installing emsdk on Apple M1 hardware fails

[lpotter]

There is no precompiled emsdk package for Apple's new MacOSX hardware M1

lpotter@Lorns-Mac-mini emsdk % ./emsdk install latest
Error: No tool or SDK found by name 'sdk-releases-upstream-4764c5c323a474f7ba28ae991b0c9024fccca43c-64bit'.

and building emsdk fails:

./emsdk install sdk-upstream-master-64bit
...
Done installing tool 'llvm-git-master-64bit'.
Manifest error: No tool by name 'node-12.18.1-64bit' found! This may indicate an internal SDK error!
Traceback (most recent call last):
File "/Users/lpotter/emsdk/./emsdk.py", line 3082, in
sys.exit(main())
File "/Users/lpotter/emsdk/./emsdk.py", line 3062, in main
success = tool.install()
File "/Users/lpotter/emsdk/./emsdk.py", line 1840, in install
return self.install_sdk()
File "/Users/lpotter/emsdk/./emsdk.py", line 1851, in install_sdk
success = tool.install()
AttributeError: 'NoneType' object has no attribute 'install'

[sbc100]

emsdk only officially supports x86_64 today.

If you would like to try to add similar support for aarch64 macOS that be most welcome. The first level of support where we support building from source should be relatively straight forward and will probably just involve adding versions of node and python for aarch64 macOS. The second level of support where we supply pre-built binaries is likely to be a lot harder as it will involves CI builders to build and upload the packages. There is similar issue for adding support for aarch64 linux: #547.

Regardless, we should certainly be giving a better error message here.

There are two levels of support that we could add

[lpotter]

I could, but I would not know where to begin at add it. Perhaps someone could point me in the right direction, or even a similar git sha.

[sbc100]

BTW, in the mean time you should be able to build from source: https://emscripten.org/docs/building_from_source/index.html

Building from source will also allow you to find and fix any issues with llvm, binaryen and emscripten before dealing with emsdk integration issues.

[lpotter]

I thought using ./emsdk install sdk-upstream-master-64bit built from source?

This builds llvm, but seems to want to download node package.

[bobbydigitales]

Hey @lpotter, if all you want to do is run emscripten on an M1 mac then I just forced it to install the x86_64 version by changing line 112 of emsdk.py to 'machine = "x86_64'. This makes it grab the Intel build for mac which runs fine under Rosetta 2.

[lpotter]

Ok, that's one way to work around it, but it is not ideal in the long term.

[sbc100]

If you would like to work on a more long term solution (perhaps we could do it incrementally starting with pulling arm versions of python and node for example) I think we would need the help of one of you to write and test out a patch. I don't know of any other emscripten developers or users who have this hardware yet.

[bobbydigitales]

The Intel solution is working great for my needs and I don't see much need for a native ARM version. Maybe for now, M1 macs could be redirected to the Intel version with a small message. If that would be helpful, I might be able to write a patch for that so at least it works for now.

[sbc100]

That would be great. We could even link to this bug in case anyone wants to help work on it.

[lpotter]

I can certainly help, since i have hardware. Not sure I know emscripten or it's tools well enough to do the work myself, besides having my hands full with Qt WebAssembly.

[namniav]

In addition to @bobbydigitales's solution, I found that Emscripten can also be automatically installed with Homebrew running under Rosetta:arch -x86_64 brew install emscripten.
If you have no Rosetta installed yet:softwareupdate --install-rosetta.

[redblobgames]

Speaking of homebrew, I can't get openjdk working on arm, but I've tricked it into compiling emscripten for arm by symlinking to the intel/rosetta openjdk:

# install intel version of these dependencies, under rosetta
/usr/local/bin/brew install openjdk yuicompressor

# install arm version of these dependencies
/opt/homebrew/bin/brew install python@3.9 node cmake

# trickery: point to the intel versions of openjdk, yuicompressor
ln -snf /usr/local/opt/openjdk /opt/homebrew/opt/
ln -snf /usr/local/opt/yuicompressor /opt/homebrew/opt/

# install arm version of emscripten from source
/opt/homebrew/bin/brew install -s emscripten --ignore-dependencies

# trickery: point to the arm version of emscripten
ln -snf /opt/homebrew/opt/emscripten /usr/local/opt/

I can't say it's the right way to do it, but it does seem to work so far.

[sbc100]

java is no longer a hard requirement to run emscripten since the npm package of closure can also use the native and js versions.

[jerrans]

You can just patch the emsdk.py file to remove the checks for node and python tools, then install the arm64 versions them manually via brew. You can confirm the binary architecture using lipo:

jerrans-mbp-3:build-web schmidje$ lipo -info `which python3`
Non-fat file: /opt/homebrew/bin/python3 is architecture: arm64
jerrans-mbp-3:build-web schmidje$ lipo -info `which node`
Non-fat file: /opt/homebrew/bin/node is architecture: arm64

emsdk patch