The future of 32-bit Linux

Only having kernel upgrades is not sufficient to keep an old system up to date. With newer kernels come new constraints and code sizes that are not always compatible with older hardware. I haven't tried booting 5.10 on my NSLU2 but I doubt it would be an option anymore. I barely managed to do it on a 9G20 board with 32MB RAM where I had to load it from the network to RAM because it wouldn't fit into the previous flash partition anymore.

The real problem with upgrades is connected systems. When you see a CNC device driven by an old 386 PC running MS-DOS 5.0 you smile and figure it was reliable and doesn't present any issue since that's not remotely accessible. It's the same for lots of deeply embedded Linux devices. The problem is that Linux is often used in networked environments and that it's so easy to connect it to a network that it's often done. And being exposed to the outside world *is* what requires security upgrades.

Thus we should admit that support for deeply buried systems can be dropped from newer kernels simply because these ones will not be updated and do not even need to. My point of view is that kernel support needs only to start from old devices that users want to repurpose. For sure I would be sad if I can't boot my old dockstar (ARM926) on a recent kernel. But let's be honest, the most recent version I've built for it was 3.7, 8 years ago. If 5.10 were to become the last one supported on it, it would apparently not be dramatic as I didn't feel the need for a more recent kernel on it for 8 years.