[Buildroot] [PATCH] gcc: disable fortran use of libquadmath

[Thomas Petazzoni]

On Fri, 11 Sep 2020 07:41:31 -0500
Matt Weber <matthew.weber at rockwellcollins.com> wrote:

> The GCC package has a default conf option of disabling libquadmath and
> the toolchain dependencies selectively enabled it if i386 / x64.
> 
> Fixes:
> https://gitlab.com/bootlin/toolchains-builder/-/jobs/729359622
> 
> This patch fixes a build failure when (GCC + glibc) is being built for
> the IBM Power8 arch and has libgfortran enabled + libquadmath disabled.
> The libgfortran has a code condition for __float128 and includes the
> quadmath headers. The bug occurs because Power8 has emulated
> float128 support. The fix per GCC options is to also set
> --disable-libquadmath-support which disables the
> __float128/libquadmath support in gcc/fortran and in libgfortran [1].
> 
> Another option to fix the build failure was to enable libquadmath for
> IBM Power8 (ISA 2.07), however this would be soft float based as the
> ISA 3.0+ (Power9) first supports native float128 [2][3].
> 
> [1] https://fortran.gcc.gnu.narkive.com/8uSfoKUS/patch-build-pr-46540-add-disable-libquadmath-disable-libquadmath-support
> [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66382#c7
> [3] https://gcc.gnu.org/onlinedocs/gcc/RS_002f6000-and-PowerPC-Options.html
> 
> Cc: Thomas Petazzoni <thomas.petazzoni at bootlin.com>
> Signed-off-by: Matthew Weber <matthew.weber at rockwellcollins.com>
> ---
>  package/gcc/gcc.mk | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied to master, thanks.

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com