Use ARM runners for CPython and Numpy

[AutonomicPerfectionist]

This PR enables ARM builds for CPython and Numpy by using the Github Actions ARM runners. It also makes minor changes to the cppbuild.sh scripts for both to fix compilation issues on ARM. For numpy, this entailed removing the workaround implemented in #1386.

Note

I made the minimal changes necessary to fix ARM compilation. This means that the cpython build still essentially does cross-compilation to target ARM even when running on ARM hosts. It may be desirable to add a check for whether the target and host platforms match to improve build times.

The cpp build was verified to succeed on a Raspberry Pi 4, I have not yet verified full end-to-end success via maven due to a missing dependency on the pi.

[saudet]

Sounds good, but why are the CI actions not running? 🤔

[saudet]

Ok, the formatting of the workflows was incorrect. Now it still fails, so anyway please fix it!

[AutonomicPerfectionist]

The numpy workflow seems to have failed because the ubuntu image has the wrong sources.list for apt, ARM64 packages are hosted at http://ports.ubuntu.com/ubuntu-ports, not http://archive.ubuntu.com/ubuntu. The cpython workflow is just showing me an fallocate error, which shouldn't have anything to do with us and is probably a transient error.

[AutonomicPerfectionist]

It seems the github action tries to workaround an Actions issue by selecting a mirror, but the mirror selected is the archive.ubuntu.com one and not the ports.ubuntu.com:

Mirror: http://archive.ubuntu.com/ubuntu/ - UP
The closest mirror is: http://archive.ubuntu.com/ubuntu/
Updating /etc/apt/sources.list
Updated '/etc/apt/sources.list' with http://archive.ubuntu.com/ubuntu/

[AutonomicPerfectionist]

Appears to be a problem with apt-spy2, the lines in the action that appear to select a mirror use it:

javacpp-presets/.github/actions/deploy-ubuntu/action.yml

Lines 84 to 85 in 754110d

	$SUDO apt-spy2 check
	$SUDO apt-spy2 fix --commit

[saudet]

Ok, so could you try to fix it?

[saudet]

If I remember correctly, the checks for "amd64" is to detect cross compilation, so we should be able to skip all that when running actually running on ARM...

[AutonomicPerfectionist]

I've attempted a fix by simply disabling mirror selection for arm64 runners

[AutonomicPerfectionist]

Hmm, both runs failed again, with an error on fallocate... I do see that the fallocate command is being used to create a 4GB swap file, but I can't imagine the arm64 runners would be so resource constrained that they can't allocate an additional 4GB on the filesystem...

javacpp-presets/.github/actions/deploy-ubuntu/action.yml

Line 24 in 754110d

$SUDO fallocate -l 4GB /swapfile

I've pushed a new commit that just disables the fallocate call, but it didn't seem to change anything. I'll revert that commit and continue looking for the cause of the error

[saudet]

To test the actions, you'll need to change temporarily the workflows to point to your branch

[saudet]

We need this when cross compiling though. Please disable it only when we're running on ARM

[AutonomicPerfectionist]

Will do

[AutonomicPerfectionist]

To test the actions, you'll need to change temporarily the workflows to point to your branch

Yeah I figured that out, been playing whackamole with some more issues on a different branch of mine. Slowly getting there