ARM builds?

[takluyver]

This is a very speculative issue. I'm aware that PEP 513 says manylinux1 is only defined for i686 and x86_64. But it would be nice if instructions telling people to pip install compiled modules worked easily and quickly on things like the Raspberry Pi too. It might also be valuable to the few brave souls trying to make Python work on mobile platforms.

So this issue is a place to work out what would be needed.

1. Architecture requirements: there are a lot of different versions of ARM, and there are confusingly similar looking version schemes for the architectures (e.g. ARMv7) and cores (e.g. ARM11). There may also be optional modules. Debian supports three buckets of ARM architectures: armhf requires ARMv7 and a floating point unit (hf = hardware float). armel supports older architectures, and cores without an FPU. arm64 is for the newer 64-bit processors. In terms of raspis:

• Raspi 0 and 1 have ARMv6 architecture, so Debian armhf does not support them. They do have FPUs, though, so Raspian is compiled to make use of this.
• Raspi 2 has ARMv7
• Raspi 3 has a 64-bit ARMv8 architecture.

2. Minimum library versions: These probably don't need to be all that old, because the systems I think this would target are likely to be running a relatively recent distro. But we'd need to work out what they are.

3. Distro for building: What distro would be the equivalent of the Centos 5.11 we use for building x86 and x64 manylinux wheels?

4. Build platform: Are there any CI services which offer ARM builds? Is virtualisation fast enough? Can we make it easy for people to build wheels on their own Raspberry Pi or similar device.

[rmcgibbo]

I am not personally very knowledgeable about ARM, so I don't know the direct answers to any of those questions. It would be really excellent if manylinux could support ARM at some point in the future though -- I have the impression that it's a growing platform.

For the manylinux1 spec, @njsmith and I leveraged a lot of Continuum's work to define the base distro and minimum library versions. Since the manylinux1 release, Continuum has added some support for ARM to conda and their packages, so perhaps this would be a good place to begin to identify best practices.

[takluyver]

Thanks, that's good to know. It looks like they're targeting ARMv7 and using Raspbian to run the builds.

[njsmith]

Unless someone wants to do lots of abi compatibility testing across different arm distributions, I think the most viable way forward here would be to push forward with the idea of distro-specific wheel tags, so that people could upload e.g "raspbian wheels"?

…

On Dec 12, 2016 3:40 AM, "Thomas Kluyver" ***@***.***> wrote: Thanks, that's good to know. It looks like they're targeting ARMv7 and using Raspbian to run the builds. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#84 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAlOaLss6R_-ibhkVU8Q45O-oTuK5bUhks5rHTKugaJpZM4LJ_pp> .

[KellenSunderland]

Using dockcross works quite well for ARM builds. I've created a few packages that use cross-compilation rather than virtualization. Builds that take hours on a Pi typically take a minute or two. This Dockerfile for example builds packages that run well for me with a Pi3 + Raspbian jessi. https://github.com/dockcross/dockcross/blob/master/linux-armv7/Dockerfile

[takluyver]

Since my motivation for this was getting Python packages on a Raspberry Pi, I'll drop a link to piwheels, @bennuttall's project to compile wheels for that platform.

[bennuttall]

An overview:

Although the hardware spec of Pi 1/Zero is ARMv6, Pi 2 is ARMv7 and Pi 3 is ARMv8, the reality is that Raspbian runs in ARMv6 user space regardless on your hardware. When you build a wheel on a Pi it's tagged armv6l on Pi 1/Zero and armv7l on Pi 2/3, but really it's always ARMv6.

So my project piwheels provides wheels for Raspberry Pi, but I wouldn't bank on the platform wheels working on other ARM boards. There's no particular need for maintainers to upload their wheels to PyPI as Pi users can use piwheels as their repo instead. Soon, in Raspbian, pip will be configured to use piwheels. (update: this is now true)

[QJKX]

Python on Termux (an android Linux environment) would also benefit from arm wheels.

[NotAFile]

We're having this problem with testing ARM in CI. The lack of wheels forces us to compile all dependencies for a fresh build, which takes around 20 minutes.

[vielmetti]

There is a CI system available, Drone Cloud, that can build natively for 32-bit and 64-bit Arm systems. There's also bare metal resources in the @WorksOnArm project to tackle this. Happy to help tackle this, especially for arm64 (aarch64).

[vielmetti]

@bennuttall - does piwheels support 32-bit Arm only, or do you also have 64-bit arm64 support?

[bennuttall]

We only provide wheels for 32-bit systems.