On the userland side, there is some good progress of using thunking to run 32-bit Windows programs in Wine on Linux without the need for 32-bit libraries (the only edge case remaining is thunking 32-bit OpenGL which is lacking needed extensions for acceptable performance). But the same can't be said for a bunch of legacy 32-bit native Linux stuff like games which commonly have no source to rebuild them.
May be someone can develop such thunking for legacy Linux userland.
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, as individuals, remain in control. The more complex things are, the less freedom we have.
It's not a well argumented thought, just a nagging feeling.
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. A system that would allow communication, simple media processing and productivity.
These days it feels like we are at a tipping point for open computing. It feels like being a frog in hot water.
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.
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
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.
> 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.
Linux has become the dominant operating system for a wide range of devices, even though other options like FreeRTOS or the BSD family seem more specialized. The widespread adoption of Linux suggests that a single, versatile operating system may be more practical than several niche ones. However, the decision to drop support for certain hardware because it complicates maintenance, as seen here, would seem to contradict the benefit of a unified system. I wouldn't be surprised if it really just results in more Linux forks - Android is already at the point of not quite following mainline.
Funny, I remember 32 bits being 'the future', now it is the distant past. I think they should keep it all around, and keep it buildable. Though I totally understand the pressure to get rid of it I think having at least one one-size-fits-all OS is a very useful thing to have. You never know what the future will bring.
I can’t help but wonder if kernel devs realize how much this discussion sounds like something you’d expect from Apple. They are talking about obsoleting hardware not because it’s fundamentally broken, but because it no longer fits neatly into a roadmap. Open source has always been about making hardware outlive commercial interest and let it run long after the hardware vendor abandons it.
I'm pretty shocked to see comments like "the RAM for a 32-bit system costs more than the CPU itself", but open source isn’t supposed to be about market pricing or what’s convenient for vendors; it’s about giving users the freedom to decide what’s worth running.
I understand that maintainers don’t want to drag around unmaintained code forever, and that testing on rare hardware is difficult. But if the code already exists and is working, is it really that costly to just not break it? The kernel's history is full of examples where obscure architectures and configs were kept alive for decades with minimal intervention. Removing them feels like a philosophical shift, especially when modern hardware is more locked down and has a variety of black box systems running behind it like Intel ME and AMD PSP.
The Apple Watch has 32-bit memory addressing (and 64-bit integer arithmetic -- it's ILP32). Granted it doesn't run Linux, but it's a very very modern piece of hardware, in production, and very profitable.
Same for WASM -- 32-bit pointers, 64-bit integers.
Both of these platforms have a 32-bit address space -- both for physical addresses and virtual addresses.
Ripping out support for 32-bit pointers seems like a bad idea.
> One other possibility is to drop high memory, but allow the extra physical memory to be used as a zram swap device. That would not be as efficient as accessing the memory directly, but it is relatively simple and would make it possible to drop the complexity of high memory.
Wild, like some kind of virtual cache. Reminds me a bit of the old Macintosh 68k accelerators; sometimes they included their own (faster) memory and you could use the existing sticks as a RAM disk.
It's the end of an area, Linux used to be this thing that was running on quite anything and allowing to salvage old computers.
I think that there is a shitload of old desktop and laptop computers from 10 to 15 yrs that are still usable only with a linux distribution and that will not be true anymore.
Now Linux will be in the same lane as osx and windows running after the last shiny new things, and being like: if you want it, buy a new machine that will support it.
In my experience, the 10-15 year old salvaged computer that still works okay with GNU/Linux is increasingly a 64 bit machine.
Case in point, I'm writing on a x86_64 laptop that was a free give away to me about a year ago with a CPU release year that is 2012.
I have personally given away a x86_64 desktop unit years ago that was even older, might have had DDR1 memory.
Circa 2013 my old company was gifted a x86_64 motherboard with DDR2 memory that ended up serving as our in-office server for many years. We maxed the RAM (8GB) and at some point bought a CPU upgrade on ebay that gave us hardware virtualization extensions.
So Arnd Bergmann thinks that all future systems, embedded included, will have 64 bit CPUs? Or will embedded just stop using Linux and move to the BSDs?
> The kernel is still adding support for some 32-bit boards, he said, but at least ten new 64-bit boards gain support for each 32-bit one.
And
> To summarize, he said, the kernel will have to retain support for armv7 systems for at least another ten years. Boards are still being produced with these CPUs, so even ten years may be optimistic for removal. Everything else, he said, will probably fade away sooner than that.
This seems pretty uninformed on the embedded side - the speaker is I'm sure very qualified generally but it sounds like mostly on the server/desktop side of things.
Like on Armv7-M it's said "Nobody is building anything with this kind of hardware now" - this is just wrong to the point of ridiculousness. Thousands of new products will be designed using these microcontrollers and still billions of units will be produced with them in them - now, true that almost none of those will run Linux on those MCUs but it's crazy to say "nobody" is building things with them. Many of course are moving to Armv8-M microcontrollers but those are 32 bit too!
On the Linux side, there are things like the AMD/Xillinx Zynq-7000 series that will be supported for many years to come.
It's not the worst idea in the world to deprecate support for 32-bit x86 but it is not time to remove it for ARM for many years yet.
It seems like it takes just one user using a certain piece of hardware to justify it being supported in the kernel, which is surprising to me. The cost to kernel dev velocity is not weighed more heavily against that?
One known user. Linux doesn't have automatic telemetry in every distro (or even most distros), the kernel devs don't really know how many people use. So if they know of one user, there are probably more users that just haven't come to their attention on the mailing lists.
I have 32 bits support on my x86_64 gaming ring, _ONLY_ for the steam client.
The "steam client" is still a 32 bits ELF executable, which statically loads openGL and x11 libs... (namely not even a wayland->x11 fallback or a opengl->CPU rendering).
We would be all better with a nogfx static PIE executable, even a nogfx dynamic PIE executable if they want to explore the ELF setup of a distro.
> There are still some people who need to run 32-bit applications that cannot be updated; the solution he has been pushing people toward is to run a 32-bit user space on a 64-bit kernel. This is a good solution for memory-constrained systems; switching to 32-bit halves the memory usage of the system. Since, on most systems, almost all memory is used by user space, running a 64-bit kernel has a relatively small cost. Please, he asked, do not run 32-bit kernels on 64-bit processors.
Ohhh yes!
So, a couple of weeks ago I came across a discussion where some distro (I don't remember which one) contemplated removing 32-bit user space support, suggesting to users to simply run a VM running a 32 bit Linux instead. It was a stupid suggestion then, and this statement is a nice authorative answer from the kernel side, where such suggestions can be shoved to.
I think this is premature and a big mistake for Linux.
The costs of distros and the kernel steadily dropping older x86 support over the last few years never causes an outcry but it's an erosion of what made Linux great. Especially for non-English speaking people in less developed countries.
Open-source maintenance is not a obligation, but it's sad there is not more people pushing to maintain support. Especially for the "universal operating system" Debian which was previously a gold standard in architecture support.
I maintain a relatively popular live Linux distro based on Ubuntu and due to user demand will look into a NetBSD variant to continue support (as suggested in this thread), potentially to support legacy 586 and 686 too.
Though a Debian 13 "Trixie" variant with a custom compiled 686 kernel will be much easier than switching to NetBSD, it appears like NetBSD has more commitment to longer-term arch support.
It would be wonderful to develop systems (eg emulation) to make it practical to support architectures as close to indefinitely as possible.
It does feel like a big end of an era moment for Linux and distros here, with the project following the kind of decision making of big tech companies rather than the ideals of computer enthusiasts.
Right now these deprecation decisions will directly make me spend time working at layers of abstraction I wasn't intending to in order to mitigate the upstream deprecations of the kernels and distros. The reason I have used the kernel and distros like Debian has been to offload that work to the specialist maintainers of the open-source community.
It's interesting that only objection for removing big endian is from IBM and their mainframe and PowerPC. Also big endian is restricted to 32bit in Linux kernel.
I have some 32-bit systems (arm and x86), and it looks like I’m going to use them till the hardware breaks. The old x86 system is power hungry and inefficient, but the thing is, I power it on very occasionally. Like for half a day once a month. So its power consumption isn’t an issue. Probably I should consider some BSD for it. But what should I do with an arm system, if that’s applicable, I have no idea.
36 comments
[ 5.6 ms ] story [ 64.0 ms ] threadMay be someone can develop such thunking for legacy Linux userland.
It will be relegated to the computing dustbin like non-8-bit bytes and EBCDIC.
Main-core computing is vastly more homogenous than when I was born almost 50 years ago. I guess that's a natural progression for technology.
Hey, you! You're supposed to be dead!
https://wiki.netbsd.org/ports/evbarm/
It's not a well argumented thought, just a nagging feeling.
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. A system that would allow communication, simple media processing and productivity.
These days it feels like we are at a tipping point for open computing. It feels like being a frog in hot water.
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.
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.
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.
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. :-(
Compared to ARM-based systems? Nope.
I saw this last in SmartOS.
I'm pretty shocked to see comments like "the RAM for a 32-bit system costs more than the CPU itself", but open source isn’t supposed to be about market pricing or what’s convenient for vendors; it’s about giving users the freedom to decide what’s worth running.
I understand that maintainers don’t want to drag around unmaintained code forever, and that testing on rare hardware is difficult. But if the code already exists and is working, is it really that costly to just not break it? The kernel's history is full of examples where obscure architectures and configs were kept alive for decades with minimal intervention. Removing them feels like a philosophical shift, especially when modern hardware is more locked down and has a variety of black box systems running behind it like Intel ME and AMD PSP.
Same for WASM -- 32-bit pointers, 64-bit integers.
Both of these platforms have a 32-bit address space -- both for physical addresses and virtual addresses.
Ripping out support for 32-bit pointers seems like a bad idea.
Wild, like some kind of virtual cache. Reminds me a bit of the old Macintosh 68k accelerators; sometimes they included their own (faster) memory and you could use the existing sticks as a RAM disk.
I think that there is a shitload of old desktop and laptop computers from 10 to 15 yrs that are still usable only with a linux distribution and that will not be true anymore.
Now Linux will be in the same lane as osx and windows running after the last shiny new things, and being like: if you want it, buy a new machine that will support it.
Case in point, I'm writing on a x86_64 laptop that was a free give away to me about a year ago with a CPU release year that is 2012.
I have personally given away a x86_64 desktop unit years ago that was even older, might have had DDR1 memory.
Circa 2013 my old company was gifted a x86_64 motherboard with DDR2 memory that ended up serving as our in-office server for many years. We maxed the RAM (8GB) and at some point bought a CPU upgrade on ebay that gave us hardware virtualization extensions.
> The kernel is still adding support for some 32-bit boards, he said, but at least ten new 64-bit boards gain support for each 32-bit one.
And
> To summarize, he said, the kernel will have to retain support for armv7 systems for at least another ten years. Boards are still being produced with these CPUs, so even ten years may be optimistic for removal. Everything else, he said, will probably fade away sooner than that.
So, no, he does not think that at all.
Like on Armv7-M it's said "Nobody is building anything with this kind of hardware now" - this is just wrong to the point of ridiculousness. Thousands of new products will be designed using these microcontrollers and still billions of units will be produced with them in them - now, true that almost none of those will run Linux on those MCUs but it's crazy to say "nobody" is building things with them. Many of course are moving to Armv8-M microcontrollers but those are 32 bit too!
On the Linux side, there are things like the AMD/Xillinx Zynq-7000 series that will be supported for many years to come.
It's not the worst idea in the world to deprecate support for 32-bit x86 but it is not time to remove it for ARM for many years yet.
The "steam client" is still a 32 bits ELF executable, which statically loads openGL and x11 libs... (namely not even a wayland->x11 fallback or a opengl->CPU rendering).
We would be all better with a nogfx static PIE executable, even a nogfx dynamic PIE executable if they want to explore the ELF setup of a distro.
Ohhh yes!
So, a couple of weeks ago I came across a discussion where some distro (I don't remember which one) contemplated removing 32-bit user space support, suggesting to users to simply run a VM running a 32 bit Linux instead. It was a stupid suggestion then, and this statement is a nice authorative answer from the kernel side, where such suggestions can be shoved to.
The costs of distros and the kernel steadily dropping older x86 support over the last few years never causes an outcry but it's an erosion of what made Linux great. Especially for non-English speaking people in less developed countries.
Open-source maintenance is not a obligation, but it's sad there is not more people pushing to maintain support. Especially for the "universal operating system" Debian which was previously a gold standard in architecture support.
I maintain a relatively popular live Linux distro based on Ubuntu and due to user demand will look into a NetBSD variant to continue support (as suggested in this thread), potentially to support legacy 586 and 686 too.
Though a Debian 13 "Trixie" variant with a custom compiled 686 kernel will be much easier than switching to NetBSD, it appears like NetBSD has more commitment to longer-term arch support.
It would be wonderful to develop systems (eg emulation) to make it practical to support architectures as close to indefinitely as possible.
It does feel like a big end of an era moment for Linux and distros here, with the project following the kind of decision making of big tech companies rather than the ideals of computer enthusiasts.
Right now these deprecation decisions will directly make me spend time working at layers of abstraction I wasn't intending to in order to mitigate the upstream deprecations of the kernels and distros. The reason I have used the kernel and distros like Debian has been to offload that work to the specialist maintainers of the open-source community.