Situation: I need to cross-compile an autoconfiscated library (libsecp256k1: https://github.com/bitcoin/secp256k1) for a couple of embedded systems (one ARM-based, one PPC-based). What I believe to be the Right Thing is to teach autoconf to use the vendor cross-compilers, vendor C libraries, firmware API libraries, etc., hopefully without having to fork and hack the library build system (...I hope), so I simply cross-compile the library and then link to it like I would anything else. The vendor cross-compilers are just (rather old) GCC versions built for the target architecture, so it seems that this should be a reasonably sane thing to do. I have the flags needed to correctly cross-compile our code for the target architectures, obviously, so I think I have all the tools in hand and just need to learn how to put them together. I found the Vaughan-Elliston-Tromey-Taylor book online as well as random internet sources of questionable provenance, but they usually don't go further than mentioning the build and host flags and don't discuss custom toolchains, custom C libraries, etc. I came up with the following first cut for the ARM build (snipped out of the makefile): LONG_ARCH = strongarm ./configure \ --build=`./build-aux/config.guess` \ --host $(LONG_ARCH)-codesafe-elf \ CC="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-gcc" \ AR="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-ar" \ RANLIB="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-ranlib" \ AS="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-as" \ LD="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-ld" \ NM="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-nm" \ STRIP="/opt/nfast/gcc/bin/$(LONG_ARCH)-codesafe-elf-strip So, hopefully, I've figured out how to set build and host (the host argument is obviously the prefix the vendor used when building the toolchain) and point autoconf at the correct toolchain. First problem--configure dies, reporting that "C compiler cannot create executables." I suspect this is related to the Second Problem. Second Problem: I don't know The Right Way to pass in the architecture flags to autoconf (-march, text segment address, etc.). I tried overriding CFLAGS with the values I use for my own code, but that didn't work. Plus, I suspect that I shouldn't simply set CFLAGS anyway, since the library build system presumably has some important opinions about that. I guess I simply want to add my architecture flags to the library's choices, not override. I tried appending them to the value of CC, but that failed as well. I imagine I'm missing some basic autoconf knowledge here. What basic piece of knowledge am I missing here? DLL _______________________________________________ Autoconf mailing list Autoconf@xxxxxxx https://lists.gnu.org/mailman/listinfo/autoconf
