Linux 6.13 To Drop Fieldbus Just Five Years After Being Merged

[DavidBrown]

Presumably it is being done where it should be, as a user space program or library.

I'm really not sure why everything now needs to be done in the Kernel. We've got web servers, display managers, SMB/NFS network connections all in Kernel... It's starting to look like 1990s Windows....

As far as I can tell, the "fieldbus" stuff in the kernel was an attempt to get generic support for many types of industrial communication in place, along with driver support for a specific interface card. This might have been a good idea if it was followed up by adding more such support, but that never materialised. So the fieldbus code would only have been used by a few people with that specific (outdated, I believe) interface card.

There were actually valid reasons for trying to put some of this kind of stuff in the kernel. In particular, some industrial communication is high speed and requires low latency and deterministic timing - polls or updates that run hundreds of times a second with a 1 millisecond timing margin have traditionally been very hard to achieve in user space. But that is changing now with real-time Linux becoming better integrated, along with multiple core processors even on small embedded systems (a rarity just five years ago). In addition, it used to be common for interfaces for specialised industrial protocols to be in the form of add-in cards for PCI buses, ISA buses (remember that? It lasted far longer in the industrial world than the normal PC world) and others. For such cards, a kernel driver is almost a necessity. Now, these are all connected by USB if they are not handled by normal Ethernet interfaces. And USB (and Ethernet) can be handled efficiently from user space.

[DavidBrown]

I would it would have reduced to two questions:

1. is Fieldbus actually used today anywhere?

If not - who then really cares if it is removed?
If yes then

Industrial "fieldbuses" in general are used everywhere in factory automation. Pretty much anywhere that you have two or more "machines" with a common controller, there will be a fieldbus involved.

That does not mean that the particular flavour of "fieldbus" in the kernel is found everywhere, and certainly does not mean that the interface card supported by the driver is common. I've only looked a little at the code in question, but it appears to be for a high speed RS-485 based protocol. Such protocols are rare in modern installations, but still very common in old installations.

2. Is the Linux implementation of the Fieldbus spec actually used today?

if not - not much point again - sort of like the Bible translated into Klingon.
if yes - then why isn't one the users of this code stepping up to act as maintainer?

I would be very surprised if the fieldbus stuff in the Linux kernel is in significant usage today. Industrial communication is done from userspace, or using more specialised hardware (like PLCs), or on Windows systems. (Windows is an insane choice of OS for critical systems that you will want to keep running for decades, but that's the way it is.)

The people who make systems using fieldbuses are automation engineers - they have no knowledge or interest in the Linux kernel, and are usually blissfully ignorant of whether the PLC they are programming runs Linux, embedded Windows, or a proprietary OS. Companies making PLCs or hardware interfaces might have something to gain, but they are mostly too competitive to share with others.

[sophisticles]

It certainly doesn't run on winblows, macose or bsd. So yeah, when comes to general purpose OS'es the World runs on Linux.

I don't know what kind of drugs you are on, but you are wrong.

The PS3, PS4 and PS5 all run a BSD based OS, in the medical field where i worked desktop workstations were almost always Windows, with some Ubuntu thrown in, in the music, TV and movie industry I can tell you for a fact that most systems run either Windows or Mac OS.

My guess is that you are just a troll and not a very good one, so you just say stuff that you know is wrong to entertain yourself.

[mos87]

It took a single dumb post on the first page LOL.

Anyway there's a somewhat extensive discussion of what is Fieldbus in the previous topic on this issue.

[WileEPyote]

Seems like the Kernel is missing some maintainers, good thing they do all they can to keep every maintainer and not just exclude them because of current politics.

Oh, don't start this shit again. It happened. You can't change it. Deal with it.