[U-Boot] [PATCH] Makefile: Introduce ARCH_PLATFORM_LIBGCC variable

[Tom Rini <trini@ti.com>]

On Sat, Oct 12, 2013 at 09:43:33AM +0200, Albert ARIBAUD wrote:
> Hi Tom,
> 
> On Fri, 11 Oct 2013 16:13:03 -0400, Tom Rini <trini@ti.com> wrote:
> 
> > In some cases, such as arm multi-lib hardfloat (hf) toolchains, we will
> > have multiple libgcc.a's available, and the arch needs to provide
> > additional logic to determine the right file to use
> > (-print-libgcc-file-name contains no CFLAG parsing logic).
> > 
> > Cc: Albert Aribaud <albert.u.boot@aribaud.net>
> > Signed-off-by: Tom Rini <trini@ti.com>
> > ---
> >  Makefile           |    4 ++++
> >  arch/arm/config.mk |   11 +++++++++++
> >  2 files changed, 15 insertions(+)
> > 
> > diff --git a/Makefile b/Makefile
> > index b09bfcc..13b396f 100644
> > --- a/Makefile
> > +++ b/Makefile
> > @@ -357,8 +357,12 @@ else
> >  PLATFORM_LIBGCC = -L $(USE_PRIVATE_LIBGCC) -lgcc
> >  endif
> >  else
> > +ifneq ("$(ARCH_PLATFORM_LIBGCC)","")
> > +PLATFORM_LIBGCC := -L $(shell dirname $(ARCH_PLATFORM_LIBGCC)) -lgcc
> > +else
> >  PLATFORM_LIBGCC := -L $(shell dirname `$(CC) $(CFLAGS) -print-libgcc-file-name`) -lgcc
> >  endif
> > +endif
> >  PLATFORM_LIBS += $(PLATFORM_LIBGCC)
> >  export PLATFORM_LIBS
> >  
> > diff --git a/arch/arm/config.mk b/arch/arm/config.mk
> > index d0cf43f..e1d0dec 100644
> > --- a/arch/arm/config.mk
> > +++ b/arch/arm/config.mk
> > @@ -19,6 +19,17 @@ LDFLAGS_FINAL += --gc-sections
> >  PLATFORM_RELFLAGS += -ffunction-sections -fdata-sections \
> >                       -fno-common -ffixed-r9 -msoft-float
> >  
> > +#
> > +# When we use a hardfp toolchain if there are both 'libgcc.a' (hardfp) and
> > +# 'arm-linux-gnueabi/libgcc.a' (softfp) we need to use the latter.  We
> > +# cannot always build with a hardfp-only toolchain.
> 
> What does this last sentence mean exactly?

What it says.  If a hardfp only toolchain is used certain targets shall
not link.  I had Marek confirm this as well.  I don't have the exact
logs handy, but today there's a few targets that will fail, and the nand
flash patchset introduces another because we enforce -msoft-float on
U-Boot, and rely on libgcc from the toolchain for certain functions
(__udivdi3 for example).

I don't know how you weren't making this fail on ELDK 5.x armv7a-fp, but
I was and the Linaro 2013.03 toolchain also will show this problem.
Once I push the nand PR (shortly), building for am3517_crane for example
will fail without this patch.

-- 
Tom
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