[chrisseaton]

But why would you want to recompile the VM when you've just changed your program?

And it looks like you can cross compile BEAM anyway. http://erlang.org/faq/implementations.html. It's just a C program isn't it so why wouldn't you be able to?

[GrinningFool]

The ERTS runtime (VM + libraries) are taken from the host and are not built. That said, it is possible to build the runtime for other platforms via cross compilation. [1][2]. I've done this for ARM, but have not tried to generate a release using the cross-platform build.

The beams themselves are cross-platform bytecode, but in practice beam files are not distributed on their own (except for patching). Typically you'll ship them as part of the released package which includes ERTS, your application, and all required dependencies (system libraries, other apps/libraries, and any native dependencies you've introduced). It excludes anything you don't declare as necessary from the final release package

In practice, people will usually use either the official release tooling or third party tooling to create platform-specific releases.

[1] http://erlang.org/doc/installation_guide/INSTALL-CROSS.html [2] http://www2.erlangcentral.org/wiki/?title=Cross_compiling

[gamache]

You're not recompiling the VM, you're just including a copy of it in the release tarball, so that you can copy the tarball to any machine with the same architecture and run it regardless of whether Erlang or Elixir is installed globally on the machine.

The goal of a release is to bundle together everything you need -- your program, the VM that runs it, your config files, and any instructions necessary to upgrade/downgrade from another version of your code.

[xxxx00998978]

He means why not just include the apropiate vm as a binary for any given arch.

[chrisseaton]

But why build the VM for every release then? What is it that needs to be cross compiled if you're just copying a VM build into a tarball? Why not copy an existing build of it in?

[gamache]

The VM is not built for every release, it is copied into the release. The fact that it isn't built for each release is why cross-compilation of releases is not possible.

[chrisseaton]

I must be an idiot because I still don't get it. If the VM is just copied into the release, not built, why can't you do that on macOS for deployment on Linux by copying a Linux version in? Why do you need to do it in a VM or Linux build server?

[gamache]

It's probably only that no one's written the tooling for that yet, because it's easy enough to set up a Linux VM or build server.

[kungfooguru]

The tools (relx, exrm) can do that.