SRU: * https://lists.ubuntu.com/archives/kernel-team/2024-March/149332.html (noble) * https://kernel.ubuntu.com/gitea/kernel/noble-linux-unstable/src/branch/vicamo/bug-2049793-mtl-sysfs-cacheinfo (unstable, to create pull request once branch sync is done)
** Description changed: + [SRU Justification] + + [Impact] + + The interface /sys/devices/system/cpu/cpuX/cache is broken (not populated) if + CPUs have different numbers of subleaves in CPUID 4. This is the case of Intel + Meteor Lake. + + [Fix] + + https://lore.kernel.org/all/20231212222519.12834-1-ricardo.neri-calde...@linux.intel.com/ + Reviewed, but probably will only land in v6.9. + + [Test Case] + + Check existence of cpu cache info: + + $ ls /sys/devices/system/cpu/cpu0/cache/ + index0 index1 index2 index3 uevent + + [Where problems could occur] + + This populates sysfs entries that should have been available, not + something new or alters existing interface. + + [Other Info] + + While this is targets v6.8 for Intel LPMD (Low Power Model Daemon)'s + use, only Noble and Unstable will be nominated for fix. + + ========== original bug report ========== + [Description] - The interface /sys/devices/system/cpu/cpu*/cache is empty. In Meteorlake, not all CPUs have the same number of subleaves in the CPUID 4 leaf. The compute die CPUs have 3 subleaves whereas the CPUs in the SoC die have 2. This problem happens because Linux assumes that all CPUs have the same number of subleaves. + The interface /sys/devices/system/cpu/cpu*/cache is empty. In Meteorlake, not all CPUs have the same number of subleaves in the CPUID 4 leaf. The compute die CPUs have 3 subleaves whereas the CPUs in the SoC die have 2. This problem happens because Linux assumes that all CPUs have the same number of subleaves. [Hardware Information] - Architecture: - Intel / AMD (x86_64) - Platform(s): - Meteor Lake - Date HW is expected at Canonical: - - Component(s): - x86 + Architecture: + Intel / AMD (x86_64) + Platform(s): + Meteor Lake + Date HW is expected at Canonical: + + Component(s): + x86 [Software Information] - Target Version: - 24.04 - Target Kernel: - 6.8 - Commit IDs: - TBD - External Links: - https://lore.kernel.org/all/20231212222519.12834-5-ricardo.neri-calde...@linux.intel.com/ + Target Version: + 24.04 + Target Kernel: + 6.8 + Commit IDs: + TBD + External Links: + https://lore.kernel.org/all/20231212222519.12834-5-ricardo.neri-calde...@linux.intel.com/ [Business Justification] - [Testing guidance] - [External ID] - LFE-6901 + LFE-6901 -- 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/2049793 Title: [MTL] x86: Fix Cache info sysfs is not populated Status in intel: New Status in linux package in Ubuntu: In Progress Status in linux source package in Noble: In Progress Bug description: [SRU Justification] [Impact] The interface /sys/devices/system/cpu/cpuX/cache is broken (not populated) if CPUs have different numbers of subleaves in CPUID 4. This is the case of Intel Meteor Lake. [Fix] https://lore.kernel.org/all/20231212222519.12834-1-ricardo.neri-calde...@linux.intel.com/ Reviewed, but probably will only land in v6.9. [Test Case] Check existence of cpu cache info: $ ls /sys/devices/system/cpu/cpu0/cache/ index0 index1 index2 index3 uevent [Where problems could occur] This populates sysfs entries that should have been available, not something new or alters existing interface. [Other Info] While this is targets v6.8 for Intel LPMD (Low Power Model Daemon)'s use, only Noble and Unstable will be nominated for fix. ========== original bug report ========== [Description] The interface /sys/devices/system/cpu/cpu*/cache is empty. In Meteorlake, not all CPUs have the same number of subleaves in the CPUID 4 leaf. The compute die CPUs have 3 subleaves whereas the CPUs in the SoC die have 2. This problem happens because Linux assumes that all CPUs have the same number of subleaves. [Hardware Information] Architecture: Intel / AMD (x86_64) Platform(s): Meteor Lake Date HW is expected at Canonical: Component(s): x86 [Software Information] Target Version: 24.04 Target Kernel: 6.8 Commit IDs: TBD External Links: https://lore.kernel.org/all/20231212222519.12834-5-ricardo.neri-calde...@linux.intel.com/ [Business Justification] [Testing guidance] [External ID] LFE-6901 To manage notifications about this bug go to: https://bugs.launchpad.net/intel/+bug/2049793/+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
