[CentOS] What about the AltArch repositories? (+ some experiments with aarch64 on Raspberry Pi)

I asked about this before.  As far as CentOS itself is concerned this
is an unknown.  For me it's kind of annoying because I just set up a
couple of Raspi 4's with CentOS 8 for a home automation system right
before this announcement was made.

Having said that- there is a little known distro called "RedSleeve
Linux".  It's just a couple of guys who do builds of RHEL 6, 7, 8
specifically for ARM systems.  I contacted those guys because I did
some work with them in the past, and I suggested they work with the
folks at RockyLinux to combine efforts.

On Wed, Dec 16, 2020 at 3:51 AM Mathieu Baudier <mbaudier at argeo.org> wrote:
>
> Hello,
>
> given the recent change in direction of CentOS, what will become of the
> AltArch repositories? (like CentOS 7 aarch64 and the related kernel
> repositories)
>
> I have been experimenting (with some success) with running a regular CentOS
> 8 aarch64 (ARM 64 bits) on a Raspberry PI 4 (with 4GB RAM), using the
> aarch64 kernel-rpi2 provided by CentOS 7 AltArch [1]. (a few more technical
> details below)
>
> This is a very different question than what is currently hotly discussed on
> this list, with the end of the bug-for-bug clone of RHEL, as there were
> never expectations that such settings would be supported. But on the other
> hand, I liked to use CentOS for innovation in a given field (mostly Java
> related) as its stability allowed one to go deep into one direction with
> "other things being equal" (contrary to Fedora, which is always moving in
> all directions).
>
> I guess that all these "side projects" (and SIGs, etc.) will disappear as
> well, won't they?
>
> Cheers,
>
> Mathieu
>
> ## More details about running CentOS aarch64 on a Raspberry Pi 4
>
> As for my experiments with running CentOS 8 on a Raspberry Pi 4, a bit more
> details, so that these efforts are not completely lost. Two approaches were
> working :
>
> - From a plain CentOS 7 AltArch aarch64 installation, perform a CentOS 8
> aarch64 install in a chroot (with the --installroot option) + a clean
> kernel-pi2 install from the CentOS 7 kernel-pi2 repository. Then copy the
> chroot to an .img file, and use this image to initialise an SD card.
>
> - From a plain CentOS 7 AltArch aarch64 installation, perform an in-place
> upgrade to CentOS 8 (first install dnf from EPEL, then switch the repos,
> and it works)
>
> The second approach had better device support on the Raspberry Pi 4 (most
> importantly the wifi, which was not working with the first approach), but
> this was probably a matter of subtle kernel / modprobe configs that were
> beyond my skills. I thought that I would share all this at some point, and
> ask for help from the CentOS AltArch developers; but I guess it is
> irrelevant right now.
>
> Both approaches were working equally well on the Raspberry Pi 3 (but Fedora
> support is good for this version, while Raspberry Pi 4 is not supported, so
> I tend to use Fedora aarch64 on them).
>
> As for what is actually the point of doing all this, this is not for
> weekend hobby tinkering, and it is relevant for server-side applications.
> ARM 64 bits is becoming an important platform (hence the fact that RHEL is
> now supporting it, MacOS will soon completely move to it, etc.) especially
> if one is interested in climate-friendly low-power IT, also on the
> server-side. But finding hardware is not easy and the (cheap) Raspberry Pi
> have 64-bit capable processors, even though the default distrib (Raspbian,
> based on Debian) does not yet support 64 bits (but they are working on it
> [2]). After trying many distributions, a paradox was that CentOS was
> actually the easiest to deploy and use in order to get some results (thanks
> to the work of the AltArch team!)
>
> In my case, the main interest was to test on ARM 64 bits GraalVM, the next
> generation Java platform, which can compile Java (and other programming
> languages) to native code. These builds require a lot of memory, but with
> an extremely slimmed down CentOS 8 and the 4 GB memory of the Raspberry Pi
> 4, it worked! [3]
>
> On a different layer, I could also test Eclipse SWT (Java user interface
> library) on this architecture (but on the plain CentOS 7 aarch64 with
> GNOME), and provide some quick feedback to Eclipse developers on their
> recent support for the whole Eclipse IDE on ARM 64 bits. [4]
>
> [1] http://mirror.centos.org/altarch/7/kernel/aarch64/kernel-rpi2
> [2] https://downloads.raspberrypi.org/raspios_arm64/images/
> [3] https://twitter.com/mbaudier/status/1274263320254722050
> [4] https://twitter.com/mbaudier/status/1291421892381937670
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