| Message ID | 20180530121922.22122-2-npiggin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2018-05-30 21:19 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> > > Since v1: reworded changelog to explain the cause of the problem (thanks > Segher) and moved the flags into the 64-32 cross compile case. > --- > arch/powerpc/Makefile | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > index 95813df90801..d628724087c6 100644 > --- a/arch/powerpc/Makefile > +++ b/arch/powerpc/Makefile > @@ -24,6 +24,14 @@ 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 > > -- > 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 All applied to linux-kbuild/kconfig. Thanks!
2018-05-30 21:19 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. When I applied this patch, I changed the following. "th" -> "the" Please let me know if my fix-up is bad. > Cc: Segher Boessenkool <segher@kernel.crashing.org> > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > > Since v1: reworded changelog to explain the cause of the problem (thanks > Segher) and moved the flags into the 64-32 cross compile case. > --- > arch/powerpc/Makefile | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile > index 95813df90801..d628724087c6 100644 > --- a/arch/powerpc/Makefile > +++ b/arch/powerpc/Makefile > @@ -24,6 +24,14 @@ 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 > > -- > 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 Wed, 2018-05-30 at 12:19:19 UTC, Nicholas Piggin wrote: > 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> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/4bf4f42a2febb449a5cc5d79e7c58e cheers -- 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..d628724087c6 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -24,6 +24,14 @@ 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
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> Since v1: reworded changelog to explain the cause of the problem (thanks Segher) and moved the flags into the 64-32 cross compile case. --- arch/powerpc/Makefile | 8 ++++++++ 1 file changed, 8 insertions(+)