On Mon, Aug 12, 2024 at 12:23 PM Matti Picus <matti.picus@gmail.com> wrote:
On 12/08/2024 11:55, slobodan.miletic--- via NumPy-Discussion wrote:

> As the bug fix is merged we are starting the investigation on the CI job.
> I have a few questions about this:
> 1) Are there some additional instructions for making and running the numpy CI jobs and cross compilation available in the documentation?
> 2) Do we need to have arm64 scipy-openblas released to build numpy wheel?
> _______________________________________________
> NumPy-Discussion mailing list -- numpy-discussion@python.org
> To unsubscribe send an email to numpy-discussion-leave@python.org
> https://mail.python.org/mailman3/lists/numpy-discussion.python.org/
> Member address: matti.picus@gmail.com


1. You can look at .github/workflows/linux_qemu.yml that use qemu/docker
to run.  AFAIK there is no documentation about cross-compilation.

There is: https://numpy.org/devdocs/building/cross_compilation.html

https://cibuildwheel.pypa.io/en/stable/faq/#windows-arm64 says that cibuildwheel only supports `setuptools` and `setuptools-rust` so far, so that's not particularly helpful yet. Neither is the `linux_qemu.yml` example I think, that's the furthest away from what we need I think (unless I missed something and QEMU or Docker actually supports Windows on Arm).

I'm not sure if this should go the `crossenv` way (see https://github.com/benfogle/crossenv), or a regular cross compile with a cross file and build/host envs. I think the latter won't quite work until PEP 739 (https://peps.python.org/pep-0739/) lands.


2. It would be preferable to build a scipy-openblas wheel but we could
use a "vanilla" build of OpenBLAS as well. We do expect to use 64-bit
interfaces, but scipy does not do so yet, so we would need two builds. I
don't know how @gholke compiles OpenBLAS/NumPy and where there is a
gfortran for windows arm64, maybe worthwhile asking?

I recommend getting step (1) to work first, without any BLAS library. That may be challenging enough - if there's a blocker, then there is no point looking into cross-compiling OpenBLAS before native arm64 CI runners become available.

Cheers,
Ralf


Matti

_______________________________________________
NumPy-Discussion mailing list -- numpy-discussion@python.org
To unsubscribe send an email to numpy-discussion-leave@python.org
https://mail.python.org/mailman3/lists/numpy-discussion.python.org/
Member address: ralf.gommers@gmail.com