Due to a bug in gcc-9 (default version) packaging, it has been configured in focal with both march & mtune set to z13.
And gcc-9 will remain configured this way in focal (20.04). At this point we don't have enough time for a full archive rebuild with mtune set to z15, and majority of distribution binaries will not be rebuild at this point and are final. Meaning an update to z15 will only have impact on security & SRU packages. Changing mtune in all focal SRUs & security updates increases risk of any update regressing or failing to build from source. We can SRU individual packages to build with mtune z15 if there is significant performance improvement from doing so. Linux Kernel & atlas are correctly built with mtune z15 in focal. focal (20.04) will have non-default gcc-10 updated to use march z13 & mtune z15. GG-series (20.10) will have the default gcc version updated to use march z13 & mtune z15. ** Also affects: gcc-10 (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1837525 Title: [20.04 FEAT] Set Architecture Level (ALS) to z13 Status in Ubuntu on IBM z Systems: Fix Released Status in atlas package in Ubuntu: Fix Released Status in gcc-10 package in Ubuntu: New Status in gcc-9 package in Ubuntu: Fix Released Status in linux package in Ubuntu: Fix Released Bug description: IBM requests to update the Architecture Level Set (ALS) as follow.. march=z13 mtune=z15 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu-z-systems/+bug/1837525/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp