Re: [PATCH v2] BaseTools/tools_def ARM: use softfloat target for CLANG3x

[Leif Lindholm <leif.lindholm@linaro.org>]

On Thu, Dec 20, 2018 at 12:03:32PM +0100, Ard Biesheuvel wrote:
> The 'arm-linux-gnueabihf' target triplet we use for CLANG35 and
> CLANG38 specifies a hardfloat target, and so the binaries that are
> emitted are annotated as using VFP registers for passing floating
> point arguments, even though no VFP is used anywhere in the code.
> 
> This works fine as long as we don't try to link against code
> that uses software floating point, but combining object files
> with different floating point calling conventions is not permitted.
> 
> So switch to the softfloat arm-linux-gnueabi triplet instead.
> This affects both the name Clang uses when invoking the linker,
> and the arguments it passes to it, and we are mostly interested
> in the latter (since any version of GNU ld.bfd will do the right
> thing as long as it targets EABI ARM)
> 
> For native builds, this change has no effect, since the unprefixed
> system linker will take priority, and so Clang will pass the right
> arguments to whichever linker happens to be the system linker.
> 
> For cross builds, the fact that Clang composes the name of the
> linker by prefixing '-ld' with the target triplet implies that
> users will have to switch to a version of binutils that targets
> arm-linux-gnueabi rather than arm-linux-gnueabihf. Note that the
> GCCx toolchain targets can use either when building for ARM so this
> does not create a need to install two versions of the ARM cross
> toolchain. Also, note that all ARM toolchains in the GCC family
> are already documented as requiring a toolchain that targets
> arm-linux-gnueabi and not arm-linux-gnueabihf.
> 
> Contributed-under: TianoCore Contribution Agreement 1.1
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

> ---
> v2: improve commit log
> 
>  BaseTools/Conf/tools_def.template | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template
> index 902680c24c85..f7eb87af14c2 100755
> --- a/BaseTools/Conf/tools_def.template
> +++ b/BaseTools/Conf/tools_def.template
> @@ -5231,7 +5231,7 @@ RELEASE_GCC5_AARCH64_DLINK_XIPFLAGS = -z common-page-size=0x20
>  *_CLANG35_*_DLINK_PATH           = ENV(CLANG35_BIN)clang
>  *_CLANG35_*_ASLDLINK_PATH        = ENV(CLANG35_BIN)clang
>  
> -DEFINE CLANG35_ARM_TARGET        = -target arm-linux-gnueabihf
> +DEFINE CLANG35_ARM_TARGET        = -target arm-linux-gnueabi
>  DEFINE CLANG35_AARCH64_TARGET    = -target aarch64-linux-gnu
>  
>  DEFINE CLANG35_WARNING_OVERRIDES = -Wno-parentheses-equality -Wno-tautological-compare -Wno-tautological-constant-out-of-range-compare -Wno-empty-body -Wno-unknown-warning-option
> @@ -5384,7 +5384,7 @@ NOOPT_CLANG38_X64_DLINK2_FLAGS     = DEF(GCC5_X64_DLINK2_FLAGS) -O0
>  ##################
>  # CLANG38 ARM definitions
>  ##################
> -DEFINE CLANG38_ARM_TARGET        = -target arm-linux-gnueabihf
> +DEFINE CLANG38_ARM_TARGET        = -target arm-linux-gnueabi
>  DEFINE CLANG38_ARM_CC_FLAGS      = DEF(GCC_ARM_CC_FLAGS) DEF(CLANG38_ARM_TARGET) DEF(CLANG38_WARNING_OVERRIDES) -mno-movt
>  DEFINE CLANG38_ARM_DLINK_FLAGS   = DEF(CLANG38_ARM_TARGET) DEF(GCC_ARM_DLINK_FLAGS)
>  
> -- 
> 2.19.2
>