https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92083
--- Comment #2 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Note also that glibc does not support being built with a different long double ABI from the default one. On architectures where more than one long double format is supported by glibc, either a format is paired with other ABI choices (mips, where long double is binary64 for the o32 ABI and binary128 for the other two ABIs), or more than one long double ABI is supported in the same glibc build and the headers automatically select different functions accordingly (alpha, powerpc, s390, 32-bit sparc; in the powerpc64le case, work is underway to support binary128 as a third long double format in a single glibc build, but much of that is not yet in glibc). x86 is not one of those architectures, so alternative long double formats are not supported for it in glibc at all. (Before NaCl died, I think Roland planned to add support for different formats for use by the x86 NaCl port, but that never got merged and all the Arm NaCl support was removed.)
