Toward JavaScript on genode using Moddable XS

Video companion:

1. JavaScript on the Genode Microkernel OS, part 1: hello genode - Twitch

It works like this, once it's built (see below):

goa-hello$ goa run
[goa-hello:make] recursive make: make
Genode 20.02-1-gac1b2ec24e
17592186044415 MiB RAM and 8997 caps assigned to init
[init -> goa-hello] Hello before libc
[init -> goa-hello] hello via stdio
[init -> goa-hello] Hello in libc
[init -> goa-hello] lin_xs_cli: loading top-level main.js
[init -> goa-hello]  lin_xs_cli: loaded
[init -> goa-hello] lin_xs_cli: invoking main(argv)
[init -> goa-hello] Hello, world - sample
[init -> goa-hello] main() returned immediate value (not a promise). exiting
[init -> goa-hello] Warning: rtc not configured, returning 0
Warning: blocking canceled in entrypoint constructor
[init] child "goa-hello" exited with exit value 0

I started with the hello package from then Nov 2019 article introducing goa.

Then I grabbed the helloworld example from the Moddable XS SDK, generated C sources, and got it to build.

Then I worked out getting goa run to work. My artifacts is a bit of a kludge: it reaches out from var/build back to src/bin.

before goa build: gensrc, genode_platform

There's a bit of an impedence mismatch between goa build and the Moddable SDK, so use make -C src gensrc to generate C etc. before running goa build.

We also extend the Moddable SDK to add a genode platform using make -C src genode_platform.

Respin workflow

The several layers of build directories and makefiles means the dependencies are easy to get out of date, so the respin target does realclean before the rest:

make -C src respin && goa build

or for debugging:

make -C src respin && goa build --verbose --jobs 1

Next Steps

• event loop: Figure out how to integrate the port of glib to genode to turn the event loop, which is currently commented out, back on.

• nix and dhall: Compare goa to genodepkgs