what's with all the versions?

[eom]

I understand the need to recompile for different architectures (x86 vs arm / armv7 vs armv8), but why does this distro seem to release for specific devices? Browsing the Debian repositories, it looks like they have a single arm64 release that can run on any device that uses this architecture. What are the differences between the different releases per platform on Arch Arm?

The context here is that I am making a bootable usb and want to support as many architectures as possible. My preference is Arch linux, but it wouldn't be feasible to do an installation for each individual device.

[moonman]

ARM is not the same way as x86 where 1 kernel for the same architecture can boot up on almost any computer. It's headed that way for ARM, but still far from it as of now. Some devices need a specific kernel that was made for that particular device to support 100% of the functionality of the device. The biggest problem is many different kinds of proprietary GPUs. So ArchLinux ARM provies these kernels for these devices so you will see many rootfs tarballs which come with device-specific kernels + other quirks required to get everything working.

Many of the devices have since been added to the mainline kernel and can boot up, but some are still missing certain pieces in the mainline kernel. A very good example is Odroid C1: the manufacturer's kernel is 3.10.x which supports all aspects of the kernel. Odroid C1 is somewhat supported in the mainline kernel, there are many things that don't work: eMMC, no video output (i.e. you can only access this device via SSH), lower performance, quirky USB (no hot plugging).

You can still get multi-platform tarball that comes with mainline kernel: https://archlinuxarm.org/about/downloads
Look for ARMv8 AArch64 Multi-platform or ARMv7 Multi-platform.

Debian or any other distro are exactly the same in this sense, although debian does not support non-mainlined devices officially, as far as I know. That's why there are/were projects like Rasbian and Armbian