PPC32 +# These options will be overridden by any -mcpu option that the CPU +# or platform code sets later on the command line, but they are needed +# to set a sane 32-bit cpu target for the 64-bit cross compiler which +# may default to the wrong ISA. +KBUILD_CFLAGS += -mcpu=powerpc +KBUILD_AFLAGS += -mcpu=powerpc +endif + endif endif + export CROSS32CC CROSS32AR ifeq ($(CROSS_COMPILE),)
Some 64-bit toolchains uses the wrong ISA variant for compiling 32-bit kernels, even with -m32. Debian's powerpc64le is one such case, and that is because it is built with --with-cpu=power8. So when cross compiling a 32-bit kernel with a 64-bit toolchain, set -mcpu=powerpc initially, which is the generic 32-bit powerpc machine type and scheduling model. CPU and platform code can override this with subsequent -mcpu flags if necessary. This is not done for 32-bit toolchains otherwise it would override their defaults, which are presumably set appropriately for the environment (moreso than a 64-bit cross compiler). This fixes a lot of build failures due to incompatible assembly when compiling 32-bit kernel with th Debian powerpc64le 64-bit toolchain. Cc: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> --- arch/powerpc/Makefile | 11 +++++++++++ 1 file changed, 11 insertions(+)