[Bug 2126577] Re: [26.04 FEAT] Set Architecture Level (ALS) to z15

Frank Heimes 2126577 at bugs.launchpad.net
Thu Oct 30 10:53:57 UTC 2025


** Changed in: ubuntu-z-systems
       Status: In Progress => Fix Committed

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https://bugs.launchpad.net/bugs/2126577

Title:
  [26.04 FEAT] Set Architecture Level (ALS) to z15

Status in Ubuntu on IBM z Systems:
  Fix Committed
Status in gcc-15 package in Ubuntu:
  Fix Released
Status in linux package in Ubuntu:
  Fix Committed
Status in llvm-toolchain-20 package in Ubuntu:
  Fix Released
Status in llvm-toolchain-21 package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader package in Ubuntu:
  New

Bug description:
  The IBM Z team requests to raise the architectural level set (ALS) for Ubuntu on IBM Z and LinuxONE (s390x) to z15, optimized for z16.
  For the gcc-15 compiler (and with that for user space) that would be in debian/rules2:
  march=z15
  mtune=z16

  For the kernel that would be:
  debian.master/config/annotations
   CONFIG_MARCH_Z15                                policy<{'s390x': 'y'}>
   CONFIG_TUNE_Z16                                 policy<{'s390x': 'y'}>

  (I am not sure yet, but assume that gcc-15 will still be the default
  also in 26.04.)

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