export NIX_LDFLAGS+=" --build-id" export NIX_CFLAGS_COMPILE+=" -ggdb" dontStrip=1 fixupOutputHooks+=(_separateDebugInfo) _separateDebugInfo() { local dst="${debug:-$out}" if [ "$prefix" = "$dst" ]; then return; fi dst="$dst/lib/debug/.build-id" # Find executables and dynamic libraries. local -a files=($(find "$prefix" -type f -a \( -perm /0100 -o -name "*.so" -o -name "*.so.*" \))) local i magic for i in "${files[@]}"; do # Skip non-ELF files. exec 10< "$i" read -n 4 -u 10 magic exec 10<&- # Extract the Build ID. FIXME: there's probably a cleaner way. local id="$(readelf -n "$i" | sed 's/.*Build ID: \([0-9a-f]*\).*/\1/; t; d')" if [ "${#id}" != 40 ]; then echo "could not find build ID of $i, skipping" >&2 continue fi # Extract the debug info. header "separating debug info from $i (build ID $id)" mkdir -p "$dst/${id:0:2}" objcopy --only-keep-debug "$i" "$dst/${id:0:2}/${id:2}.debug" --compress-debug-sections strip --strip-debug "$i" done } # - We might prefer to compress the debug info during link-time already, # but our ld doesn't support --compress-debug-sections=zlib (yet). # - Debug info may cause problems due to excessive memory usage during linking. # Using -Wa,--compress-debug-sections should help with that; # further interesting information: https://gcc.gnu.org/wiki/DebugFission # - Another related tool: https://fedoraproject.org/wiki/Features/DwarfCompressor