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Comment by tlb | Hacker News Reader

I'm suffering through this now -- I have a custom C++ Node exception that needs to run on both x64 and ARM. The ARM cpu is onboard a mobile robot, where I care about power draw.

The good news is that Clang can cross-compile fairly easily. Much better than gcc.

The bad news is that there are a surprising number of missing libraries on Ubuntu/ARM64. For example, Eigen3. And although the code is fairly compatible, there's some extra cognitive load in learning to debug on ARM. For example, calling a virtual function on a deleted object crashes differently.

I'm willing to put up with it for ARM's advantages in battery-powered applications, but I wouldn't just to save a few bucks on cloud servers.

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Have you tried compiling with address sanitizer? https://clang.llvm.org/docs/AddressSanitizer.html

Unfortunately C++ code is only portable if it is free from undefined behavior. Fortunately there are many tools now to debug these kinds of errors: https://blog.regehr.org/archives/1520

The Undefined Behavior Sanitizer might be more useful in this case: http://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html

How about using CMake to download and cross-compile the 3rd party dependencies? I've worked on a couple of robotics applications (C++). I wouldn't depend on Ubuntu for packages. You'll lose the flexibility to choose package versions, apply patches etc.

> The good news is that Clang can cross-compile fairly easily. Much better than gcc.

How so? The complications in cross compiling come from setting up all the system libraries, not the compiler and linker.

I remember getting annoyed needing a windows driver that was part of an open source package. That needed autotools to build. I got annoyed trying to make it compile under mysys/MinGW. So I built a gcc cross compiler under linux. Compiled the damn driver and it just worked(tm).

by default it supports a variety of targets, you don't need to set it up.

setting up the system libraries is relatively easy, make a copy of the target you're building for, assuming it has a setup for compilation, and use --sysroot=/path/to/target.

eigen3 is header only isn't it?

Yes, but only once you run the `configure` so that it chooses the right inline assembly blocks for your system.

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