| Message ID | 20221118003057.3223394-1-nathan@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] ARM: Drop '-mthumb' from AFLAGS_ISA | expand |
On Fri, 18 Nov 2022 at 01:34, Nathan Chancellor <nathan@kernel.org> wrote: > > When building with CONFIG_THUMB2_KERNEL=y + a version of clang from > Debian using CROSS_COMPILE=arm-linux-gnueabihf-, the following warning > occurs frequently: > > <built-in>:383:9: warning: '__thumb2__' macro redefined [-Wmacro-redefined] > #define __thumb2__ 2 > ^ > <built-in>:353:9: note: previous definition is here > #define __thumb2__ 1 > ^ > 1 warning generated. > > Debian carries a downstream patch that changes the default CPU of the > arm-linux-gnueabihf target from 'arm1176jzf-s' (v6) to 'cortex-a7' (v7). > As a result, '-mthumb' defines both '__thumb__' and '__thumb2__'. The > define of '__thumb2__' via the command line was purposefully added to > catch a situation like this. > > In a similar vein as commit 26b12e084bce ("ARM: 9264/1: only use > -mtp=cp15 for the compiler"), do not add '-mthumb' to AFLAGS_ISA, as it > is already passed to the assembler via '-Wa,-mthumb' and '__thumb2__' is > already defined for preprocessing. > > Fixes: 1d2e9b67b001 ("ARM: 9265/1: pass -march= only to compiler") > Link: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/raw/622dbcbd40b316ed3905a2d25d9623544a06e6b1/debian/patches/930008-arm.diff > Reported-by: "kernelci.org bot" <bot@kernelci.org> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Tested-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> > --- > v2: > * Add Nick's review and test tags. > * Call out explicitly that CROSS_COMPILE=arm-linux-gnueabihf- is > needed to reproduce this issue in commit message (Nick). > * Fix dead link in commit message (Nick). > * Use the snapshot branch for the patch link, as the diff is more up > to date against upstream LLVM (Nick). > v1: https://lore.kernel.org/20221114225719.1657174-1-nathan@kernel.org/ > arch/arm/Makefile | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > index 357f0d9b8607..d1ebb746ff40 100644 > --- a/arch/arm/Makefile > +++ b/arch/arm/Makefile > @@ -131,8 +131,9 @@ endif > AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) > > ifeq ($(CONFIG_THUMB2_KERNEL),y) > -CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN) > +CFLAGS_ISA :=-Wa,-mimplicit-it=always $(AFLAGS_NOWARN) > AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb -D__thumb2__=2 > +CFLAGS_ISA +=-mthumb > else > CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN) > AFLAGS_ISA :=$(CFLAGS_ISA) > > base-commit: 0c52591d22e99759da3793f19249bbf45ad742bd > -- > 2.38.1 >
diff --git a/arch/arm/Makefile b/arch/arm/Makefile index 357f0d9b8607..d1ebb746ff40 100644 --- a/arch/arm/Makefile +++ b/arch/arm/Makefile @@ -131,8 +131,9 @@ endif AFLAGS_NOWARN :=$(call as-option,-Wa$(comma)-mno-warn-deprecated,-Wa$(comma)-W) ifeq ($(CONFIG_THUMB2_KERNEL),y) -CFLAGS_ISA :=-mthumb -Wa,-mimplicit-it=always $(AFLAGS_NOWARN) +CFLAGS_ISA :=-Wa,-mimplicit-it=always $(AFLAGS_NOWARN) AFLAGS_ISA :=$(CFLAGS_ISA) -Wa$(comma)-mthumb -D__thumb2__=2 +CFLAGS_ISA +=-mthumb else CFLAGS_ISA :=$(call cc-option,-marm,) $(AFLAGS_NOWARN) AFLAGS_ISA :=$(CFLAGS_ISA)
When building with CONFIG_THUMB2_KERNEL=y + a version of clang from Debian using CROSS_COMPILE=arm-linux-gnueabihf-, the following warning occurs frequently: <built-in>:383:9: warning: '__thumb2__' macro redefined [-Wmacro-redefined] #define __thumb2__ 2 ^ <built-in>:353:9: note: previous definition is here #define __thumb2__ 1 ^ 1 warning generated. Debian carries a downstream patch that changes the default CPU of the arm-linux-gnueabihf target from 'arm1176jzf-s' (v6) to 'cortex-a7' (v7). As a result, '-mthumb' defines both '__thumb__' and '__thumb2__'. The define of '__thumb2__' via the command line was purposefully added to catch a situation like this. In a similar vein as commit 26b12e084bce ("ARM: 9264/1: only use -mtp=cp15 for the compiler"), do not add '-mthumb' to AFLAGS_ISA, as it is already passed to the assembler via '-Wa,-mthumb' and '__thumb2__' is already defined for preprocessing. Fixes: 1d2e9b67b001 ("ARM: 9265/1: pass -march= only to compiler") Link: https://salsa.debian.org/pkg-llvm-team/llvm-toolchain/-/raw/622dbcbd40b316ed3905a2d25d9623544a06e6b1/debian/patches/930008-arm.diff Reported-by: "kernelci.org bot" <bot@kernelci.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> --- v2: * Add Nick's review and test tags. * Call out explicitly that CROSS_COMPILE=arm-linux-gnueabihf- is needed to reproduce this issue in commit message (Nick). * Fix dead link in commit message (Nick). * Use the snapshot branch for the patch link, as the diff is more up to date against upstream LLVM (Nick). v1: https://lore.kernel.org/20221114225719.1657174-1-nathan@kernel.org/ arch/arm/Makefile | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) base-commit: 0c52591d22e99759da3793f19249bbf45ad742bd