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Real-Time Support "PREEMPT_RT" For Linux Held Up Due To Lack Of Funding

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  • Real-Time Support "PREEMPT_RT" For Linux Held Up Due To Lack Of Funding

    Phoronix: Real-Time Support "PREEMPT_RT" For Linux Held Up Due To Lack Of Funding

    While there was kernel talk of merging the PREEMPT_RT code in 2020 for this real-time functionality for the Linux kernel, among other times in the past that has yet to happen. These "RT" patches have long been maintained out-of-tree but it turns out that while in the past it was seemingly close for merging, that effort has stalled for lack of funding...

    https://www.phoronix.com/scan.php?pa...-Lack-Of-Funds

  • #2
    I used to work with a guy who took part in Xenomai software stack (that is, a RT kernel that's running Linux in one of its skin), and discussed about preempt_rt.
    His opinions were quite bad about PREEMPT_RT because it had so many implication to try to skin a cat as a dog, that it was not viable for Linux (the underlying kernel is not thought for realtime, and the patch might appear to work for the base stuff, but it'll always break in some obscure driver that wasn't written with realtime preemption in mind).

    So the initiative for Xenomai was, for him, a lot better. Instead of trying (and exhausting) to make a *huge* Linux realtime, it's much easier to make a small kernel realtime, and have one of the task for this kernel to run linux and pre-empt linux when a RT task is ready to run.

    From Xenomai's relative success, I think he was right in his opinion here.

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    • #3
      This is quite unfortunate. I really hope the situation gets solved.

      I really want PREEMPT_RT continues to be developed and finally merged, even better if this year.

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      • #4
        Yeah, the RT patches are essential for live audio performances, I really hope it gets sorted out

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        • #5
          Wow...no funding that is a strange surprise - so much companies are profiting from RT Linux.

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          • #6
            This reminds me openssl. I suspect he'll need a heartbleed moment for traction. But I hope it doesn't need to get that far.
            https://arstechnica.com/information-...-fund-openssl/

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            • #7
              Originally posted by kbios View Post
              Yeah, the RT patches are essential for live audio performances, I really hope it gets sorted out
              I'm just throwing the opinion of Ubuntu Studio's take on this here for further discussion:
              About RealTime Kernels


              Early on in Linux audio production, Real-Time kernels were the only way to get low- and no-latency audio for professional audio applications. However, since Linux 2.6, the real-time stack has been part of the Linux kernel, having a kernel patched with a real-time stack is no longer necessary.


              RealTime Kernels Still Exist


              However, there continued to be a demand for real-time kernels with a special patch. A patch does exist to enable process to have real-time process access to any process requesting it. This is good for applicance-like applications, such as audio mixers that use Linux (the Behringer X-series mixers and the Allen & Heath iLive series mixers are good examples). For desktop computer use, THIS IS A BAD IDEA.


              Security Implications


              All it would take is one malicious process to execute and take advantage of the real-time code to completely lock-out a user from their machine, turning that machine into part of a botnet or other malicious purpose. Real-Time processes have the potential to completely take-over a machine. This is the number one reason Ubuntu does not carry a Real-Time kernel.


              Low-Latency Kernel


              The Low-Latency Kernel included in Ubuntu Studio (and available in the Ubuntu repositories) does not allow such malicious code from locking-out a user from their machine. It does contain other optimizations, such as Preempt-RT being enabled in the kernel configuration, to achieve the lowest possible latency for audio and other applications, while keeping the user interface usable. Latency as low as 0.1 millisecond can and has been achieved using this kernel.


              Summary


              For desktop computer usage, using a real-time kernel can cause security nightmares. The low-latency kernel included in Ubuntu Studio is completely capable of low- to no- latency while not enabling malicious processes to lock-out a user from their computer.

              Comment


              • #8
                Originally posted by Linuxxx View Post

                I'm just throwing the opinion of Ubuntu Studio's take on this here for further discussion:
                Please stop copypasting marketing mumbo jumbo. That's a lie.

                They use the Preempt-RT patch patchset if you read carefully.

                Like others, they get it for free and never contribute back or support it by funding. It's usual in Canonical parasite attitude to do that except for very few projects such as Gnome.

                Real Linux geeks into pro-audio never use Uubuntu Studio, it's a toy.

                They are a bunch of liars...

                Comment


                • #9
                  Originally posted by Linuxxx View Post

                  I'm just throwing the opinion of Ubuntu Studio's take on this here for further discussion:
                  This is wrong on so many levels, we're actually enjoying good performance and scalability today due to things merged from the RT-PATCH, and there is more things in there that fixes more issues.

                  And realtime is *predictable* nothing else - but then, just like kill -9 -1 as root will do bad things, you can do bad things with a realtime scheduler.

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                  • #10
                    Originally posted by timofonic View Post

                    Please stop copypasting marketing mumbo jumbo. That's a lie.

                    They use the Preempt-RT patch patchset if you read carefully.

                    Like others, they get it for free and never contribute back or support it by funding. It's usual in Canonical parasite attitude to do that except for very few projects such as Gnome.

                    Real Linux geeks into pro-audio never use Uubuntu Studio, it's a toy.

                    They are a bunch of liars...
                    I find it weird that they state they are using the Preempt-RT patchset, because executing "uname -a" on Ubuntu's "lowlatency" kernel shows absolutely no signs of it being an actual real-time kernel.
                    Also, this would directly contradict what they are saying about the dangers of (hard) real-time kernels, so it really doesn't make any sense at all; probably a wording oversight on their part.

                    So no, they are not being parasitic here by not contributing to the Preempt-RT initiative!

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