GCC >=3.4.3 supports --with-system-libunwind option: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=8bdf23ae810238b3a11f4af286b4a3772fb7244f Code was moved in: https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=e59be7e3775cce7a65bfac5c9aeb5f76d42f539b --with-system-libunwind option has any effect only for ia64*-*-linux* targets. --without-system-libunwind is default. libgcc/config.host: https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/config.host;h=503ebb6be20cc2cd382fd5f8e21769acdb3e7d0c;hb=HEAD#l844 [[[ ia64*-*-linux*) # Don't use crtbeginT.o from *-*-linux* default. extra_parts="crtbegin.o crtend.o crtbeginS.o crtendS.o crtfastmath.o" tmake_file="$tmake_file ia64/t-ia64 ia64/t-ia64-elf t-crtfm t-softfp-tf ia64/t-softfp t-softfp ia64/t-softfp-compat ia64/t-eh-ia64 t-libunwind ia64/t-linux" if test x$with_system_libunwind != xyes ; then tmake_file="${tmake_file} t-libunwind-elf ia64/t-linux-libunwind" fi md_unwind_header=ia64/linux-unwind.h ;; ]]] libgcc/config/t-libunwind (used on ia64*-*-linux* always): https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/config/t-libunwind;h=5244928da3c6b06cd785daf88d48d65194e7920b;hb=HEAD libgcc/config/t-libunwind-elf (used on ia64*-*-linux* only when building internal libunwind.so): https://gcc.gnu.org/git/?p=gcc.git;a=blob;f=libgcc/config/t-libunwind-elf;h=d07895bb6eb28e6c3c328d11bbc06b0d8ee64012;hb=HEAD I suggest that: --with-system-libunwind be passed in GCC >=3.4.3 (on all architectures) Version-conditional dependency on "ia64? ( sys-libs/libunwind:0= )" be added libgcc_s.so is linked against some version of libunwind.so. gcc-config copies libgcc_s.so from active version of GCC to /lib, so, to avoid regression for users with /usr/lib on separate mountpoint than /lib, it will be necessary to change sys-libs/libunwind to install (with USE="split-usr") shared libraries to /lib instead of /usr/lib. It could be done only on IA64, but for simplicity I suggest to do it on all architectures. Changes in sys-libs/libunwind need to be co-ordinated with changes in gcc-config (bug #667020). The oldest ebuild of sys-devel/gcc keyworded on IA64 is 3.4.6-r2, so there is no need to make gcc-config support old GCC with internal libunwind.so.
Created attachment 588620 [details, diff] Patch This patch applies after patch from bug #693250. Before testing this patch, it is NECESSARY to apply patch for sys-devel/gcc-config from bug #667020. Otherwise gcc-config would delete libunwind.so required by newly built GCC.
The bug has been referenced in the following commit(s): https://gitweb.gentoo.org/proj/gcc-config.git/commit/?id=17c4c852f979668387b1b965d48470cb730df5b6 commit 17c4c852f979668387b1b965d48470cb730df5b6 Author: Sergei Trofimovich <slyfox@gentoo.org> AuthorDate: 2019-09-04 18:59:31 +0000 Commit: Sergei Trofimovich <slyfox@gentoo.org> CommitDate: 2019-09-04 18:59:31 +0000 gcc-config: clarify why libunwind.so* is needed at all Bug: https://bugs.gentoo.org/667020 Bug: https://bugs.gentoo.org/693252 Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> gcc-config | 5 +++++ 1 file changed, 5 insertions(+)
At least # EXTRA_ECONF=--with-system-libunwind emerge -v1 gcc yields gcc with desired properties. libunwind gets into a fun state when it's a dependency of itself. $ lddtree /usr/lib/libunwind.so.8 /usr/lib/libunwind.so.8 (interpreter => None) libc.so.6.1 => /lib/libc.so.6.1 ld-linux-ia64.so.2 => /lib/ld-linux-ia64.so.2 libgcc_s.so.1 => /usr/lib/gcc/ia64-unknown-linux-gnu/9.2.0/libgcc_s.so.1 libunwind.so.8 => /usr/lib/libunwind.so.8 libgcc_s.so.1 => !!! circular loop !!! Which should be fine at least on glibc. python and emerge still works to be able to fix the world. I did not notice any critical binaries or libraries in stage3. The details are a bit messy: preserved-libs does not keep libunwind.so.7 and instantly breaks most (every?) c++ application like eix. Full list of silently broken packages on a random ~arch chroot where a bunch of packages present: # qfile $(fgrep -Rl libunwind.so.7 /usr/bin /usr/lib 2>/dev/null) | awk '{print $1}' | sort -u app-arch/brotli: app-crypt/gpgme: app-misc/sphinx: app-portage/eix: app-text/hunspell: app-text/openjade: app-text/opensp: app-text/poppler: app-text/qpdf: dev-lang/swig: dev-libs/boehm-gc: dev-libs/boost: dev-libs/efl: dev-libs/gmp: dev-libs/icu: dev-libs/libical: dev-libs/libpcre: dev-libs/libsass: dev-libs/re2: dev-python/subunit: dev-util/cmake: dev-util/colm: dev-util/cppunit: dev-util/gperf: dev-util/ragel: dev-util/re2c: media-gfx/graphite2: media-libs/flac: media-libs/mesa: media-libs/woff2: net-libs/gnutls: net-libs/libproxy: net-libs/nghttp2: net-libs/webkit-gtk: net-print/cups: sys-apps/groff: sys-auth/polkit: sys-libs/db: sys-libs/ncurses: Full list of to be broken packages on a real full stable ia64 system: slyfox@guppy ~ $ qfile $(sudo fgrep -Rl libunwind.so.7 /bin /sbin /usr/bin /usr/sbin /lib /usr/lib 2>/dev/null) | awk '{print $1}' | sort -u app-editors/emacs app-portage/eix dev-libs/gmp dev-libs/libpcre dev-util/cmake dev-util/gperf dev-util/ninja dev-util/re2c net-libs/gnutls sys-apps/groff sys-apps/smartmontools sys-devel/gcc sys-devel/gettext sys-libs/db sys-libs/ncurses
