Re: I run old hardware and am OK with it
> ... once you have a kernel that supports every bit of hardware on the system and is feature complete for your use, it's nice from an aesthetic standpoint to know you can potentially install newer kernels, but kind of irrelevant from a practical standpoint ...
This is not accurate most of the time. The overwhelming majority of a Linux "kernel" (i.e., kernel + device drivers + filesystems + IPC support + networking stack + ...) is not the CPU-specific support code. As you'd expect, the overwhelming majority of the bugs are also not in the CPU-specific support code but in the other stuff, and fixing most of them doesn't require changes to CPU-specific support code. This is very likely why there has been little change to the CPU-specific support code for these CPUs: the code that's there works fine and as there aren't any new CPUs being made, there's no need for additions.
But one should not conclude that there's no value in a newer OS on those CPUs. Unless the platform is so minimal that there's absolutely nothing but, say, the CPU core and a single embedded UART or I2C interface in use, it's very likely that the older Linux contains bugs in generic code that's being used on the platform. Whether this is so is of course a question specific to a given platform and the Linux configuration that ships with or is normally used with it, but if the embedded system utilises e.g. IPv4, it's practically certain. All such platforms obtain value from being able to run newer Linuxes, regardless of whether any of the CPU-specific support code changes or needs to change.
There are reasons to cut off support for old hardware, but "the code to support it hasn't changed in a while" is not among them, and the assertion that those platforms can't benefit from newer generic software is almost always wrong. The proper reasons to end support include:
- There are no functioning examples of the hardware in real use. This is a bit weaker than "none exist and are available for testing": if no one wants to use the hardware in anger, the fact that someone somewhere is "willing to test" is irrelevant. In that instance, those users are free to maintain museum forks if desired, but there is no point in maintaining support for something that is of only historical interest. Museum hardware can just as well run museum software. This is about the use of the hardware, not its age: there are models 30 years old that are still in active scientific or revenue use, and there are models only 10 years old of which no examples are ever powered except as curiosities.
- Maintaining the hardware-specific software has become a burden on people working in generic software. Usually this indicates that one or more parts of the system were poorly architected to begin with, but if the hardware itself is also obsolete there may not be anyone willing and able to rewrite the software in a way that allows generic development to proceed.
- The hardware lacks some capability that blocks the development of important general-purpose features. This is unlikely to apply in Linux, where the concept of universal features has never really existed and the idea of true cross-platform functionality is considered largely unimportant.
Assumptions about needing newer and necessarily fatter userland software are largely orthogonal and often wrong. If someone is using the platform in anger and has ample incentive to continue doing so, suitable solutions will be found -- as you have done yourself.