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  • Raising the minimum required s390x CPU to z196?

    From Aurelien Jarno@21:1/5 to All on Wed Jan 31 15:40:01 2018
    Hi all,

    The Debian s390x port currently officially defaults to the z900 ISA.
    That's what our GCC defaults too, but I wouldn't be surprised if a few
    packages use a slightly newer ISA.

    Unfortunately more and more packages require a newer ISA, usually at
    least z196. This is the case of at least nodejs, go and rustc. It should
    be noted that it's not a question of passing the right flag to GCC, but
    rather these packages have their own JIT compiler which has been written
    for a z196 ISA minimum.

    For go we currently use gccgo instead of golang, which is not really
    an optimal solution and prevents many packages to build. For the same
    reason rustc is not available on s390x, which might become problematic
    soon (for example rsvg will require it soon). Finally recent versions
    of nodejs require at least a z196 CPU, so we have to drop all nodejs
    packages if we want to keep the baseline as z900.

    In my opinion we don't really have any other choice than raising the
    minimum ISA to z196, even if this CPU is less than 7 years old. The
    the only other alternative I can think about would be to have people
    committing to maintain patches lowering the minimum ISA for the above
    packages. I started to work on that for go a few months ago, but
    unfortunately that's a huge work as upstream keeps moving.

    The ISA change would be done in testing/unstable and released for
    Buster. Stretch would be unchanged in that regard and it will continue
    to be supported for 2 more years.

    Note also that it means that we would have to get rid of our older
    build daemon, zemlinsky.d.o. We would still have 2 buildd daemons in 2 different locations left, which is enough to run the port. However that
    would be appreciable to get a third one to fully secure the port.

    Any opinion, or alternative solution?

    Thanks,
    Aurelien

    --
    Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net

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  • From Aurelien Jarno@21:1/5 to Aurelien Jarno on Tue Feb 6 21:10:01 2018
    On 2018-01-31 15:38, Aurelien Jarno wrote:
    Hi all,

    The Debian s390x port currently officially defaults to the z900 ISA.
    That's what our GCC defaults too, but I wouldn't be surprised if a few packages use a slightly newer ISA.

    Unfortunately more and more packages require a newer ISA, usually at
    least z196. This is the case of at least nodejs, go and rustc. It should
    be noted that it's not a question of passing the right flag to GCC, but rather these packages have their own JIT compiler which has been written
    for a z196 ISA minimum.

    For go we currently use gccgo instead of golang, which is not really
    an optimal solution and prevents many packages to build. For the same
    reason rustc is not available on s390x, which might become problematic
    soon (for example rsvg will require it soon). Finally recent versions
    of nodejs require at least a z196 CPU, so we have to drop all nodejs
    packages if we want to keep the baseline as z900.

    In my opinion we don't really have any other choice than raising the
    minimum ISA to z196, even if this CPU is less than 7 years old. The
    the only other alternative I can think about would be to have people committing to maintain patches lowering the minimum ISA for the above packages. I started to work on that for go a few months ago, but unfortunately that's a huge work as upstream keeps moving.

    Note that both hercules and QEMU are able to simulate a z196 CPU, or at
    least the facilities used by the Linux kernel and user land when built
    for z196.

    Aurelien

    --
    Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@aurel32.net http://www.aurel32.net

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