Is it possible to predownload ports in emsdk docker?

[ericoporto]

I am trying to make an emscripten dockerfile, I am going to cache this docker image and run the builds on this docker image.

I want to also pre-download the Emscripten ports.

Is there any command line command that can do this? My docker image uses emsdk from here (FROM emscripten/emsdk:3.1.2): https://hub.docker.com/r/emscripten/emsdk

[kleisauke]

I think you can extend the existing Docker image and run embuilder.py build USER to download (and build) all ports. For example:

FROM emscripten/emsdk:3.1.3

RUN embuilder.py build USER

$ docker build -t emscripten-ports . 

(note that this currently fails for zlib due to #16164)

[kleisauke]

Issuing embuilder.py build USER causes every port to be built. embuilder.py accepts multiple arguments, so you can just do embuilder.py build freetype harfbuzz (for example).

[ericoporto]

thanks, did just that and it worked! 😄

[ericoporto]

(hey, is it possible to pre-generate libc so I can skip generating system library: sysroot/lib/wasm32-emscripten/thinlto/libc.a. ?)

[ericoporto]

The specific problem being the flag to force thinlto

from embuilder:

  if args.lto:
    settings.LTO = "full"

I don't need full...

[kleisauke]

For regular/full LTO, you could use embuilder.py build libc --lto. For thin LTO (which is not heavily tested), there isn't such argument. Perhaps we should extend the --lto setting of embuilder.py by accepting value arguments (e.g., --lto=thin), just like emcc.

emscripten/emcc.py

Lines 2996 to 3000 in e415e01

	elif arg.startswith('-flto'):
	if '=' in arg:
	settings.LTO = arg.split('=')[1]
	else:
	settings.LTO = "full"

emscripten/embuilder.py

Lines 153 to 154 in e415e01

	if args.lto:
	settings.LTO = "full"

(Or allowing something like EMCC_CFLAGS="-flto=thin" embuilder.py build libc)