5 ms·

Ubuntu 25.10 Raises RISC-V Profile Requirements

128 points by bundie 1y ago

deleted 1y ago
[deleted]
fithisux 1y ago
Still, no consumer based RV23 mini-ITX or micro-ATX or ATX form factor devices. And Orange PI 2 has a GFX blob issue.
- ojn 1y ago
  It's worse than that -- there is not a single piece of hardware that implements RVA23 available to be bought on the market today. There are SoCs on the market that implement RVV (Vector extensions), and SoCs on the market that implement H (Hypervisor extensions). There are no SoCs on the market that implement both at the same time. And both are mandatory for RVA23. I'd love to be proven wrong on the hardware availability. If there's hardware to be bought in western countries that implements both RVV and H, please let me know.
  - dietr1ch 1y ago
    > It's worse than that -- there is not a single piece of hardware that implements RVA23 available to be bought on the market today. I think that's fine, as an outsider without any RISC-V board around, alignment in the future seems better than a board out today given performance is AFAIK still awfully subpar. As a potential consumer all I want is that by the time RISC-V really hits the market people don't start hitting edge cases like toes on furniture with missing extensions that ended up being critical to properly run the software they need. I don't want another shitshow like USB-C fast-charging where consumers can't easily tell if a cable will work fine or end up in a slow charge fallback. I'd rather see RISC-V for the more general public coming out later than starting with the wrong foot.
- snvzz 1y ago
  >Still, no consumer based RV23 mini-ITX or micro-ATX or ATX form factor devices. Sure. But there are RVA22+V such devices. RVA23 will eventually succeed these. Many IP vendors announced RVA23 cores, but understand that the process from having a core design available for licensing to having a chip is very long, measured in years. Among the designs that are further down in the pipeline of development, a highlight is Tenstorrent's Ascalon. According to them, a tapeout is "imminent". This was in the RISC-V Summit EU a few weeks ago. That'd mean RVA23 chips competitive with Zen5 in early 2026.
  - dmitrygr 1y ago
    > That'd mean RVA23 chips competitive with Zen5 in early 2026 allegedly competitive, according to the vendor who is not impartial and with no actual benchmarks in existence to prove anything.
    - camel-cdr 1y ago
      None of them are competitive with Zen5 on a per core basis, if you compare the published SPEC results. Veyron V2 has comparable perf per GHz to Zen4/5, but at a lower clock frequency (N4: 3.25, N3: 3.85): https://www.ventanamicro.com/technology/risc-v-cpu-ip/ https://www.ventanamicro.com/technology/risc-v-cpu-ip/ Ascalon is about half as fast as Veyron V2, partially due to lower clock frequency (~2.6 GHz): https://riscv.or.jp/wp-content/uploads/Japan_RISC-V_day_Spring_2025_compressed.pdf https://riscv.or.jp/wp-content/uploads/Japan_RISC-V_day_Spri... It's really more designed as a "we need a decently fast and efficient CPU for our AI accelerator" then a "let's build the fastes CPU possible".
    - fithisux 1y ago
      This is not a problem. We are not running supercomputers at home. We need to be able Math software on modern open hardware We need to be able to program with a better assembly We need to be able to have predictable code generation from our compilers We need to play with a new architecture and port software as an exercise We need to have choice
      - 1y ago
somanyphotons 1y ago
RVA23 is actually a decent ISA for linux machines for the long term, RVA20 was not. Presumably there's going to be some hardware releases later this year that Ubuntu has early knowledge of. Does this line up with what riscv android will also require?
- dmitrygr 1y ago
  > that Ubuntu has early knowledge of. They aren’t big enough to get advance notice of hardware from any serious SoC makers. So I bet not.
- kragen 1y ago
  Seems unlikely.
- snvzz 1y ago
  >Does this line up with what riscv android will also require? AIUI both Google and Microsoft selected RVA23 as baseline.
  - sanxiyn 1y ago
    Google quote from https://riscv.org/riscv-news/2024/10/risc-v-announces-ratification-of-the-rva23-profile-standard/ https://riscv.org/riscv-news/2024/10/risc-v-announces-ratifi... > "Google is delighted to see the ratification of the RVA23 Profile," said Lars Bergstrom, Director of Engineering, Google. "This profile has been the result of a broad industry collaboration, and is now the baseline requirement for the Android RISC-V Application Binary Interface (ABI)."
- mosura 1y ago
  > RVA23 is actually a decent ISA for linux machines for the long term, RVA20 was not. This is setting it all up to happen again with whatever is found to be wrong with RVA23.
  - boredatoms 1y ago
    RVA20 was missing generally expected features, RVA23 isnt RVA30 is N+1, presumably we wont see shipping devices for that until the early 2030s
csense 1y ago
Can you write a kernel patch / driver to trap the unsupported instructions and provide software implementations?
- karlgkk 1y ago
  Rva20 lacks vector support and hypervisor instructions, among other things. You’re welcome to put a ton of effort in for dogshit performance on a bunch or $35 SBCs but the rest of us will just upgrade And don’t worry, some vendor won’t come in and magically save you - fedora is eyeing rv22 as their baseline.
  - stefan_ 1y ago
    That's the problem with open source, a bunch of people who once in their life want to "do it right" (right never comes). No adults in the room to say "this is what you got". From a billion python packages in distribution package managers to broken screen sharing in Wayland, "right" isn't even what anyone wants.
  - slyall 1y ago
    The Linux Kernel has math coprocessor emulation (mainly floating point stuff) that can be enabled if your CPU doesn't include it. This was common with consumer CPUs in the 1990s and some embedded CPUs today. Link here, although I'm sure it existed well before 2.6.12 https://www.kernelconfig.io/config_math_emulation https://www.kernelconfig.io/config_math_emulation
  - cwillu 1y ago
    [flagged]
  - CursedSilicon 1y ago
    Can you rephrase your answer in a way that isn't brutally and unnecessarily hostile?
    - karlgkk 1y ago
      Honestly, it's because of the "can you do a ton of unpaid work to support my niche, non-commercial application" attitude of the OP, which I find to be extremely distasteful. It's something I deal with frequently. I should not have taken it out on OP and I agree I could have communicated that much better. Unfortunately, I can't edit my post or I would rephrase it significantly. Sorry to user "Levitating", I was being a dick.
shirro 1y ago
Seems like a tough call for operating systems to do this when things are moving so fast. With risc-v its probably better to be future looking given current limitations but if a lower spec risc-v exploded in popularity you miss out. Debian decided, probably very sensibly at the time, to set their minimum target for their 32 bit arm hardfloat distro to armv7. I guess hardly anyone used armv6 with hardware floating point apart from some obscure Broadcom chip. Then the original Raspberry Pi was released, moved an insane number of units, and Debian users would have been stuck with no hardware floating point. Fortunately Mike Thompson recompiled Debian for armv6 with hardfloat and that Debian fork (Raspbian) ended up becoming the basis for the official Raspberry Pi OS.
- saurik 1y ago
  The original two generations of iPhone were armv6 with hardware floating point, so that always felt to me like the sane baseline. Android wasn't using hardware floating point on armv6, but I think that was only because the compilers they had sucked (an issue that didn't apply to Apple), and many/most of the devices in fact shipped with the same hardware. I dunno... like, I don't know exactly what went into Debian's decision there, but I could see it having been made for the wrong reasons: looking at what software had been deployed rather than what hardware was common?
  - sanxiyn 1y ago
    You can look at Debian's reasoning here: https://wiki.debian.org/ArmHardFloatPort https://wiki.debian.org/ArmHardFloatPort. As I understand, the decision was mostly based on hardware.
    - stingraycharles 1y ago
      I just read it, seems like an unfortunate chain of events. They tried to look forward a little bit by looking at the current generation of hardware that’s out there, and didn’t anticipate an older chip to become that massively popular.
    - saurik 1y ago
Levitating 1y ago
I am really hoping there are is some unannounced hardware that Ubuntu is aware of.
throwaway48476 1y ago
This will keep happening as the omissions in the risc v application processor standard are fleshed out.
delfinom 1y ago
Classic canonical trying to fork a sector, again
- pjmlp 1y ago
  FOSS advocates are free to vote with their adoption of systems that decide otherwise.
johnklos 1y ago
Holy cow! Ubuntu really takes their hardware gatekeeping seriously. Of course we'll hear from the apologists about how much extra work supporting "low end" systems is - think of the developers! think of Ubuntu's bottom line! > Admittedly there is one big rub: the range of RISC-V devices with RVA23 support is, at the time or writing this, near non-existent. They couldn't even wait for hardware to be available before doing this? So basically Ubuntu 25.10 only runs on hardware that doesn't yet exist. Nice. > Focusing future Ubuntu support to devices that have more capable RISC-V profile sets will further position the distro as the de-facto OS on the platform. ...or everyone will move to something else - ANYTHING else - because we don't want to replace our brand new devices just to run Ubuntu.
- snvzz 1y ago
  >...or everyone will move to something else - ANYTHING else - because we don't want to replace our brand new devices just to run Ubuntu. Everyone now is nobody tomorrow. Right now, the few RISC-V boards are in the hands of developers and enthusiasts. In the future, RISC-V will continue to grow, into mass-market. Ubuntu recognizes the importance of being able to fully take advantage of RVA23, a fully capable ISA comparable to x86-64v4 and ARMv9.
  - johnklos 1y ago
    Salespeak ;)
vitali2y 1y ago
[dead]
londons_explore 1y ago
Why can't these older processors be supported via a software shim for unrecognised instructions? It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all.
- snvzz 1y ago
  >Why can't these older processors be supported via a software shim for unrecognised instructions? It can. It's just this shim is out of scope for Ubuntu. Refer to opensbi instruction emulation. >It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all. With features like vector instructions or pointer masking, we're talking a non-trivial slowdown.
- camel-cdr 1y ago
  > It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all. The difference on geekbench is 2x and not every benchmark has been optimized for RVV yet: https://browser.geekbench.com/v6/cpu/compare/10681749?baseline=7313480 https://browser.geekbench.com/v6/cpu/compare/10681749?baseli... (same hardware, one using the newer geekbench version that can take advantage of RVA22+V)
- brucehoult 1y ago
  Because new instructions such as `c.lb{u}` and `c.sb` and `c.{s,z}ext.{b,h,w}` are going to be thoroughly mixed in all over the place. Probably the (kinda) conditional move `czero.eqz` and `czero.nez` too.
deleted 1y ago
[deleted]

128 points by bundie 1y ago

deleted 1y ago

[deleted]

fithisux 1y ago

Still, no consumer based RV23 mini-ITX or micro-ATX or ATX form factor devices. And Orange PI 2 has a GFX blob issue.

ojn 1y ago
It's worse than that -- there is not a single piece of hardware that implements RVA23 available to be bought on the market today. There are SoCs on the market that implement RVV (Vector extensions), and SoCs on the market that implement H (Hypervisor extensions). There are no SoCs on the market that implement both at the same time. And both are mandatory for RVA23. I'd love to be proven wrong on the hardware availability. If there's hardware to be bought in western countries that implements both RVV and H, please let me know.
- dietr1ch 1y ago
  > It's worse than that -- there is not a single piece of hardware that implements RVA23 available to be bought on the market today. I think that's fine, as an outsider without any RISC-V board around, alignment in the future seems better than a board out today given performance is AFAIK still awfully subpar. As a potential consumer all I want is that by the time RISC-V really hits the market people don't start hitting edge cases like toes on furniture with missing extensions that ended up being critical to properly run the software they need. I don't want another shitshow like USB-C fast-charging where consumers can't easily tell if a cable will work fine or end up in a slow charge fallback. I'd rather see RISC-V for the more general public coming out later than starting with the wrong foot.
snvzz 1y ago
>Still, no consumer based RV23 mini-ITX or micro-ATX or ATX form factor devices. Sure. But there are RVA22+V such devices. RVA23 will eventually succeed these. Many IP vendors announced RVA23 cores, but understand that the process from having a core design available for licensing to having a chip is very long, measured in years. Among the designs that are further down in the pipeline of development, a highlight is Tenstorrent's Ascalon. According to them, a tapeout is "imminent". This was in the RISC-V Summit EU a few weeks ago. That'd mean RVA23 chips competitive with Zen5 in early 2026.
- dmitrygr 1y ago
  > That'd mean RVA23 chips competitive with Zen5 in early 2026 allegedly competitive, according to the vendor who is not impartial and with no actual benchmarks in existence to prove anything.
  - camel-cdr 1y ago
    None of them are competitive with Zen5 on a per core basis, if you compare the published SPEC results. Veyron V2 has comparable perf per GHz to Zen4/5, but at a lower clock frequency (N4: 3.25, N3: 3.85): https://www.ventanamicro.com/technology/risc-v-cpu-ip/ https://www.ventanamicro.com/technology/risc-v-cpu-ip/ Ascalon is about half as fast as Veyron V2, partially due to lower clock frequency (~2.6 GHz): https://riscv.or.jp/wp-content/uploads/Japan_RISC-V_day_Spring_2025_compressed.pdf https://riscv.or.jp/wp-content/uploads/Japan_RISC-V_day_Spri... It's really more designed as a "we need a decently fast and efficient CPU for our AI accelerator" then a "let's build the fastes CPU possible".
  - fithisux 1y ago
    This is not a problem. We are not running supercomputers at home. We need to be able Math software on modern open hardware We need to be able to program with a better assembly We need to be able to have predictable code generation from our compilers We need to play with a new architecture and port software as an exercise We need to have choice
    - 1y ago

somanyphotons 1y ago

RVA23 is actually a decent ISA for linux machines for the long term, RVA20 was not. Presumably there's going to be some hardware releases later this year that Ubuntu has early knowledge of. Does this line up with what riscv android will also require?

dmitrygr 1y ago
> that Ubuntu has early knowledge of. They aren’t big enough to get advance notice of hardware from any serious SoC makers. So I bet not.
kragen 1y ago
Seems unlikely.
snvzz 1y ago
>Does this line up with what riscv android will also require? AIUI both Google and Microsoft selected RVA23 as baseline.
- sanxiyn 1y ago
  Google quote from https://riscv.org/riscv-news/2024/10/risc-v-announces-ratification-of-the-rva23-profile-standard/ https://riscv.org/riscv-news/2024/10/risc-v-announces-ratifi... > "Google is delighted to see the ratification of the RVA23 Profile," said Lars Bergstrom, Director of Engineering, Google. "This profile has been the result of a broad industry collaboration, and is now the baseline requirement for the Android RISC-V Application Binary Interface (ABI)."
mosura 1y ago
> RVA23 is actually a decent ISA for linux machines for the long term, RVA20 was not. This is setting it all up to happen again with whatever is found to be wrong with RVA23.
- boredatoms 1y ago
  RVA20 was missing generally expected features, RVA23 isnt RVA30 is N+1, presumably we wont see shipping devices for that until the early 2030s

csense 1y ago

Can you write a kernel patch / driver to trap the unsupported instructions and provide software implementations?

karlgkk 1y ago
Rva20 lacks vector support and hypervisor instructions, among other things. You’re welcome to put a ton of effort in for dogshit performance on a bunch or $35 SBCs but the rest of us will just upgrade And don’t worry, some vendor won’t come in and magically save you - fedora is eyeing rv22 as their baseline.
- stefan_ 1y ago
  That's the problem with open source, a bunch of people who once in their life want to "do it right" (right never comes). No adults in the room to say "this is what you got". From a billion python packages in distribution package managers to broken screen sharing in Wayland, "right" isn't even what anyone wants.
- slyall 1y ago
  The Linux Kernel has math coprocessor emulation (mainly floating point stuff) that can be enabled if your CPU doesn't include it. This was common with consumer CPUs in the 1990s and some embedded CPUs today. Link here, although I'm sure it existed well before 2.6.12 https://www.kernelconfig.io/config_math_emulation https://www.kernelconfig.io/config_math_emulation
- cwillu 1y ago
  [flagged]
- CursedSilicon 1y ago
  Can you rephrase your answer in a way that isn't brutally and unnecessarily hostile?
  - karlgkk 1y ago
    Honestly, it's because of the "can you do a ton of unpaid work to support my niche, non-commercial application" attitude of the OP, which I find to be extremely distasteful. It's something I deal with frequently. I should not have taken it out on OP and I agree I could have communicated that much better. Unfortunately, I can't edit my post or I would rephrase it significantly. Sorry to user "Levitating", I was being a dick.

shirro 1y ago

Seems like a tough call for operating systems to do this when things are moving so fast. With risc-v its probably better to be future looking given current limitations but if a lower spec risc-v exploded in popularity you miss out. Debian decided, probably very sensibly at the time, to set their minimum target for their 32 bit arm hardfloat distro to armv7. I guess hardly anyone used armv6 with hardware floating point apart from some obscure Broadcom chip. Then the original Raspberry Pi was released, moved an insane number of units, and Debian users would have been stuck with no hardware floating point. Fortunately Mike Thompson recompiled Debian for armv6 with hardfloat and that Debian fork (Raspbian) ended up becoming the basis for the official Raspberry Pi OS.

saurik 1y ago
The original two generations of iPhone were armv6 with hardware floating point, so that always felt to me like the sane baseline. Android wasn't using hardware floating point on armv6, but I think that was only because the compilers they had sucked (an issue that didn't apply to Apple), and many/most of the devices in fact shipped with the same hardware. I dunno... like, I don't know exactly what went into Debian's decision there, but I could see it having been made for the wrong reasons: looking at what software had been deployed rather than what hardware was common?
- sanxiyn 1y ago
  You can look at Debian's reasoning here: https://wiki.debian.org/ArmHardFloatPort https://wiki.debian.org/ArmHardFloatPort. As I understand, the decision was mostly based on hardware.
  - stingraycharles 1y ago
    I just read it, seems like an unfortunate chain of events. They tried to look forward a little bit by looking at the current generation of hardware that’s out there, and didn’t anticipate an older chip to become that massively popular.
  - saurik 1y ago

Levitating 1y ago

I am really hoping there are is some unannounced hardware that Ubuntu is aware of.

throwaway48476 1y ago

This will keep happening as the omissions in the risc v application processor standard are fleshed out.

delfinom 1y ago

Classic canonical trying to fork a sector, again

pjmlp 1y ago
FOSS advocates are free to vote with their adoption of systems that decide otherwise.

johnklos 1y ago

Holy cow! Ubuntu really takes their hardware gatekeeping seriously. Of course we'll hear from the apologists about how much extra work supporting "low end" systems is - think of the developers! think of Ubuntu's bottom line! > Admittedly there is one big rub: the range of RISC-V devices with RVA23 support is, at the time or writing this, near non-existent. They couldn't even wait for hardware to be available before doing this? So basically Ubuntu 25.10 only runs on hardware that doesn't yet exist. Nice. > Focusing future Ubuntu support to devices that have more capable RISC-V profile sets will further position the distro as the de-facto OS on the platform. ...or everyone will move to something else - ANYTHING else - because we don't want to replace our brand new devices just to run Ubuntu.

snvzz 1y ago
>...or everyone will move to something else - ANYTHING else - because we don't want to replace our brand new devices just to run Ubuntu. Everyone now is nobody tomorrow. Right now, the few RISC-V boards are in the hands of developers and enthusiasts. In the future, RISC-V will continue to grow, into mass-market. Ubuntu recognizes the importance of being able to fully take advantage of RVA23, a fully capable ISA comparable to x86-64v4 and ARMv9.
- johnklos 1y ago
  Salespeak ;)

vitali2y 1y ago

[dead]

londons_explore 1y ago

Why can't these older processors be supported via a software shim for unrecognised instructions? It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all.

snvzz 1y ago
>Why can't these older processors be supported via a software shim for unrecognised instructions? It can. It's just this shim is out of scope for Ubuntu. Refer to opensbi instruction emulation. >It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all. With features like vector instructions or pointer masking, we're talking a non-trivial slowdown.
camel-cdr 1y ago
> It is far better for software to run with a couple of percent slowdown on old cpus only than not run at all. The difference on geekbench is 2x and not every benchmark has been optimized for RVV yet: https://browser.geekbench.com/v6/cpu/compare/10681749?baseline=7313480 https://browser.geekbench.com/v6/cpu/compare/10681749?baseli... (same hardware, one using the newer geekbench version that can take advantage of RVA22+V)
brucehoult 1y ago
Because new instructions such as `c.lb{u}` and `c.sb` and `c.{s,z}ext.{b,h,w}` are going to be thoroughly mixed in all over the place. Probably the (kinda) conditional move `czero.eqz` and `czero.nez` too.

deleted 1y ago

[deleted]