Hi all: I am building a GCC 4.5.3 cross-compiler for an embedded PowerPC target, together with binutils-2.21 and newlib 1.19.0 . I have been careful to use the same CFLAGS for both the embedded application and for newlib, as they can change the ABI. I recently realised that some components from GCC (ligbcc, libstdc++) are also linked to the embedded application, so I should be using the same CFLAGS there too. I searched a little and found variables like LIBGCC2_CFLAGS, MULTILIB_EXTRA_OPTS and CRTSTUFF_T_CFLAGS, but I'm confused about which ones I should use. Can anybody help? I also wanted to compile all GCC's target components without optimisation, as I need to debug some problems I'm having between my crt0.asm and GCC's crtstuff.c , and the optimised code makes it rather difficult. I wonder how I could prevent GCC from adding -O2 to the code, or whether I could somehow specify -O0 at the end of the target flags for all GCC target components. Please copy me on the answer, as I'm not subscribed to this list. Thanks in advance, R. Diez