Linus Torvalds suggests the 80486 architecture belongs in a museum, not the Linux kernel
- Reference: 1666680985
- News link: https://www.theregister.co.uk/2022/10/25/486_support_linux_kernel_ending/
- Source link:
The ancient architecture was up for discussion last week in a thread titled "multi-gen LRU: support page table walks" that considered how the kernel can better handle least-recently-used (LRU) lists – a means of tracking memory pages.
As Torvalds surveyed contributors' code, he appears to have been frustrated by the need to include workarounds that cater to older CPUs. He therefore [1]suggested ending support for old kit could be an easier way to solve memory matters.
[2]
"We got rid of i386 support back in 2012. Maybe it's time to get rid of i486 support in 2022?" he wrote.
[3]
[4]
Deeper into the thread, he [5]returned to the topic with the following observations:
So I *really* don't think i486 class hardware is relevant any more. Yes, I'm sure it exists (Maciej being an example), but from a kernel development standpoint I don't think they are really relevant. At some point, people have them as museum pieces. They might as well run museum kernels.
That position seems to be fueled by a little irritation, as even deeper in the thread Torvalds [6]commented "the kind of work needed to keep i486 alive is the kind of maintenance burden we simply shouldn't have – no developer actually cares (correctly), nobody really tests that situation (also correctly – it's old and irrelevant hardware), but it also means that code just randomly doesn't actually work."
He may well have a point: the i486 architecture debuted in 1989 and was succeeded by Intel's Pentium in 1993.
Intel washed its hands of the '486 in 2007 and today its famously detailed [7]Ark product database contains no mention of the processor family.
[8]
Anyone still running the devices has long since resigned themselves to doing so without support, the chance of acquiring new kit, or software developers giving the platform a second thought.
[9]Don't say Pentium or Celeron anymore, it's just Processor now, says Intel
[10]Linux Foundation celebrates 30 years of Torvalds' kernel with a dry T-shirt contest
[11]Linus Torvalds to kernel devs: Grow up and stop pulling all-nighters just before deadline
[12]Linus Torvalds's faulty memory (RAM, not wetware) slows kernel development
Yet The Register knows of one potentially very influential person who could conceivably weigh in to keep the venerable 80486 alive: Intel CEO Pat Gelsinger, who led development of the tech and has often said within your correspondent's earshot that he was told to make sure it excelled at running AI workloads.
At 100MHz, on a single core, with a 32-bit address space and a whole 16 kilobytes of cache.
Suffice to say the '486 is almost never mentioned when the history of AI is recounted.
And it appears the processor will also soon pass from Linux history to Linux legend. ®
Get our [13]Tech Resources
[1] https://lkml.iu.edu/hypermail/linux/kernel/2210.2/07782.html
[2] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/systems&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2Y1ezu3D09XyKltQMEN95jwAAAJA&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0
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[5] https://lkml.iu.edu/hypermail/linux/kernel/2210.2/08845.html
[6] https://lkml.iu.edu/hypermail/linux/kernel/2210.2/10853.html
[7] https://ark.intel.com/
[8] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_onprem/systems&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44Y1ezu3D09XyKltQMEN95jwAAAJA&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0
[9] https://www.theregister.com/2022/09/16/intel_pentium_celeron_processor/
[10] https://www.theregister.com/2021/07/08/linux_foundation_t_shirt/
[11] https://www.theregister.com/2022/10/17/linux_6_1_rc1/
[12] https://www.theregister.com/2022/10/10/linus_torvalds_ecc_memory_fail/
[13] https://whitepapers.theregister.com/
Re: Lessons?
They may have stopped supporting the i386 code in new kernels, but that doesn't mean i386 support has been removed from the old kernels ... some of which are still maintained. And of course all but a few of the very oldest kernels are archived for anybody to download and run whenever they feel the need. There will be no loss of hardware support.
This stuff isn't exactly written on papyrus and only known to the scribes and high priests.
"the kind of maintenance burden we simply shouldn't have"
If only he'd apply that philosophy to systemd and revert to init.
Re: "the kind of maintenance burden we simply shouldn't have"
"If only he'd apply that philosophy to systemd and revert to init."
This is not a kernel matter, but a distro matter.
Linus is not in charge of distros ...
But there's a 486 in the Hubble telescope.......
......I hope Hubble isn't running Linux!!
Re: But there's a 486 in the Hubble telescope.......
Planning on popping out there and updating the kernel were you?
Re: But there's a 486 in the Hubble telescope.......
It's not!
Generally agree, with Linus, but just last month we were commenting on features for the Atari Falcon being updated in kernel too. A very much more deceased platform!
I could be even more sinister and suggest stripping disused driver code too. Do you need really need that token ring ISA card in kernel?
On the dead hardware front I would not blink if anything up to and including the Pentium 4 and K7 ceased to be supported.
Generally agree, with Linus, but just last month we were commenting on features for the Atari Falcon being updated in kernel too. A very much more deceased platform!
68K didn't have a crazy architecture though and is still in use in embedded with ColdFire.
What you are missing is that all that old code is still going to be available. If you need a kernel for a mid 1990s HP server with Token Ring cards sometime 30 years from now, you'll be able to download it (both binary and source) from the archives. I'd recommend keeping it airgapped, but you should be able to recover any data from it and/or run an ancient program in situ should the need arise.
Linux 0.99pl12 will likely still be running on something, somewhere, until roughly the heat death of the Universe.
On the one hand, yeah, sure, who needs it, strip it out and be done with it.
On the other hand, this rather implies that support in the kernel for old processor architectures is on the critical execution path for current architectures, which rather makes me wonder if there isn't a fundamental design problem in there somewhere?
Me, I'd leave the code in, but make it a conditional compilation option, so that if you *really* want to run ancient hardware, you can, but the code isn't included on mainstream builds.
GJC
Re:
He does comment that it isn't tested. Doubtless that's why : it's there but almost nobody turns it on.
Re:
This is how our DNA got to be so big and complicated ….
Re:
As I understand it, it's not so much that the code as compiled that is the concern and more about the need to ensure that changes made and features added will work within the limitations of those older processors when writing that code in the first place (or include workarounds as noted in the article).
So it's more of a burden on developers than anything else
Genuine question...
...but isn't one of the benefits of Linux that you can use it on very old hardware? Would this stymie that?
Re: Genuine question...
You could still use it on old hardware, nobody is stopping anybody from using older kernel if they prefer.
Re: Genuine question...
Not only will you always be able to use older kernels, some of them are kept updated as needed. For example, LTS kernel 4.4 (released in very early 2016) will be maintained until at least 2026, and probably until 2036 ... and possibly beyond, if there is a need. There are other niche kernels that get backports for security issues and the like, and the folks who need them know where to look.
Re: Genuine question...
Yeah sure you can run linux on 486. You can get version 1.0 and some gcc version 2 and compile the whole thing. Isn't that the point of maintenance releases.
Or you could spend the resources to emulate the product. I don't understand why things like COBOL are still alive when as software is a "living" thing it tends to be updated to run with more modern features and languages. The problem is that people see it too much of risk to "maintain" something that is working and go for these new mega projects that end up in failure.
I love El Reg forums
Nowhere else would you get a downvote for asking an honest question.
Nowhere else would a downvote matter to anyone over 12 years old.
To me? Beyond perpetuating certain stereotypes within the Linux community, it's just funny.
To others? Dunno but it possibly puts them off asking questions.
As for your comment - ad hominid is all I'll say.
They are meaningless, but they are also used in childish attempts at bullying. That's why I generally don't see them.
That's "ad hominem", but I rather like your version. In this context it brings to mind monkeys flinging shit :-)
You do know that ad blockers work on more than just ads, right?
Heh, a blast from the past. I first installed Linux on my 33 MHz 486DX in 1991-1992 or so:
https://groups.google.com/g/comp.sys.mac.advocacy/c/7MdzcPwmPFs/m/r89Mb88DzsUJ
And you've only just recently got it running *just so*?
I'm sure many commentards have "just so" stories.
Nowt wrong w'that.
Lessons?
" And it appears the processor will also soon pass from Linux history to Linux legend."
The quote this is based on continues along the lines of "and some things, that should not have been forgotten, were forgotten" (lazy me does not look this up). I just hope it will not come back to haunt us, with this being a bit of an "unbidden oracle" quote.
I found it weird when they stopped supporting i386, I find it strange that now 486 is on the list, but it does make sense. The hardware is 30 years old, which is an eternity in this field. As much as I like to reminisce back to those simpler times (oooh, calculating the Vmode for the X conf? The hassle with DOS and the brain dead memory management, the twaeking of the autoexec.bat - ok, computers are easier to use now), I think our Emperor Penguin is right with that suggestion (not that I have anything to say in that discussion).