Created attachment 295060 [details] [review]
Suggested fix for build incompatibility with amd64 multilib Gentoo

This is issue from issue #537084 on bugs.gentoo.org (https://bugs.gentoo.org/show_bug.cgi?id=537084).


gstreamer-vaapi-0.5.9 has its own multilib support, which inteferes with Gentoo's. If it detects that you're trying to cross-compile 32-bit binaries on a 64-bit machine, it does this in ext/libvpx/upstream/build/make/configure.sh near line 1064:

            gcc*)
                add_cflags -m${bits}
                add_ldflags -m${bits}
                link_with_cc=gcc
                tune_cflags="-march="
                setup_gnu_toolchain

In this case, gstreamer-vaapi-0.5.9 want to use gcc as ld.

Moreover, the setup_gnu_toolchain() function in the same configure.sh is defined as:

    setup_gnu_toolchain() {
            CC=${CC:-${CROSS}gcc}
            CXX=${CXX:-${CROSS}g++}
            AR=${AR:-${CROSS}ar}
            LD=${LD:-${CROSS}${link_with_cc:-ld}}
            AS=${AS:-${CROSS}as}
        STRIP=${STRIP:-${CROSS}strip}
        NM=${NM:-${CROSS}nm}
            AS_SFX=.s
            EXE_SFX=
    }

and because link_with_cc ist set, it would set LD to ${CROSS}${link_with_cc} *if* LD is not already set.  However, portage sets LD in the multilib.eclass file near line 441 (source at http://sources.gentoo.org/cgi-bin/viewvc.cgi/gentoo-x86/eclass/multilib.eclass?diff_format=s&revision=1.106&view=markup):

    426 	# We want to avoid the behind-the-back magic of gcc-config as it
    427 	# screws up ccache and distcc. See #196243 for more info.
    428 	if [[ ${ABI} != ${DEFAULT_ABI} ]] ; then
    429 	# Back that multilib-ass up so we can restore it later
    430 	for v in CHOST CBUILD AS CC CXX LD PKG_CONFIG_{LIBDIR,PATH} ; do
    431 	vv="_abi_saved_${v}"
    432 	[[ ${!v+set} == "set" ]] && export ${vv}="${!v}" || unset ${vv}
    433 	done
    434 	export _DEFAULT_ABI_SAVED="true"
    435 	
    436 	# Set the CHOST native first so that we pick up the native
    437 	# toolchain and not a cross-compiler by accident #202811.
    438 	export CHOST=$(get_abi_CHOST ${DEFAULT_ABI})
    439 	export CC="$(tc-getCC) $(get_abi_CFLAGS)"
    440 	export CXX="$(tc-getCXX) $(get_abi_CFLAGS)"
    441 	export LD="$(tc-getLD) $(get_abi_LDFLAGS)"
    442 	export CHOST=$(get_abi_CHOST $1)
    443 	export CBUILD=$(get_abi_CHOST $1)
    444 	export PKG_CONFIG_LIBDIR=${EPREFIX}/usr/$(get_libdir)/pkgconfig
    445 	export PKG_CONFIG_PATH=${EPREFIX}/usr/share/pkgconfig
    446 	fi

This results in the following invocation of ld (line breaks added for readability):
    x86_64-pc-linux-gnu-ld -m elf_i386 -Wl,-O1 -Wl,--as-needed -m32 -g \
    -o /var/tmp/portage/media-plugins/gst-plugins-vaapi-0.5.9/temp/vpx-conf-11731-29273.x \
    /var/tmp/portage/media-plugins/gst-plugins-vaapi-0.5.9/temp/vpx-conf-11731-29273.o -lpthread

A suggested fix is given in comment #3 of the Gentoo issue.  I have attached it here as well.