[Bug 2164516] Re: [UBUNTU 22.04] s390/topology: Use zero-based numbering

Thanks for reporting. Patch sent to KTML: https://lists.ubuntu.com/archives/kernel-team/2026-August/171074.html ** Changed in: linux (Ubuntu Jammy) Status: New => In Progress ** Changed in: linux (Ubuntu Noble) Status: New => In Progress ** Changed in: linux (Ubuntu Resolute) Status: New => In Progress ** Changed in: ubuntu-z-systems Status: Triaged => In Progress -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2164516 Title: [UBUNTU 22.04] s390/topology: Use zero-based numbering Status in Linux: Triaged Status in Ubuntu on IBM z Systems: In Progress Status in linux package in Ubuntu: Invalid Status in linux source package in Jammy: In Progress Status in linux source package in Noble: In Progress Status in linux source package in Resolute: In Progress Bug description: [Impact] s390/topology: Use zero-based numbering for containing entities Start the numbering scheme for higher-level topology structures (like socket, book, drawer) at zero, matching the convention for other hardware identifiers like e.g. CPU numbers. Hardware documentation, the Hardware Management Console and other tools like zmemtopo also use zero-based numbering for these containing entities. Aligning the numbering in sysfs, procfs, and tools like lscpu improves user experience by making it easier to correlate topology information across different interfaces. If available, Linux on s390 derives this physical topology information from the stsi function code 15 store_topology instruction, which is defined to start at 1 for the lowest numbered container id. Subtract one, so drawer_id, book_id and socket_id in cpu_topology[] start with 0 for the lowest numbered entity; and /proc/cpuinfo and tools like 'lscpu -ye' display the expected values. Display only, no functional change intended. [Fix] Cherry pick commit: - 540f4a4f6ef8 ("s390/topology: Use zero-based numbering for containing entities") [Test Plan] Run 'lscpu -ye' to make sure that zero-based numbering is used for socket, book, drawer, etc. [Regression Potential] No functional change intended. Regression potential is very low. --- Description: s390/topology: Use zero-based numbering Symptom: Ids displayed by 'lscpu -ye' don't match HW Ids Problem: Hardware documentation, the Hardware Management Console and other tools like zmemtopo use zero-based numbering for socket, book, drawer. But the linux kernel displays one-based numbering in sysfs, procfs and lscpu. Reproduction: 'lscpu -ye' Affected Distros: Ubuntu 22.04, 24.04, 26.04 Solution: Correct the indices the kernel gets from HW sysinfo. Upstream-ID: 540f4a4f6ef806a28e794001bb4beac4840a6090 To manage notifications about this bug go to: https://bugs.launchpad.net/linux/+bug/2164516/+subscriptions