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[Resolved] SMT not working

Posted on by vassalo27

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    • March 4, 2026 at 7:55 pm #29482
      vassalo27
      Participant

      This is my first thread in the fórum and I’ve come across an issue that I wasn’t able to solve.

      Upon booting the live image, my CPU, which is a Ryzen 7 5700X3D, only shows up to 8 threads, instead of the normal 16.

      Changing kernel parameters, forcing dracut to regenerate did nothing either, loading the module early in initramfs also did not have any effect.

      The output of cat /sys/devices/system/cpu/offline is null, meaning that the system is not even aware that there are other threads available. Also lscpu shows only one thread per core instead of two.

      I tried also with an Intel Core i5 14500 and it also display only 8 threads instead os 20. I don’t know if this is a hard limit, there are no other kernels in the repos to test.

      I thought maybe this was an issue with BIOS settings, but other live environments work just fine display all threads correctly.

    • March 4, 2026 at 11:48 pm #29483
      Silvan
      Keymaster

      Hi, thank you for reporting the problem.

      I have been wondering about this problem and now I have found that openmamba kernel has a wrong configuration which is limiting to 8 the maximum number of supported CPUs. A kernel update will be released tomorrow which fixes this limit, providing kernel support for up to 256 CPUs.

      • This reply was modified 3 days ago by Silvan.
      • This reply was modified 3 days ago by Silvan.
      • This reply was modified 3 days ago by Silvan.
    • March 5, 2026 at 12:29 am #29487
      vassalo27
      Participant

      Thanks for the reply, it makes sense. I’m looking forward for the fix.

      I liked the distribution when I tested it, but this small issue prevented me from trying it out effectively.

      Also, if I may, I would like to suggest that openmamba has a native package for fastfetch. Currently there is only neofetch. It would be a nice addition.

    • March 6, 2026 at 1:16 am #29488
      Silvan
      Keymaster

      I confirm that the kernel update with the fix (version 6.18.16-1mamba) is available for all users. The livecd snapshot generated tonight also provides the fix.

      The fastfetch package is now available in openmamba as well.

    • March 6, 2026 at 1:16 pm #29489
      vassalo27
      Participant

      Thanks for the fixes, I can confirm that too.

      Also very much appreciated that fastfetch is now available.

      Keep up the good work.

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