9 ms·

Removing nommu feels wrong to me. Being able to run linux on a simple enough hardware that anybody sufficiently motivated could write an emulator for, help us,

• reactordev 1y ago
  We need accessible open hardware. Not shoehorning proprietary hardware to make it work with generic standards they never actually followed. Open source is one thing, but open hardware - that’s what we really need. And not just a framework laptop or a system76 machine. I mean a standard 64-bit open source motherboard, peripherals, etc that aren’t locked down with binary blobs.
  • rwmj 1y ago
    Until we have affordable photolithography machines (which would be cool!), hardware is never really going to be open.
    • reactordev 1y ago
      The next 3D print revolution, photolithography your own chip wafers at home. Now that would be something! I doubt anyone here has a clean enough room.
      • jacquesm 1y ago
        Jeri Ellsworth has that covered. https://www.youtube.com/watch?v=PdcKwOo7dmM https://www.youtube.com/watch?v=PdcKwOo7dmM
        • reactordev 1y ago
          Insane… I thought I was smart, she proves me wrong.
          • jacquesm 1y ago
            Peter Norvig, Fabrice Bellard, etc. The list of ultra smart people is quite long. A friend of mine thought he was pretty smart (and I would have happily agreed with him). Then he went to work for Google (early days). It didn't take long for him to realize that the only reason he seemed very smart was that he simply wasn't seeing a large enough slice of humanity.
      • quantummagic 1y ago
        > I doubt anyone here has a clean enough room. Jordan Peterson has entered the building...
        • aspenmayer 1y ago
          Maybe if he cleaned his own room, he’d find his copy of the Communist Manifesto in time to read it for a scheduled debate. https://www.youtube.com/watch?v=qsHJ3LvUWTs https://www.youtube.com/watch?v=qsHJ3LvUWTs
        • lioeters 1y ago
          "Clean your rooms, men!" Starts sobbing
    • phkahler 1y ago
      >> Until we have affordable photolithography.... If that comes to pass we will want software that run on earlier nodes and 32bit hardware.
    • 15155 1y ago
      > affordable photolithography machines We'll likely never have "affordable" photolithography, but electron beam lithography will become obtainable in my lifetime (and already is, DIY, to some degree.)
      • NooneAtAll3 1y ago
        depends on what one means by affordable, but DIY versions have been successfully attempted https://www.youtube.com/watch?v=IS5ycm7VfXg https://www.youtube.com/watch?v=IS5ycm7VfXg
        • adrian_b 1y ago
          Making at home transistors, or even small-scale integrated circuits is not exceedingly difficult. However, making at home a useful microcontroller or FPGA would require not only an electron-beam lithography machine, but also a ion-implantation machine, a diffusion furnace, a plasma-etch machine, a sputtering machine and a lot of other chemical equipment and measurement instruments. All the equipment would have to be enclosed in a sealed room, with completely automated operation. A miniature mask-less single-wafer processing fab could be made at a cost several orders of magnitude less than a real semiconductor fab, but the cost would still be of many millions of $. With such a miniature fab, one might need a few weeks to produce a batch of IC's worth maybe $1000, so the cost of the equipment will never be recovered, which is why nobody does such a thing for commercial purposes. In order to have distributed semiconductor fabs serving small communities around them, instead of having only a couple of fabs for the entire planet, one would need a revolution in the fabrication of the semiconductor manufacturing equipment itself, like SpaceX has done for rockets. Only if the semiconductor manufacturing equipment would be the result of a completely automated mass production, which would reduce its cost by 2 or 3 orders of magnitude, affordable small-scale but state-of-the-art fabs would be possible. But such an evolution is contrary to everything that the big companies have done during the last 30 years, during which all smaller competitors have been eliminated, the production has become concentrated in quasi-monopolies and for the non-consumer products the companies now offer every year more and more expensive models, which are increasingly affordable only for other big companies and not for individuals or small businesses.
    • greesil 1y ago
      Why not run on an FPGA?
      • bigiain 1y ago
        That's being tried: https://www.crowdsupply.com/sutajio-kosagi/precursor https://www.crowdsupply.com/sutajio-kosagi/precursor "The principle of evidence-based trust was at work in our decision to implement Precursor’s brain as an SoC on an FPGA, which means you can compile your CPU from design source and verify for yourself that Precursor contains no hidden instructions or other backdoors. Accomplishing the equivalent level of inspection on a piece of hardwired silicon would be…a rather expensive proposition. Precursor’s mainboard was designed for easy inspection as well, and even its LCD and keyboard were chosen specifically because they facilitate verification of proper construction with minimal equipment." See also: https://betrusted.io https://betrusted.io
      • pjc50 1y ago
        This is somewhere in the 10x-100x more expensive and consumes much more power, for lower effective clock speeds. It's not a production solution.
      • mardifoufs 1y ago
        In addition to what the other comments have already highlighted, there's also the fact that you'd be back to using extremely opaque, even less "open source" hardware than regular CPUs/MCUs. Almost every FPGA that could even conceivably be used to run general purpose software is locked behind super proprietary stacks
    • Someone 1y ago
      https://en.wikipedia.org/wiki/Moore%27s_second_law https://en.wikipedia.org/wiki/Moore%27s_second_law: “Rock's law or Moore's second law, named for Arthur Rock or Gordon Moore, says that the cost of a semiconductor chip fabrication plant doubles every four years” Wafer machines from the 1970s could be fairly cheap today, if there were sufficient demand for chips from the 1970s (~1MHz, no power states, 16 bit if you’re lucky, etc), but that trend would have to stop and reverse significantly for affordable wafer factories for modern hardware to be a thing.
  • TheAmazingRace 1y ago
    We kinda have this with IBM POWER 9. Though that chip launched 8 years ago now, so I'm hoping IBM's next chip can also avoid any proprietary blobs.
    • reactordev 1y ago
      Indeed with the OpenPOWER foundation. Let’s hope some of that trickles down to consumer hardware.
      • stonogo 1y ago
        Unlikely: POWER10 required blobs, and there's no sign that'll change for Power 11.
        • deleted 1y ago
          [deleted]
  • AnthonyMouse 1y ago
    > I mean a standard 64-bit open source motherboard, peripherals, etc that aren’t locked down with binary blobs. The problem here is scale. Having fully-open hardware is neat, but then you end up with something like that Blackbird PowerPC thing which costs thousands of dollars to have the performance of a PC that costs hundreds of dollars. Which means that only purists buy it, which prevents economies of scale and prices out anyone who isn't rich. Whereas what you actually need is for people to be able to run open code on obtainium hardware. This is why Linux won and proprietary Unix lost in servers. That might be achievable at the low end with purpose-built open hardware, because then the hardware is simple and cheap and can reach scale because it's a good buy even for people who don't care if it's open or not. But for the mid-range and high end, what we probably need is a project to pick whichever chip is the most popular and spend the resources to reverse engineer it so we can run open code on the hardware which is already in everybody's hands. Which makes it easier to do it again, because the second time it's not reverse engineering every component of the device, it's noticing that v4 is just v3 with a minor update or the third most popular device shares 80% of its hardware with the most popular device so adding it is only 20% as much work as the first one. Which is how Linux did it on servers and desktops.
    • skeezyboy 1y ago
      > pick whichever chip is the most popular and spend the resources to reverse engineer it is this even doable?
      • FirmwareBurner 1y ago
        Doable yes. Economical no.
        • AnthonyMouse 1y ago
          It depends who you are and why you want it. Could Amazon or Facebook do this if they just wanted to, e.g. to help break the hold of their competitors on markets they care about? Absolutely. Could some hobbyist do it? Not on their own, but if you do part of it and someone else does part of it, the whole thing gets done. See e.g. Asahi Linux.
  • tonyhart7 1y ago
    I would love to works with hardware, if you can foot my bill then I be happy to do that since open source software is one thing but open source hardware need considerable investment that you cant ignore from the start. also this is what happen to prusa, everyone just take the design and outsource the manufacture to somewhere in china which is fine but if everybody doing that, there is no fund to develop next iteration of product (someone has to foot the bill) and there is not enough sadly, we live in reality after all
  • numpad0 1y ago
    Lots of SoCs are "open" in the sense that complete documentation including programming manuals are available. With couple man-centuries of developer time each, you could port Linux over those SoCs. but that doesn't count as being "open". On the other hand, there are a lot of straight up proprietary hardware that are considered "open", like Raspberry Pi. Which means, "open" has nothing to do with openness. What you want is standardization and commoditization. There are practically no x86 hardware that require model-specific custom images to boot. There are practically no non-x86 hardware that don't require model-specific custom images to boot. ARM made perceptible amount of efforts in that segment with Arm SystemReady Compliance Program, which absolutely nobody in any serious businesses cares about, and it only concern ARM machines even if it worked. IMO, one of problems in efforts going in from software side is over-bloated nature of desktop software stacks and bad experiences widely had with UEFI. They aren't going to upgrade RAM to adopt overbloated software that are bigger than the application itself just because that is the new standard.
  • bigiain 1y ago
    Bunny Huang has been doing a lot of work on this: Open hardware you can buy now: https://www.crowdsupply.com/sutajio-kosagi/precursor https://www.crowdsupply.com/sutajio-kosagi/precursor The open OS that runs on it: https://betrusted.io/xous-book/ https://betrusted.io/xous-book/ A secret/credential manager built on top of the open hardware and open software: https://betrusted.io https://betrusted.io His blog section about it: https://www.bunniestudios.com/blog/category/betrusted/precursor/ https://www.bunniestudios.com/blog/category/betrusted/precur... "The principle of evidence-based trust was at work in our decision to implement Precursor’s brain as an SoC on an FPGA, which means you can compile your CPU from design source and verify for yourself that Precursor contains no hidden instructions or other backdoors. Accomplishing the equivalent level of inspection on a piece of hardwired silicon would be…a rather expensive proposition. Precursor’s mainboard was designed for easy inspection as well, and even its LCD and keyboard were chosen specifically because they facilitate verification of proper construction with minimal equipment."
  • pjc50 1y ago
    > Open source is one thing, but open hardware - that’s what we really need This needs money. It is always going to have to pay the costs of being niche, lower performance, and cloneable, so someone has to persuade people to pay for that. Hardware is just fundamentally different. And that's before you get into IP licensing corner cases.
• eric__cartman 1y ago
  Those operating systems already exist. You can run NetBSD on pretty much anything (it currently supports machines with a Motorola 68k CPU for example). Granted many of those machines still have an MMU iirc but everything is still simple enough to be comprehend by a single person with some knowledge in systems programming.
  • kimixa 1y ago
    NetBSD doesn't support any devices without an mmu. I think people here are misunderstanding just how "weird" and hacky trying to run an OS like linux on those devices really is.
    • kbolino 1y ago
      Yeah, a lot of what defines "operating system" for us nowadays is downstream of having memory isolation. Not having an MMU puts you more into the territory of DOS than UNIX. There is FreeDOS but I'm pretty sure it's x86-only.
      • actionfromafar 1y ago
        Mmm... would beg to differ. I have ported stuff to NOMMU Linux and almost everything worked just as on a "real" Linux. Threads, processes (except only vfork, no fork), networking, priorities, you no name it. DOS gives you almost nothing. It has files. The one thing different to a regular Linux was that a crash of a program was not "drop into debugger" but "device reboots or halts". That part I don't miss at all.
        • kbolino 1y ago
          That's fair. If so, then you still can have things like drivers and HAL and so on too. However, there's no hard security barriers. How do multiple processes actually work, though? Is every executable position-independent? Does the kernel provide the base address(es) in register(s) as part of vfork? Do process heaps have to be constrained so they don't get interleaved?
• Blammmoklo 1y ago
  Supporting 32bit is not 'simple' and the difference between 32bit hardware and 64bit hardware is not big. The industry has a lot of experience doing so. In parallel, the old hardware is still supported, just not by the newest Linux Kernel. Which should be fine anyway because either you are not changing anything on that system anyway or you have your whole tool stack available to just patch it yourself. But the benefit would be a easier and smaller linux kernel which would probably benefit a lot more people. Also if our society is no longer able to produce chips in a commercial way and we loose all the experience people have, we are probably having a lot bigger issues as a whole society. But I don't want to deny that it would be nice to have the simplest way of making a small microcontroller yourself (doesn't has to be fast or super easy just doable) would be very cool and could already solve a lot of issues if we would need to restart society from wikipedia.
  • mort96 1y ago
    The comment you're responding to isn't talking about 32 vs 64 bit, but MMU vs no MMU.
• Denvercoder9 1y ago
  If you want a POSIX OS, nommu Linux already isn't it: it doesn't have fork().
  • em3rgent0rdr 1y ago
    Just reading about this...turns out nommu Linux can use vfork(), which unlike fork() shares the parent's address space. Another drawback is that vfork's parent process gets suspended until the child exits or calls execve().
    • actionfromafar 1y ago
      Typicall you always call vfork() + execve(), vfork is pretty useless on its own. Think about it like CreateProcess() on Windows. Windows is another operating system which doesn't support fork(). (Cygwin did unholy things to make it work anyway, IIRC.)
• cout 1y ago
  ELKS can still run on systems without an mmu (though not microcontrollers afaik).
  • snvzz 1y ago
    ELKS runs 16bit x86, including 8086. Note ELKS is not Linux. There's also Fuzix.
• ohdeargodno 1y ago
  Nothing prevents you from maintaining nommu as a fork. The reality of things is, despite your feelings, people have to work on the kernel, daily, and there comes a point where your tinkering needs do not need to be supported in main. You can keep using old versions of the kernel, too. Linux remains open source, extendable, and someone would most likely maintain these ripped out modules. Just not at the expense of the singular maintainer of the subsystem inside the kernel.
  • stephen_g 1y ago
    > there comes a point where your tinkering needs do not need to be supported in main. Linux's master branch is actually called master. Not that it really matters either way (hopefully most people have realised by now that it was never really 'non-inclusive' to normal people) but pays to be accurate.
    • llbbdd 1y ago
      What is meant by inclusive here? I'm having trouble following this comment other than the clarification to the name.
      • stephen_g 1y ago
        The context is that many people (and especially public repositories from US companies) started changing the name to ‘main’ out of a misguided inclusivity push that comes from a niche political theory that says even if words aren’t slurs (which obviously should be avoided), if a word has a meaning that could possibly be connected to anything that could possibly be in any way sensitive to anybody, then we need to protect people from seeing the word. In this case, out of dozens of ways the word is used (others being like ‘masters degree’ or ones that pretty closely match Git’s usage like ‘master recording’ in music), one possible one is ‘slavemaster’, so some started to assert we have to protect people from possibly making the association.
        • bjourne 1y ago
• JoshTriplett 1y ago
  I don't think it makes sense to run Linux on most nommu hardware anymore. It'd make more sense to have a tiny unikernel for running a single application, because on nommu, you don't typically have any application isolation.
  • duskwuff 1y ago
    > on nommu, you don't have any application isolation That isn't necessarily the case. You can have memory protection without a MMU - for instance, most ARM Cortex-M parts have a MPU which can be used to restrict a thread's access to memory ranges or to hardware. What it doesn't get you is memory remapping, which is necessary for features like virtual memory.
    • rasz 1y ago
      virtual memory as in swap is one, but imo bigger one is memory-mapped files
    • tombl 1y ago
      Yeah, nommu absolutely doesn't imply zero memory isolation. I have a kernel port to an architecture with a nonstandard way of doing memory isolation and the existing nommu infrastructure is the only reason it can exist.
• duskwuff 1y ago
  nommu is a neat concept, but basically nobody uses it, and I don't see that as likely to change. There's no real use case for using it in production environments. RTOSes are much better suited for use on nommu hardware, and parts that can run "real" Linux are getting cheaper all the time. If you want a hardware architecture you can easily comprehend - and even build your own implementation of! - that's something which RISC-V handles much better than ARM ever did, nommu or otherwise.
  • speed_spread 1y ago
    There's plenty of use cases for Linux on microcontrollers that will be impossible if nommu is removed. The only reason we don't see more Linux on MCUs is the lack of RAM. RP2350 are very close! Running Linux makes it much easier to develop than a plain RTOS.
    • snvzz 1y ago
      A "plain RTOS" is the better idea most of the time.
      • topspin 1y ago
        That may change. There are some very powerful MCUs appearing, with astonishing features, including hardware virtualization (hypervisors on an MCU,) multicore superscalar, heterogeneous CPU cores with high performance context switching, "AI" co-processors with high throughput buses, and other exotic features. At some point, it might start making sense to level up the OS to (nommu) Linux on these devices. When the applications get complex enough, people find themselves wanting a full blown network stack, full featured storage/file systems that are aligned with non-embedded systems, regular shells, POSIX userland, etc. All of the architectures I have in mind are 32 bit and "nommu"[1]: Cortex-R52/F, Infineon TriCore, Renesas RH850, NXP Power e200. Then you have RISC-V MCU Cambrian Explosion underway. I qualify all this with mays and mights: it hasn't happened yet. I'm just careful not to discount the possibly of a <50 mAh RP Pico 3 booting uLinux, running python and serving web pages being a big hit. [1] They all have various "partition" schemes to isolate banks of RAM for security, reliability, etc., but real MMUs are not offered.
• 762236 1y ago
  Removing nommu makes the kernel simpler and easier to understand.
• trebligdivad 1y ago
  There are some other open OSs, like Zephyr, NuttX and Contiki - so maybe they're the right thing to use for the nommu case rather than Linux?
  • guerrilla 1y ago
    xv6 already runs on RISC-V.
    • throwaway2037 1y ago
      Wow, I am somewhat ashamed to admin that I had never heard of "xv6" until your comment! I found the MIT homepage here: https://pdos.csail.mit.edu/6.1810/2024/xv6.html https://pdos.csail.mit.edu/6.1810/2024/xv6.html Two things standout to me: (1) It was written in 2006. RISC V was not released until 2010 (so says Google). I guess it was ported from x86? (2) Russ Cox is one of the contacts listed on MIT homepage. That guy's digital footprints are enormous.
      • vulcan01 1y ago
        Yes, it was ported from x86. And no, xv6 is not really an OS you want to use in production. There are a lot of design decisions that optimize for pedagogy instead of performance or even reliability (e.g. the kernel is more than happy to panic if/when you get off the "intended path").
    • s20n 1y ago
      xv6-riscv was designed to run on qemu-virt, not real hardware. you'll atleast need to use a fork like https://github.com/jrmenzel/vimix_os https://github.com/jrmenzel/vimix_os to get it to work on a real board.
  • RantyDave 1y ago
    Zephyr is not an OS in the conventional sense, it's more a library you link to so the application can "go".
    • 1y ago
• chasil 1y ago
  This is a foreseeable cataclysm for me, as I retire next year, and the core of our queing system is 64-bit clean (k&r) as it compiled on Alpha, but our client software is very much not. This is a young mans' game, and I am very much not.
• pajko 1y ago
  Why do you need a full blown Linux for that? Much of the provided features are overkill for such embedded systems. Both NuttX and Zephyr provide POSIX(-like) APIs, NuttX has an API quite similar to the Linux kernel, so it should be somewhat easier to port missing stuff (have not tried to do that, the project I was working on got cancelled)
• dragontamer 1y ago
  I don't think software emulation is very important. Let's look at the lowest end chip in the discussion. Almost certainly the SAM9x60.... it is a $5 ARMv5 MMU chip supporting DDR2/LPDDR/DDR3/LPDDR3/PSRAM, a variety of embedded RAM and 'old desktop RAM' and mobile RAM. Yes it's 32-bit but at 600MHz and GBits of RAM support. But you can seriously mass produce a computer under $10 with the chip (so long as you support 4-layer PCBs that can breakout the 0.75mm pitch BGA). As in, the reference design with DDR2 RAM is a 4-layer design. There are a few Rockchips and such that are (rather large) TQFP that are arguably easier. But since DDR RAM is BGA I think it's safe to assume BGA level PCB layout as a point of simplicity. --------- Everything smaller than this category of 32-bit / ARMv5 chips (be it Microchip SAM9x60, or competing Rockchips or AllWinner) is a microcontroller wholly unsuitable for running Linux as we know it. If you cannot reach 64MBs of RAM, Linux is simply unusable. Even for embedded purposes. You really should be using like FreeRTOS or something else at that point. --------- Linux drawing the line at 64MB hardware built within the last 20 years is.... reasonable? Maybe too reasonable. I mean I love the fact that the SAM9x60 is still usable for modern and new designs but somewhere you have to draw the line. ARMv5 is too old to compile even like Node.js. I'm serious when I say this stuff is old. It's an environment already alien to typical Linux users.
  • zgs 1y ago
    Out by a factor of five or more. A $1 Linux capable ARM: https://www.eevblog.com/forum/microcontrollers/the-$1-linux-capable-arm-processor-in-tqfp/ https://www.eevblog.com/forum/microcontrollers/the-$1-linux-... I'd expect that there were even cheaper processors now since it's eight years later.
    • dragontamer 1y ago
      Microchip is always more expensive than the Chinese stuff, but Microchip contributions to Linux are mainline (!!!!), and is often worth the extra few $$$$. Fully open hardware, with mainline Linux open source drivers. It's hard to beat SAM9x60 in openness, documentation and overall usability. It's specs are weaker but keeping up with mainline Linux is very, very relevant. Especially in this discussion
• noobermin 1y ago
  You're not alone, I feel the same way. I think the future if linux really will need to remove nommu would be a fork. I'm not sure if there's the community for that though.l
• pjmlp 1y ago
  There are plenty of FOSS POSIX like for such systems. Most likely I won't be around this realm when that takes shape, but I predict the GNU/Linux explosion replacing UNIX was only a phase in computing history, eventually when everyone responsible for its success fades away, other agendas will take over. It is no accident that the alternatives I mention, are all based on copyleft licenses.
• MisterTea 1y ago
  > Maybe we need a simple posix os that would run on a simple open dedicated hardware that can be comprehended by a small group of human beings. Simple and POSIX would be a BSD like NetBSD or OpenBSD. This is why I gravitated to Plan 9. Overall a better design for a networked world and can be understood by a single developer. People can and have maintained their own forks. Its very simple, small and cross platform was baked in from day one. 9P makes everything into a IO socket organized as a tree of names objects. Thankfully it's not POSIX which IMO is not worth dragging along for decades. You can port Unix things with libraries. It also abandons the typewriter terminal and instead uses graphics. A fork, 9front, is not abandoning 32 bit any time soon AFIK. I netboot an older Industrial computer that is a 400MHz Geode (32 bit x86) with 128 MB RAM and it runs 9front just fine. Its not perfect and lacks features but that stands to reason for any niche OS without a large community. Figure out what is missing for you and work on fixing it - patches welcome.
• lproven 1y ago
  > Maybe we need a simple posix os that would run on a simple open dedicated hardware that can be comprehended by a small group of human beings. That was part of the plan for Minix 3. Clean separation in a microkernel, simple enough for teaching students, but robust. But Intel used it and gave nothing back, and AST retired. :-(