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

["Gao, Liming" <liming.gao@intel.com>]

I have no other comments. Reviewed-by: Liming Gao <liming.gao@intel.com>

> -----Original Message-----
> From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org]
> Sent: Friday, December 21, 2018 7:02 PM
> To: edk2-devel@lists.01.org
> Cc: Leif Lindholm <leif.lindholm@linaro.org>; Gao, Liming <liming.gao@intel.com>
> Subject: Re: [PATCH v2] BaseTools/tools_def ARM: use softfloat target for CLANG3x
> 
> On Thu, 20 Dec 2018 at 12:03, Ard Biesheuvel <ard.biesheuvel@linaro.org> 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>
> > ---
> > v2: improve commit log
> >
> 
> Liming, Leif: are there any remaining concerns with this patch?
> 
> 
> >  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
> >