Created attachment 887367 [details] build.log of the failed cross-compile attempt When cross-compiling dev-lang/rust-1.75.0-r1 for aarch64-unknown-linux-gnu, the compilation failed with the following error: ``` running: "cc" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-march=armv8-a+crypto+crc" "-mtune=cortex-a72.cortex-a53" "-mfix-cortex-a53-835769" "-mfix-cortex-a53-843419" "-pipe" "-fno-builtin" "-fvisibility=hidden" "-ffreestanding" "-DVISIBILITY_HIDDEN" "-o" "/usr/aarch64-unknown-linux-gnu/tmp/portage/dev-lang/rust-1.75.0-r1/work/rustc-1.75.0-src/build/x86_64-unknown-linux-gnu/stage0-std/x86_64-unknown-linux-gnu/release/build/compiler_builtins-c76748dc165629dc/out/5e8c8d8503d8d0b7-absvdi2.o" "-c" "/usr/aarch64-unknown-linux-gnu/tmp/portage/dev-lang/rust-1.75.0-r1/work/rustc-1.75.0-src/src/llvm-project/compiler-rt/lib/builtins/absvdi2.c" cargo:warning=cc: error: unrecognized command-line option ‘-mfix-cortex-a53-835769’ cargo:warning=cc: error: unrecognized command-line option ‘-mfix-cortex-a53-843419’ exit status: 1 ``` The reason is that the build system uses CHOST CFLAGS with the CBUILD toolchain. An identical failure was observed when cross-compiling to ppc and ppc64 hosts, so it is arch-independent. The ebuild environment file contains the correct flags: ``` declare -x BUILD_CFLAGS="-O2 -ggdb -march=znver1 -pipe" declare -x BUILD_CPPFLAGS="" declare -x BUILD_CXXFLAGS="-O2 -ggdb -march=znver1 -pipe" declare -x BUILD_LDFLAGS="-Wl,-O1 -Wl,--as-needed" declare -x CBUILD="x86_64-pc-linux-gnu" declare -x CCASFLAGS="" declare -x CFLAGS="-O2 -march=armv8-a+crypto+crc -mtune=cortex-a72.cortex-a53 -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -pipe" declare -x CFLAGS_aarch64_unknown_linux_gnu="" declare -x CFLAGS_default declare -x CHOST="aarch64-unknown-linux-gnu" declare -x CHOST_arm64="aarch64-unknown-linux-gnu" declare -x CHOST_default="aarch64-unknown-linux-gnu" declare -x CPPFLAGS="" declare -x CTARGET_default="aarch64-unknown-linux-gnu" declare -x CXXFLAGS="-O2 -march=armv8-a+crypto+crc -mtune=cortex-a72.cortex-a53 -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -pipe" declare -x DEFAULT_ABI="arm64" ``` But when the build system prints the flags it used during compilation, CFLAGS_x86_64-unknown-linux-gnu and CXXFLAGS_x86_64-unknown-linux-gnu are wrongly set to the host (arm64) CFLAGS, while CFLAGS_aarch64-unknown-linux-gnu is wrongly set to empty defaults; only CXXFLAGS_aarch64-unknown-linux-gnu are correct: ``` CC_aarch64-unknown-linux-gnu = "aarch64-unknown-linux-gnu-gcc" CFLAGS_aarch64-unknown-linux-gnu = ["-ffunction-sections", "-fdata-sections", "-fPIC"] CXX_aarch64-unknown-linux-gnu = "aarch64-unknown-linux-gnu-g++" CXXFLAGS_aarch64-unknown-linux-gnu = ["-ffunction-sections", "-fdata-sections", "-fPIC", "-march=armv8-a+crypto+crc", "-mtune=cortex-a72.cortex-a53", "-mfix-cortex-a53-835769", "-mfix-cortex-a53-843419", "-pipe"] AR_aarch64-unknown-linux-gnu = "aarch64-unknown-linux-gnu-ar" CC_x86_64-unknown-linux-gnu = "cc" CFLAGS_x86_64-unknown-linux-gnu = ["-ffunction-sections", "-fdata-sections", "-fPIC", "-m64", "-march=armv8-a+crypto+crc", "-mtune=cortex-a72.cortex-a53", "-mfix-cortex-a53-835769", "-mfix-cortex-a53-843419", "-pipe"] CXX_x86_64-unknown-linux-gnu = "c++" CXXFLAGS_x86_64-unknown-linux-gnu = ["-ffunction-sections", "-fdata-sections", "-fPIC", "-m64", "-march=armv8-a+crypto+crc", "-mtune=cortex-a72.cortex-a53", "-mfix-cortex-a53-835769", "-mfix-cortex-a53-843419", "-pipe"] AR_x86_64-unknown-linux-gnu = "ar" ```
I forgot to mention an important thing: I am cross-compiling Rust using a cross-toolchain installed on CBUILD, i.e., with the `system-bootstrap` USE flag. This is not necessary for aarch64-unknown-linux-gnu, which can be bootstrapped from the upstream stage0, but the build fails in an identical manner when cross-compiling for tier3 hosts such as powerpc-gentoo-linux-musl, where system-bootstrap is the only possibility.
Can you give a set of commands to reproduce it?
Sure. If you already have the cross build environment set up (rust installed on the build with proper LLVM_TARGETS, crossdev set up), then it's this emerge: ``` USE='dist system-bootstrap' LLVM_TARGETS='X86' CFLAGS='-O2 -march=armv8-a+crypto+crc -mtune=cortex-a72.cortex-a53 -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -pipe' aarch64-unknown-linux-gnu-emerge -1 =dev-lang/rust-1.75.0-r1 ```
(In reply to jonys from comment #3) > Sure. If you already have the cross build environment set up (rust installed > on the build with proper LLVM_TARGETS, crossdev set up), then it's this > emerge: > ``` > USE='dist system-bootstrap' LLVM_TARGETS='X86' CFLAGS='-O2 > -march=armv8-a+crypto+crc -mtune=cortex-a72.cortex-a53 > -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -pipe' > aarch64-unknown-linux-gnu-emerge -1 =dev-lang/rust-1.75.0-r1 > ``` I was hoping for a full set of commands as someone who knows crossdev but has no idea about it with Rust yet.
(In reply to Sam James from comment #4) > I was hoping for a full set of commands as someone who knows crossdev but > has no idea about it with Rust yet. OK. For most of the steps, you can just follow the guide on the Gentoo Wiki: https://wiki.gentoo.org/wiki/Cross_build_environment ``` ## Crossdev setup # build the C cross toolchain crossdev -t aarch64-unknown-linux-gnu # edit /usr/aarch64-unknown-linux-gnu/etc/portage/make.conf and # 1. add CFLAGS="-O2 -march=armv8-a+crypto+crc -mtune=cortex-a72.cortex-a53 -mfix-cortex-a53-835769 -mfix-cortex-a53-843419 -pipe" # 2. add `-pam -su` to USE flags to prevent failures when emerging @system # set the profile ln -s /var/db/repos/gentoo/profiles/default/linux/arm64/17.0 /usr/aarch64-unknown-linux-gnu/etc/portage/make.profile # build the host system aarch64-unknown-linux-gnu-emerge -avu --keep-going @system ## Build system setup # build the Rust cross toolchain LLVM_TARGETS='AArch64 X86' USE=rust-src emerge -av1 dev-lang/rust ## Rust setup # bootstrap Rust on the host system using the Rust toolchain from above LLVM_TARGETS='AArch64 X86' USE='dist system-bootstrap' aarch64-unknown-linux-gnu-emerge -av1 =dev-lang/rust-1.75.0-r1 ``` I hope this list is complete – I can't fully test it without removing my cross toolchains first, which I'm reluctant to do.
