Rust cross-compile -lpcap from macos to linux - linux

I am trying to cross-compile my Rust project on Mac OS to Linux using cargo build --target=x86_64-unknown-linux-musl.
I installed the binary for Linux + musl cross-compilation on mac using brew install FiloSottile/musl-cross/musl-cross as I would ideally want a standalone binary.
I also installed the target using rustup target add x86_64-unknown-linux-gnu
And I have the following in my .cargo/config:
[target.x86_64-unknown-linux-musl]
linker = "x86_64-linux-musl-gcc"
However, I ran into issues with 2 libraries - sqlite3 and pcap:
= note: /usr/local/Cellar/musl-cross/0.9.8/libexec/bin/../lib/gcc/x86_64-linux-musl/6.4.0/../../../../x86_64-linux-musl/bin/ld: cannot find -lsqlite3
/usr/local/Cellar/musl-cross/0.9.8/libexec/bin/../lib/gcc/x86_64-linux-musl/6.4.0/../../../../x86_64-linux-musl/bin/ld: cannot find -lpcap
collect2: error: ld returned 1 exit status
I was able to solve the sqlite3 linker issue by adding features = ["bundled"] to my Cargo.toml file (similar to what is described here - https://users.rust-lang.org/t/linker-cannot-find-lsqlite3/23230/18) as that likely built it from source (which was great) but when I tried doing the same with pcap, it gave the following error:
the package `myProject` depends on `pcap`, with features: `bundled` but `pcap` does not have these features.
After reading somewhere I also tried (with low hopes) of providing the path to the installed libpcap on mac using RUSTPATH='-L/...' cargo build ... but that resulted, of course in undefined symbol errors.
Any ideas how can I get past this issue and cross compile my Rust project into a statically linked binary on macos to run on linux?

Cross compilation does not magically take care of libraries. You cannot just say "I want musl" and have something take care of all your dependencies.
The error message you are seeing is telling you exactly this: it cannot find libsqlite3 and libpcap.
The reason the error for sqlite disappears is because your sqlite library has a bundled feature, which replaces the linking with a built-in sqlite client. This, however, also requests the pcap bundled feature, which does not exist.
You have two options:
If you do not mind the performance loss in the bundled sqlite client, change your feature definition to target the feature of the dependency requiring sqlite
If you want the raw library itself, you will have to compile it for musl
No matter what happens, you will need to cross-compile libpcap for musl with the default sysroot provided by your musl compiler. As this varies per library, you will need to consult the libpcap documentation. once you have done so, you should be able to use the -lpcap flag, and the error will resolve itself.

Related

How to link mach-o format object files on linux?

I have been attempting to link a MACHO formatted object file on Linux, but I have failed miserably. So far, I have created the object file by running:
nasm -fmacho -o machoh.o hello.o
I have tried linking using:
clang --target=x86_64-apple-darwin machoh.o
but that failed. I have attempted using GCC, LD, and other linkers but I have still failed miserably. Are there any ideas on how I could solve my problem?
Thank you very much.
The most accessible solution would be lld, the LLVM linker.
lld does not ship with clang, but is a separate package.
sudo apt install lld
If you installed a version of clang that isn't the default (e.g. clang-12 explicitly), then you should use the same version for lld (i.e. lld-12).
Get a MacOS SDK from somewhere. This GitHub repo archives them.
If you're uncomfortable using the above, the "legitimate" way of obtaining it without a Mac would be:
Create an Apple ID
Go to https://developer.apple.com/download/all/
Download the "Command Line Tools for Xcode <version>"
Mount or extract the dmg
Extract the XAR package
For each ".pkg" folder inside, run pbzx <Payload | cpio -i
Find the Library/Developer/CommandLineTools/SDKs/MacOSX.sdk inside.
Feed both of the above to clang:
clang --target=x86_64-apple-darwin -fuse-ld=lld --sysroot=path/to/MacOSX.sdk machoh.o
I have tried linking using: clang --target=x86_64-apple-darwin machoh.o
but that failed.
Failed how? Details matter.
Anyway, there are 3 commonly used linkers on Linux: BFD-ld, Gold, and (newest) LLD.
Of these, Gold is an ELF-only linker, and will not work for Mach-O.
BFD-ld is only configured to support a few emulations (use ld --help to see which ones) in my distribution. BFD does appear to support Mach-O, so it's probably possible to build a Linux BFD-ld cross-linker with such support.
LLD should support Mach-O out of the box, but you are probably not using LLD.
So your first step should be to figure out which linker clang --target=x86_64-apple-darwin ... uses, and then make it use the one which does support Mach-O.

GCC linking wrong libpthread for build.rs

I'm attempting to cross-compile from Linux (NixOS) to Windows and encountering some frustrations.
There seem to be two parts that together are breaking the build:
Code in my Rust project requires multithreading, and as such requires a version of libpthread for Windows.
To build properly, I need a build.rs file. For some reason, Rust requires a version of libpthread for Linux for that.
What's the problem? Well, the build.rs has to be built with regular GCC and not MinGW because it needs to execute on my system. But for some reason, GCC is attempting to link to the Windows libpthread library instead of the system one, and as such is failing with an error about not supporting the library format.
(Failed) Alternatives
If I remove the build.rs, the project builds fine. Unfortunately, I need it for full functionality.
If I remove the Windows version of libpthread the build.rs builds and runs correctly, but MinGW fails with a missing library error when building the rest of the project.
Solution Paths?
Either I have to figure out why GCC's linking to the wrong version of libpthread, or I have to disable -lpthread entirely for the build.rs. I have no idea why it would need pthreads, considering for testing I stripped it down to only fn main() {}.
I have no idea where to start on either of these, and I've already spent a couple of days getting the problem down to this. I'd appreciate some help!

"undefined reference to `__stat_time64'" when cross-compiling rust project on musl 1.2.0

I'm trying to cross-compile a rust project for arm-linux-musleabihf and am hitting a linker error when using musl-cross-make. The rust project has a dependency on libgit2 and this is the dependency that seems to be causing the problem.
Using:
the latest rust (1.43.1 via rustup)
the arm-unknown-linux-musleabihf target
the latest musl-cross-make with TARGET=arm-linux-musleabihf
pointing TARGET_CC_linux_arm-unknown-linux-musleabihf and CARGO_TARGET_ARM_UNKNOWN_LINUX_MUSLEABIHF_LINKER at /opt/musl-cross-make/output/bin/arm-linux-musleabihf-gcc
I get an error when building:
error: linking with `/opt/musl-cross-make/output/bin/arm-linux-musleabihf-gcc` failed: exit code: 1
...
= note: /opt/musl-cross-make/output/bin/../lib/gcc/arm-linux-musleabihf/9.2.0/../../../../arm-linux-musleabihf/bin/ld: /tmp/rustcvSvGAJ/liblibgit2_sys-e56c2f9bd024a0a9.rlib(odb.o): in function `git_odb__add_default_backends':
odb.c:(.text.git_odb__add_default_backends+0x24): undefined reference to `__stat_time64'
/opt/musl-cross-make/output/bin/../lib/gcc/arm-linux-musleabihf/9.2.0/../../../../arm-linux-musleabihf/bin/ld: /tmp/rustcvSvGAJ/liblibgit2_sys-e56c2f9bd024a0a9.rlib(config.o): in function `git_config_add_file_ondisk':
config.c:(.text.git_config_add_file_ondisk+0x34): undefined reference to `__stat_time64'
/opt/musl-cross-make/output/bin/../lib/gcc/arm-linux-musleabihf/9.2.0/../../../../arm-linux-musleabihf/bin/ld: /tmp/rustcvSvGAJ/liblibgit2_sys-e56c2f9bd024a0a9.rlib(config_file.o): in function `config_file_read':
config_file.c:(.text.config_file_read+0x48): undefined reference to `__stat_time64'
...etc...
It looks like the linker is having difficulty resolving the musl-specific time64 symbols, and it's not clear why.
This works fine if:
I use the x86_64-linux-musl target on both rust and musl-cross-make
I build musl-cross-make with MUSL_VER=1.1.24
I also wrote a little C program that uses both time and stat, and this builds on musl 1.2.0 on the cross compiler without any issue.
What's going on here? What's special about libgit2 which means that it can't find the right __time64 symbols?
The problem is that the MUSL libc that ships with Rust versions up to and including 1.44 is MUSL libc 1.1.X based, not 1.2.0.
When Rust builds libgit2 is also needs to build libgit2-sys, which is C code. When building libgit2-sys it uses the MUSL libc version that you've built and installed yourself with musl-cross-make. This is 1.2.0 by default, which has reworked time_t 32/64 bit support, having a dependency on __stat_time64 and various other similarly named methods (such as __time64).
However, when Rust is linking your final application it is using the version of MUSL libc shipped with Rust for the x86_64-linux-musl target, which doesn't include that new time_t support, and doesn't have __stat_time64, __time64, etc. So the link fails.
Right now you have 2 options:
Use musl-cross-make to build 1.1.24 of MUSL lib. I'm not 100% what version is included with Rust 1.44. It may be 1.1.22, although from my own testing I found 1.1.24 works just fine (as have you).
Build your own version of Rust and/or the target liblibc.rlib with your own version of MUSL libc. I've never managed to successfully achieve this myself, although this might be a good place to start if you want to try this.
The general issue of using libc shipped with Rust, instead of a locally provided version, is being worked on, e.g. here.
You could try the instructions listed in https://github.com/richfelker/libcompat_time32:
Add -Wl,--whole-archive -lcompat_time32 -Wl,--no-whole-archive to the link command line. Special hacks (like prepending -Wl, to -lcompat_time32) may be needed if libtool is intercepting and mangling the command line.
I would recommend trying out https://github.com/rust-embedded/cross : it sets up the environment for cross-compilation in docker and seamlessly works, even for the case highlighted here.
AFAICT, they recompile musl with the correct version.

Cross Compilation of OpenCV for ARM fails

I am following this site to compile OpenCV for ARM.
It could not find my compiler so i hardcoded it into cmake file
find_program(CMAKE_C_COMPILER NAMES arm-linux-gnueabi-gcc-4.7)
find_program(CMAKE_CXX_COMPILER NAMES arm-linux-gnueabi-g++-4.7)
set(ARM_LINUX_SYSROOT /usr/arm-linux-gnueabi CACHE PATH "ARM cross compilation system root")
It compiles to aproximately 50% and then throws the following error:
Linking CXX shared library ../../lib/libopencv_viz.so
/usr/lib/libvtkCharts.so.5.8.0: file not recognized: File format not recognized
collect2: error: ld returned 1 exit status
I am not every experienced in cross compilation (or straight compilation for the matter). How do i fix this?
I think it is a mismatch between libopencv_viz and libvtkCharts. Some of your 3rdparty libs are built for another platform. These libraries themselves must be recompiled from source to match the details (ABI, dynamic system library dependencies, etc) of the system on which they are intended to be used.
Compiling OpenCV 2.4.10 worked for me. I did not have any preferred version. If you want to compile v3.0 see #Kornel's answer, that suggests to leave viz library out of compilation.
Use this command to checkout v2.4.10
git checkout 2.4.10

crosscompile glibc for arm

Good day
Currently, I'm working on an embedded device based on arm-linux. I want to build GCC for my target architecture with Glibc. GCC builds successful, but I have trouble with Glibc build.
I use the latest version of Glibc (ftp.gnu.org/gnu/glibc/glibc-2.12.1.tar.gz) and port for them (ftp.gnu.org/gnu/glibc/glibc-ports-2.12.1.tar.gz)
my configuration line:
../../glibc-2.12.1/configure --host=arm-none-linux-gnueabi --prefix=/home/anatoly/Desktop/ARM/build/glibc-build --enable-add-ons --with-binutils=/home/anatoly/Desctop/ARM/toolchain/arm/bin/
configuration script work fine, but i get some compile error:
...
/home/anatoly/Desktop/ARM/src/glibc-2.12.1/malloc/libmemusage_pic.a(memusage.os): In function me':
/home/anatoly/Desktop/ARM/src/glibc-2.12.1/malloc/lmemusage.c:253: undefined reference to__eabi+read_tp'
...
I also tried using the old version (2.11, 2.10) but have the same error.
Does anybody know the solution for this problem?
Use a precompiled toolchain, like those provided by code sourcery.
If you want to make your own, optimised (premature optimization is the root of all evil), use crosstool-NG, which is a tool dedicated to cross-compilation toolchain building.
If you are not convinced, and want to do everything with your own hands, ask your question on the crosstool-NG mailing list.
Try substituting arm-linux-gnueabi for arm-none-linux-gnueabi. Check that a compiler, loader etc. with the prefix you used for "host" exist on your path.

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