Linux Kernel Developers consider dropping RiscPC support

Linux Kernel Developers are considering dropping support for many old ARM systems including the Acorn RiscPC and similar. See article on Phoronix and the linked mailing list post.

Yeah, stupid idea saying “oh, no new commits so let’s kill it”.
One might otherwise interpret “no new commits” as meaning that the platform has reached stable maturity (and that everything else is doing it wrong).

After all, while one may build various incarnations of the Linux kernel, the actual system specific parts really shouldn’t be changing that much, if at all, on a system that is well supported, well documented, and not prone to changing. The RiscPC has been the same for the past quarter century, so to be honest I would find it worrying if the underlying platform specific code was having changes committed…

The RiscPC has been the same for the past quarter century, so to be honest I would find it worrying if the underlying platform specific code was having changes committed…

In that time Flash came and went and never really got stable

Ah, but Flash has always been a moving target hacked together by…oooh shiny!

Not the most accurate description here. The exact quotes with relevance to the RiscPC are :

Then there are ARM platforms that are old but have still seen some work in the past years. If I hear nothing, these will all stay, but if maintainers may want to drop them anyway, I can help with that:

* rpc — prehistoric, but I think Russell still uses his machine

ie they aren’t immediately proposing to kill it, unless Russell King decides he really wants to stop supporting it. And further comments in the mailing list thread suggest that he doesn’t want to stop supporting it, so RiscPC support in the kernel isn’t going anywhere, at least for a while.

Also, Rick’s comments on “no new commits” – if the platform hasn’t received any commits for several years then it’s highly likely it hasn’t kept up with changes in the kernel, and is most likely broken. There’s no advantage to the Linux kernel to be carrying around broken code for platforms that no one is interested in maintaining; just delete it and make it clear that it isn’t supported anymore.

What is the version of the kernel used in Risc PC Linux? I last played with it at around 2.1, and I wouldn’t be surprised if it was still there, the Risc PC ran Linux pretty terribly. The Iyonix should have been slightly better, but I never got around to trying it, particularly as a Pi 1 would out perform it.

Given that mainline is still receiving mach-rpc patches (most recent was on the 30th of October), you should be able to build a working RiscPC kernel from that, so 5.11-rc3 should work.

then it’s highly likely it hasn’t kept up with changes in the kernel, and is most likely broken.

Now, I shall begin by saying that I know nothing about how Linux is put together, however given that it is available on many different devices, it would make sense if the core kernel code is abstracted from the platform specific low level guff (bringing the hardware up, responding to processor exceptions, and so on). Build it for the Pi, plug in the ARM bcm2xxx code. Build it for your IPcam, plug in the MIPS RTL8xxx code. The kernel is the same. The platform glue differs.

This is then supported by various device drivers. The IOMD mouse, the VIDC, a serial port, blah blah blah.

Now, unless the kernel does something weird like completely changing the ABI, then I’m afraid that I’d have to raise an eyebrow if the hardware glue code or device drivers need to be rewritten or patched because the kernel changes. That platform specific stuff for a mature non-changing piece of hardware should have become stable at least a decade ago (if not longer).

Nope! This ain’t RISC OS, Linux kernel code and internal interfaces change over time. If no one is maintaining the individual platforms then they become dead broken code, and dead broken unmaintained code isn’t useful to anyone.

Have a look at the changelog for the mach-rpc directory : https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/arch/arm/mach-rpc?h=v5.11-rc3

Most of them are updates and fixes due to changes in other parts of the kernel, including changing internal APIs over time.