In multilib.eclass, multilib_toolchain_setup() overrides the environment variables PKG_CONFIG_LIBDIR, PKG_CONFIG_PATH, PKG_CONFIG_SYSTEM_INCLUDE_PATH, and PKG_CONFIG_SYSTEM_LIBRARY_PATH so that the .pc files for the correct ABI will be found and used, as follows: export PKG_CONFIG_LIBDIR=${EPREFIX}/usr/$(get_libdir)/pkgconfig export PKG_CONFIG_PATH=${EPREFIX}/usr/share/pkgconfig export PKG_CONFIG_SYSTEM_INCLUDE_PATH=${EPREFIX}/usr/include export PKG_CONFIG_SYSTEM_LIBRARY_PATH=${EPREFIX}/$(get_libdir):${EPREFIX}/usr/$(get_libdir) As a reminder, pkgconfig is normally called upon to find packages that have been installed into the *host* system — i.e., packages listed in DEPEND. The "Ebuild writing: Variables" page[1] describes the SYSROOT variable as "(EAPI=7) The absolute path to the root directory containing build dependencies satisfied by DEPEND" and ESYSROOT as "(EAPI=7) Shorthand for ${SYSROOT%/}${EPREFIX}/." (That latter definition seems to be wrong, as the value of ESYSROOT apparently does not always end in a slash.) [1] https://devmanual.gentoo.org/ebuild-writing/variables/ In order to support the use case of setting SYSROOT to a path other than / while building packages for ABIs other than the default ABI, it is necessary to change the above lines in multilib.eclass to: export PKG_CONFIG_LIBDIR=${ESYSROOT%/}/usr/$(get_libdir)/pkgconfig export PKG_CONFIG_PATH=${ESYSROOT%/}/usr/share/pkgconfig export PKG_CONFIG_SYSTEM_INCLUDE_PATH=${ESYSROOT%/}/usr/include export PKG_CONFIG_SYSTEM_LIBRARY_PATH=${ESYSROOT%/}/$(get_libdir):${ESYSROOT%/}/usr/$(get_libdir) (It is also necessary to set PKG_CONFIG_SYSROOT_DIR in make.conf, but that's left for the user to do.) The user story motivating this request: * My amd64 Gentoo installation in "/" uses a multilib profile but does not have any installed packages configured for non-default ABIs. * I have set up a chroot to host Steam (which requires 32-bit libraries) using `emerge --config-root=/chroot/steam --sysroot=/chroot/steam games-util/steam-launcher::steam-overlay`. * My /chroot/steam/etc/portage/make.conf contains: source /etc/portage/make.conf ROOT="/chroot/steam" SYSROOT="${ROOT}" CFLAGS="${CFLAGS} --sysroot=${SYSROOT}" CXXFLAGS="${CXXFLAGS} --sysroot=${SYSROOT}" LDFLAGS="${LDFLAGS} -Wl,-rpath-link,${SYSROOT}/usr/\\\$LIB" PKG_CONFIG_SYSROOT_DIR="${SYSROOT}" PKG_CONFIG_LIBDIR="${SYSROOT}/usr/lib64/pkgconfig" PKG_CONFIG_PATH="${SYSROOT}/usr/share/pkgconfig" LD_LIBRARY_PATH="${SYSROOT}/usr/lib64:${SYSROOT}/usr/lib" LD_RUN_PATH="${SYSROOT}/usr/\$LIB" ABI_X86="32" * The above is almost sufficient to successfully build all dependencies of games-util/steam-launcher. However, without my proposed changes to multilib.eclass, packages fail while configuring for the 32-bit ABI because they are trying to find their dependencies beneath "/" rather than beneath "/chroot/steam". * After I make the proposed changes to multilib.eclass, I am able to build all dependencies of games-util/steam-launcher successfully. * For Gentoo users who do not set SYSROOT, this proposed change will have no bearing. * This change could conceivably affect crossdev users, but I think typically crossdev sysroots do not support multilib anyway, so this change wouldn't affect them either.
