No Stupid Questions

Windows is designed to work on a very wide range of specs, so older devices as well as low-end newer devices should be able to run it.

That’s even more true about Linux. Many popular distros can be run on a raspberry pi, a 20 year old MacBook, or a state-of-the-art gaming desktop.

It’s less true about macOS because Apple has more control over the hardware so they can be pickier. Mobile developers also have more control over the hardware and can be pickier, although that’s less true about Android than iPhone.

in the case of Android, it comes down to the proprietary driver modules that are compiled for certain kernel versions. As newer versions of android are released with newer kernels, the closed source modules fall out of step. If the drivers for these components were open source anyone could recompile them for any Linux kernel. It's usually up to the device manufacturer working with the likes of the chip makers to release newer module versions for their hardware. OEMs dont want to support their hardware beyond few years, so you'll hopefully buy a new phone.

The postmarketOS community (and some of the android community) works pretty hard trying to bring mainline kernel support to devices, which enables them to run generic Linux kernels, or conceivably newer versions of android than the OEM has released. But this involves reverse engineering support for this hardware.

Simple. We let them get away with it. Compare:

"Your PC is out of date" "Don't be stupid, it's only 2 years old and still works fine" with

"Your phone is out of date" "OK I'll buy a new one".

There needs to be a lot more of Answer A to Statement B.

On Mobile OS updates are tied to firmware updates while on PC they're completely seperate. Its also a severe issue on Arm based Linux PCs, if they loose support or worse never had Linux support they can be nearly impossible to use.

Computers have systems (BIOS, EFI, ACPI) that give the people who make the machine responsibility for providing a standard, publicly-defined way for the OS to enumerate the hardware, and to use the hardware in a basic way even if the OS has never heard of it. Linux can get a kernel panic on the screen even if it has no idea what your GPU is, because EFI understands it and Linux understands EFI. It is set up this way partly because there's a real possibility of hardware being added or removed, partly because people routinely mix and match parts, and partly because IBM mistakenly designed a good system that was easy to work in and not one that kept them in business.

Phones (and phone-derived systems like the Raspberry Pi and other single-board computers) don't implement a standard. The hardware and its boot process assumes tight integration between the hardware and the software, usually to the point where the bootloader refuses to load anything not signed by the device manufacturer, unless it is satisfied that it has been given that manufacturer's permission to be unlocked. (Computer secure boot implementations generally trust, for example, Microsoft, as well as the machine owner, who can load their own keys.)

Instead of the CPU developers releasing example EFI implementations, they release forks of the Linux kernel that they maintain as long as that chip is the latest chip they sell, and then fork off the mainline kernel again for their next chip. And the device makers ship devices by starting with the chip maker's kernel, customizing it for the device, giving it a "device tree" that tells it everything that is supposed to be in that particular device, and shipping it. For a few years they port patches from the current kernel onto this forked kernel, and then they stop. With no standard to develop software against, and no documentation for what's in a device and how to use it like there is for the standard's interfaces, the only practical way to run software on a device is to start with that patched kernel.

Mainline Linux refuses to adopt and maintain the chip and device makers' low-quality, chip-and-board-specific kernel changes (often because they break the kernel for other uses), so you can't generally use a mainline Linux kernel instead. If you tried to tease out and improve the device-specific patches to the point where mainline Linux would take them, the device would be hopelessly outdated by the time you were done and you would have dozens of job offers to occupy your time as a highly skilled embedded Linux developer. The work is not practical given the tiny number of people who would benefit from it for a particular device, and how little it pays off compared to just buying a new device with a more up to date forked kernel available.

"Maintaining" a device for LineageOS or other open software eventually collapses under the weight of mainline Linux's changes and the necessary chip and device maker patches no longer being practically reconcileable.

This is changing. Microsoft is trying to restrict Windows 10 -> uploads based on having a user-hostile TPM module to make PCs more locked down, just like phones.

https://usilenie-plus.translate.goog/2016/google-plz/?_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en-US&_x_tr_pto=wapp

PC operating systems are, at least to a broad degree, generic. That's because a huge amount of backwards compatibility is built right into the PC architecture, much to the delight or chagrin of everybody depending on who you ask. There's silicon on your processor's die right now that's doing fuck-all except ensuring that if you were struck by the perverse urge, you could boot MS-DOS 1.0 onto it even though it's virtually guaranteed that you never will.

Phone operating systems absolutely are not generic, because each phone model is basically unique unto itself in terms of what hardware is in it, and backwards compatibility is not in any way a design goal. Furthermore, the entire package has to be rolled into a single unified ROM image.

There are proprietary core components in phones, notably their SoCs (systems-on-a-chip) and modems (which are often built into the SoC) which their designers jealously guard and are loaded down with patents and other IP restrictions. This hardware requires closed source drivers which must be updated or at the very least recompiled for new kernel versions if the OS is to be updated. That's for Android, anyhow. It's even worse for Apple devices, because they're entirely closed and Apple is in total control of both the hardware and the software. At least they bother to support their own devices with updates for quite some time, but even they're not absolved of fuckery -- see, for instance, the deliberate slowing-down-with-updates scandal from a few years ago.

If nobody is providing source code or compatible binaries for the core hardware your phone needs in order to work, at minimum it's going to be impossible to update your device beyond the kernel version that was last supported on it, even with a custom ROM. And all of this is before getting into locked bootloaders and other chicanery that prevents you from running your own code outside of user space on the hardware even if you had the code to run.

At the end of the day: The hardware vendors are absolutely not interested in providing driver support to end users or source code to anyone, and the handset makers and most especially the cell service carriers, at least in the US where the majority of people buy or lease their phones from said carriers, literally have a vested interest in dropping support as soon as they can get away with it. That's because rolling out updates to oodles of individual phone models costs money to do, but they only make more money off of you by selling you a new phone.

Because they are incentivizing us to buy new phones. It's not a technical reason it's a capitalism reason.

Part of this is because the device has to connect to cellphone towers where the radio equipment is on its own lifecycle path and eventually replaced.

Eventually the feature set of a device is too outdated for the carrier's network to syooort it.

Developer time is limited and so there is little to no value using that time to support very old hardware that would be WiFi only.

Operating systems for computers are generic, operating systems for phones are specific

This is the crux of the problem, there is no single repository where a mobile operating system has been made to generically work anywhere

Planned obsolescence to a degree. If you spend $1k a year on a new phone the C suite makes happy faces, but of you spend $1k every few years the C suite makes sad faces. What better way to keep them happy by stopping support for a device.

Even for Linux there is a end of life for devices: https://linuxiac.com/linux-kernel-to-drop-support-for-legacy-i486-and-early-586-cpus/

The difference to phones is that around Linux everything is open source so that some poor shmuck ho still has this old computer and is capable can keep supporting it for everyone. When it comes to phones it's much more difficult because a lot of the parts are closed source. Similarly to Mac OS and Windows.

PC = General Purpose
Mobile devices = Purpose built

PCs are generally based around the X86 chip architecture which is an open standard. PCs are basically modular and lots of manufacturers make components that are interchangeable, creating a huge variety of possible hardware. Hardware suppliers also sell to both big manufacturing companies and individuals. It's therefore in their interest to distribute their drivers freely even if closed source. If hardware breaks it can be replaced and the PC keeps going, and some components can be kept going for years as a result as people dot have to throw the whole machine out everything something breaks or becomes obsolete.

Mobile devices are closed standards. They use a more limited range of off the shelf components which are deeply integrated into a device, and the hardware suppliers provide their drivers to the device manufacturer or the device manufacturer builds their own drivers and custom version of the os. Hardware can have very long retail lives selling for years and still being functional, so the manufacturers have an incentive to keep drivers available and even update them.

It means mobile devices are more locked down, and the hardware drivers harder to come by. This makes it hard to build custom OS for them and therefore when the device comes to the end of its support from the maker there is limited options to keep it running securely.

It's effectively a type of planned obscelence that keeps the mobile industry going. Manufacturers stop supporting old devices (because it provides no income) and then consumers have to buy new ones as no one can provide the security patches to keep them secure.

So for mobile there is nothing to force Android or IOS to be kept up to date for old devices. The money is in new devices, and for Android manufacturers are responsible for the mobile device anyway. While for PC it's in Microsofts interests to keep updating and keeping devices secure via Windows becuase devices have long lifespans and old components can be in the PC ecosystem for decades. Similarly Linux is able to support hardware for a long time because drivers are more freely available and long lifespans to hardware incentivise people to put the effort in to write open drivers when they're not there.

Microsoft is trying to force an upgrade cycle at the moment with Win 11 though. And the laptop industry ia more like the mobile industry than the desktop pc industry with more propriety devices and locked down hardware.

Corporate greed.

x86 hardware interfaces are traditionally pretty well documented and standardized, going back to the original IBM PC in the 1970s(?), enabling among other things an aftermarket of plug-in expansion cards and other peripherals. That standardization also makes it possible to write device drivers and keep them working.

ARM stuff on the other hand is closed and changes all the time. So this year's peripheral won't work with last year's phone. Mac stuff is also like that, maybe not quite as much most of the time.