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POWER Updates For Linux 4.17 Drop POWER4 CPU Support

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  • POWER Updates For Linux 4.17 Drop POWER4 CPU Support

    Phoronix: POWER Updates For Linux 4.17 Drop POWER4 CPU Support

    In addition to Linux 4.17 dropping eight obsolete CPU architectures, this next kernel release is also doing away with POWER4 CPU support...

    http://www.phoronix.com/scan.php?pag...x-4.17-Updates

  • #2
    This is akin to dropping Pentium III or P4 support ... these machines topped out at 1.9Ghz... so it isn't quite like they are dropping ancient sub 100Mhz machines.

    As far as longevity dropping support for a machine that could have been bought 13 years ago is pretty quick. Also this probably means G5 support is being dropped as it is the same architecture just by another name.
    Last edited by cb88; 04-07-2018, 04:38 PM.

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    • #3
      Originally posted by cb88 View Post
      This is akin to dropping Pentium III or P4 support ...
      Not quite, that was first multi-core processor.

      http://www-03.ibm.com/ibm/history/ib.../icons/power4/

      So that should be like Intel droping their first multi-core.

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      • #4
        [QUOTE=phoronix;n1017633]Phoronix: POWER Updates For Linux 4.17 Drop POWER4 CPU Support

        In addition to Linux 4.17 dropping eight obsolete CPU architectures, this next kernel release is also doing away with POWER4 CPU support...

        http://<a href="http://www.phoronix..../a>&#91;/QUOTE]

        Michael,

        Can you please point to your source?

        I see no such change at https://git.kernel.org/pub/scm/linux...rpc/linux.git/

        I suspect that the actual change has been to drop support for IBM POWER4 boxes, and NOT the general support for PowerPC 970 CPUs. The latter are used in the Apple PowerMac G5 and iMac G5 systems and have a relatively small (vs i686/X86_64) but very active number of developers. This is a common area of confusion, as the general gcc option for the whole family of CPUs that includes the latter is -mpower4 (and binutils assembler machine type POWER4).

        I am also curious as to whether IBM POWER4+ systems are affected.
        Al
        Last edited by AlDunsmuir; 04-07-2018, 05:39 PM.

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        • #5
          [QUOTE=AlDunsmuir;n1017644]
          Originally posted by phoronix View Post
          Phoronix: POWER Updates For Linux 4.17 Drop POWER4 CPU Support

          In addition to Linux 4.17 dropping eight obsolete CPU architectures, this next kernel release is also doing away with POWER4 CPU support...

          http://<a href="http://www.phoronix..../a>&#91;/QUOTE]

          Michael,

          Can you please point to your source?

          I see no such change at https://git.kernel.org/pub/scm/linux...rpc/linux.git/

          I suspect that the actual change has been to drop support for IBM POWER4 boxes, and NOT the general support for PowerPC 970 CPUs. The latter are used in the Apple PowerMac G5 and iMac G5 systems and have a relatively small (vs i686/X86_64) but very active number of developers. This is a common area of confusion, as the general gcc option that includes the latter is -.

          I am also curious as to whether IBM POWER4+ systems are affected.
          Al
          From the linked PR....

          "- Removal of POWER4 support, which was accidentally broken in 2016 and no one noticed, and blocked use of some modern instructions."
          Michael Larabel
          http://www.michaellarabel.com/

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          • #6
            Erm... I had not the impression that POWER4 support was broken since 2016? Been building and running kernels on two PowerMac G5 since that time.

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            • #7
              Originally posted by Michael View Post

              From the linked PR....

              "- Removal of POWER4 support, which was accidentally broken in 2016 and no one noticed, and blocked use of some modern instructions."
              Tomorrow will be "ditch POWER5 and POWER6 because these are not secure"

              Consistent with previously announced end of service, IBM will not be releasing patches for POWER4, POWER5, POWER6 systems and recommends migrating to a more current generation of POWER technology.
              https://www.ibm.com/blogs/psirt/pote...-power-family/

              So, 4/5/6 are in "who cares" support mode anway
              Last edited by dungeon; 04-07-2018, 06:33 PM.

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              • #8
                what about SSE involvement? Kernel and operating systems are able to take benefit from SSE and other cpu's instructions?

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                • #9
                  Michael,

                  I found the exact patch at patchwork.ozlabs.org via a quick Google search.
                  - It removes support for a generic POWER4 CPU family, which does remove support for IBM POWER4 and POWER4+ servers.
                  - Note that there were already separate categories for PPC970 (the CPU used in Apple G5 systems) and POWER5, and these are still actively maintained.

                  I'm mildly unhappy that my IBM 7028-6C4 4-way box (POWER4+) won't be supported by 4.17+, but as a CHRP box it already had issues booting Linux because it couldn't handle the larger initramfs sizes.

                  Al

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                  • #10
                    In the 2000th we where proud Linux would run on everything and the fridge or microwave. Now people are proud when support for nice retro / vintage systems is deleted? sad.

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