4 ms·

The linux kernel is tuned for throughput, not latency and certainly not bounded-latency. My background is industrial/defense/medical s/w on hard real time syst

The linux kernel is tuned for throughput, not latency and certainly not bounded-latency. My background is industrial/defense/medical s/w on hard real time systems. e.g. I've worked on train braking systems, high throughput radar systems, medical devices, lots hard real-time control stuff.... I personally have never seen any evidence of anything greater than SIL-2 certified Linux (https://www.osadl.org/SIL2LinuxMP.sil2-linux-project.0.html https://www.osadl.org/SIL2LinuxMP.sil2-linux-project.0.html) and that is only in very narrowly defined context. Like I said earlier, any higher certification, Linux would be run as a comparmentalised, lower-level subsystem. The real control would not be via a Linux controlled task. Until you can point me to the test-suite for a Linux kernel& driver set that gives me 100% code-coverage, then Linux will never get past this point. Dont get me wrong, I like Linux and it has a valuable place in embedded systems.... but hard-real-time control and safety-related systems is not it. As a final word on the subject, dont take my word for it: http://www.hse.gov.uk/research/rrhtm/rr011.htm http://www.hse.gov.uk/research/rrhtm/rr011.htm "it is not likely to be either suitable or certifiable for SIL 4 applications" "It is unlikely that Linux would be useful for SIL 4 applications and it would not be reasonably practicable to provide evidence that it meets a SIL 4 integrity requirement. " ...And in (https://www.osadl.org/fileadmin/dam/presentations/61508/61508_paper.pdf https://www.osadl.org/fileadmin/dam/presentations/61508/6150...) "One of the main conclusion: Linux is not suitable for SIL4."

fit2rule 11y ago
>Until you can point me to the test-suite for a Linux kernel& driver set that gives me 100% code-coverage, then Linux will never get past this point. Of course, this is proprietary to the whims of the companys' deploying SIL-4 Linux: THALES, et al. http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2011/hwsw-codesign-student-presentations/gv1-thales http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2... http://ercim-news.ercim.eu/en75/special/tas-control-platform-a-platform-for-safety-critical-railway-applications http://ercim-news.ercim.eu/en75/special/tas-control-platform... http://www.ibm.com/developerworks/library/l-real-time-linux/ http://www.ibm.com/developerworks/library/l-real-time-linux/ (BTW, HSE isn't exactly an industrial authority on much ..)
- TickleSteve 11y ago
  > Of course, this is proprietary to the whims of the companys' deploying SIL-4 Linux: THALES, et al. I've worked with Thales companies many times in the past. Never seen any evidence of Sil4 Linux. And no, this is absolutely not at the whim of the companies deploying it. >http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2.. http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2.... No mention of Linux. > http://ercim-news.ercim.eu/en75/special/tas-control-platform.. http://ercim-news.ercim.eu/en75/special/tas-control-platform.... 1 mention of Linux... no mention of the role it plays. >http://www.ibm.com/developerworks/library/l-real-time-linux/ http://www.ibm.com/developerworks/library/l-real-time-linux/ Verifies my point. Only the kernel-in-kernel/hypervisor systems get hard-real-time performance. This is necessary for safety-critical work. > (BTW, HSE isn't exactly an industrial authority on much ..) HSE == Health & Safety Executive... they are very much involved in this.... they're the government authority related to this type of stuff. They license software for use in Nuclear Reactors and the like (along with other agencies). My points absolutely still stand.
  - fit2rule 11y ago
    Hint: I was on the team that released TAS PLF 2.x, and it is definitely SIL4, definitely hard real-time, and definitely a well-maintained Linux project which many other divisions (i.e. Space) also come to use as a reference platform. I suggest you simply missed it: its running an awful lot of rail transportation systems around the world, though...
    - TickleSteve 11y ago
      Hint: you're mistaken at the role Linux played in it. Go study your architecture diagrams. The system as a whole is SIL-4, thats not the argument. Linux certainly isn't, that I can guarantee. The work to provide full traceability trees and 100% coverage thru the Linux kernel is many man-centuries of work. That has not been done. The SIL rated side will be a different kernel/hypervisor. If what you're talking about involves RedHat MRG, then that product has a completely different kernel. Its not standard linux.

fit2rule 11y ago

>Until you can point me to the test-suite for a Linux kernel& driver set that gives me 100% code-coverage, then Linux will never get past this point. Of course, this is proprietary to the whims of the companys' deploying SIL-4 Linux: THALES, et al. http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2011/hwsw-codesign-student-presentations/gv1-thales http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2... http://ercim-news.ercim.eu/en75/special/tas-control-platform-a-platform-for-safety-critical-railway-applications http://ercim-news.ercim.eu/en75/special/tas-control-platform... http://www.ibm.com/developerworks/library/l-real-time-linux/ http://www.ibm.com/developerworks/library/l-real-time-linux/ (BTW, HSE isn't exactly an industrial authority on much ..)

TickleSteve 11y ago
> Of course, this is proprietary to the whims of the companys' deploying SIL-4 Linux: THALES, et al. I've worked with Thales companies many times in the past. Never seen any evidence of Sil4 Linux. And no, this is absolutely not at the whim of the companies deploying it. >http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2.. http://ti.tuwien.ac.at/ecs/teaching/courses/hwswcode_vu_WS_2.... No mention of Linux. > http://ercim-news.ercim.eu/en75/special/tas-control-platform.. http://ercim-news.ercim.eu/en75/special/tas-control-platform.... 1 mention of Linux... no mention of the role it plays. >http://www.ibm.com/developerworks/library/l-real-time-linux/ http://www.ibm.com/developerworks/library/l-real-time-linux/ Verifies my point. Only the kernel-in-kernel/hypervisor systems get hard-real-time performance. This is necessary for safety-critical work. > (BTW, HSE isn't exactly an industrial authority on much ..) HSE == Health & Safety Executive... they are very much involved in this.... they're the government authority related to this type of stuff. They license software for use in Nuclear Reactors and the like (along with other agencies). My points absolutely still stand.
- fit2rule 11y ago
  Hint: I was on the team that released TAS PLF 2.x, and it is definitely SIL4, definitely hard real-time, and definitely a well-maintained Linux project which many other divisions (i.e. Space) also come to use as a reference platform. I suggest you simply missed it: its running an awful lot of rail transportation systems around the world, though...
  - TickleSteve 11y ago
    Hint: you're mistaken at the role Linux played in it. Go study your architecture diagrams. The system as a whole is SIL-4, thats not the argument. Linux certainly isn't, that I can guarantee. The work to provide full traceability trees and 100% coverage thru the Linux kernel is many man-centuries of work. That has not been done. The SIL rated side will be a different kernel/hypervisor. If what you're talking about involves RedHat MRG, then that product has a completely different kernel. Its not standard linux.