Cross compile x86_64-unknown-linux-musl

[doitian]

I have tried https://github.com/emk/rust-musl-builder . The build failed on rocksdb.

[apiraino]

In theory the workflow to xcompile with musl should be easy:

# install the cross compiler
$ cargo install cross

# add the cargo target
$ rustup target add x86_64-unknown-linux-musl

# Finally, cross compile
# Some magic is happening here: a Docker image with musl
# is downloaded and executed to xcompile
$ cross build --release --target=x86_64-unknown-linux-musl

Unfortunately the last step fails, I guess it's related to rust-rocksdb/rust-rocksdb#174

Stacktrace

error: failed to run custom build command for `librocksdb-sys v5.18.3`
process didn't exit successfully: `/target/release/build/librocksdb-sys-ec5db74b9d3e7904/build-script-build` (exit code: 101)
--- stdout
cargo:rerun-if-changed=build.rs
cargo:rerun-if-changed=rocksdb/
cargo:rerun-if-changed=snappy/
cargo:rerun-if-changed=lz4/
cargo:rerun-if-changed=zstd/
cargo:rerun-if-changed=zlib/
cargo:rerun-if-changed=bzip2/

--- stderr
thread 'main' panicked at 'Unable to find libclang: "couldn\'t find any valid shared libraries matching: [\'libclang.so\', \'libclang-*.so\', \'libclang.so.*\'], set the `LIBCLANG_PATH` environment variable to a path where one of these files can be found (invalid: [])"', src/libcore/result.rs:997:5

Thanks to @wolf4ood for the hint ;-)

[doitian]

Error using emk/rust-musl-builder

error: failed to run custom build command for `librocksdb-sys v5.18.3`
process didn't exit successfully: `/home/rust/src/target/release/build/librocksdb-sys-dbb872178387f235/build-script-build` (exit code: 101)
--- stdout
cargo:rerun-if-changed=build.rs
cargo:rerun-if-changed=rocksdb/
cargo:rerun-if-changed=snappy/
cargo:rerun-if-changed=lz4/
cargo:rerun-if-changed=zstd/
cargo:rerun-if-changed=zlib/
cargo:rerun-if-changed=bzip2/

--- stderr
thread 'main' panicked at 'Unable to find libclang: "couldn\'t find any valid shared libraries matching: [\'libclang.so\', \'libclang-*.so\', \'libclang.so.*\'], set the `LIBCLANG_PATH` environment variable to a path where one of these files can be found (invalid: [])"', src/libcore/result.rs:997:5
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

warning: build failed, waiting for other jobs to finish...
error: failed to run custom build command for `jemalloc-sys v0.3.0`
process didn't exit successfully: `/home/rust/src/target/release/build/jemalloc-sys-129394ed5d2e2a14/build-script-build` (exit code: 101)
[...]
Makefile:386: recipe for target 'lib/libjemalloc.so.2' failed

--- stderr
configure: WARNING: using cross tools not prefixed with host triplet
ar: `u' modifier ignored since `D' is the default (see `U')
/usr/bin/ld: src/jemalloc.pic.o: relocation R_X86_64_32 against `.rodata.malloc_conf_init.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/arena.pic.o: relocation R_X86_64_32S against hidden symbol `_rjem_je_h_steps' can not be used when making a shared object
/usr/bin/ld: src/background_thread.pic.o: relocation R_X86_64_32S against hidden symbol `_rjem_je_h_steps' can not be used when making a shared object
/usr/bin/ld: src/base.pic.o: relocation R_X86_64_32S against hidden symbol `_rjem_je_sz_size2index_tab' can not be used when making a shared object
/usr/bin/ld: src/bin.pic.o: relocation R_X86_64_32 against `.rodata._rjem_je_bin_init.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/ckh.pic.o: relocation R_X86_64_32S against hidden symbol `_rjem_je_sz_size2index_tab' can not be used when making a shared object
/usr/bin/ld: src/ctl.pic.o: relocation R_X86_64_32 against `.rodata.super_arenas_bin_i_node' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/extent.pic.o: relocation R_X86_64_32 against undefined hidden symbol `_rjem_je_extents_rtree' can not be used when making a shared object
/usr/bin/ld: src/large.pic.o: relocation R_X86_64_32S against undefined hidden symbol `_rjem_je_arenas' can not be used when making a shared object
/usr/bin/ld: src/log.pic.o: relocation R_X86_64_32 against undefined hidden symbol `_rjem_je_log_var_names' can not be used when making a shared object
/usr/bin/ld: src/malloc_io.pic.o: relocation R_X86_64_32S against `.rodata._rjem_je_malloc_strtoumax' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/mutex.pic.o: relocation R_X86_64_32 against `.rodata._rjem_je_malloc_mutex_postfork_child.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/pages.pic.o: relocation R_X86_64_32 against `.rodata._rjem_je_pages_map.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/prof.pic.o: relocation R_X86_64_32 against `.rodata.prof_dump_open_impl.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/rtree.pic.o: relocation R_X86_64_32 against `.rodata._rjem_je_rtree_new.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/stats.pic.o: relocation R_X86_64_32S against `.rodata.mutex_stats_init_cols.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/tcache.pic.o: relocation R_X86_64_32S against undefined hidden symbol `_rjem_je_arenas' can not be used when making a shared object
/usr/bin/ld: src/tsd.pic.o: relocation R_X86_64_32 against `.rodata._rjem_je_tsd_cleanup.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: src/witness.pic.o: relocation R_X86_64_32 against `.rodata.witness_lock_error_impl.str1.8' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: final link failed: Nonrepresentable section on output
collect2: error: ld returned 1 exit status
make: *** [lib/libjemalloc.so.2] Error 1
make: *** Waiting for unfinished jobs....
thread 'main' panicked at 'command did not execute successfully: "make" "srcroot=../jemalloc/" "-j" "16"
expected success, got: exit code: 2', /root/.cargo/registry/src/github.com-1ecc6299db9ec823/jemalloc-sys-0.3.0/build.rs:370:9
note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

[doitian]

It's unlikely to build against musl now since rocksdb requires c++.

[apiraino]

I'm chasing down the maintainer of the japaric/x86_64-unknown-linux-musl Docker container to see if we can get it fixed there. I think it would be the best option (since cargo cross is well integrated in the building workflow.

[doitian]

I have tried a custom image with cargo cross. I have installed clang, g++, and made link musl-g++ to g++. The problem is rocksdb depends on c++ standard library heavily, we need a real c++ for musl to make it work.