| 2024-03-04 10:38:35 |
You-Sheng Yang |
description |
[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-calderon@linux.intel.com/
[Business Justification]
[Testing guidance]
[External ID]
LFE-6901 |
[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-calderon@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-calderon@linux.intel.com/
[Business Justification]
[Testing guidance]
[External ID]
LFE-6901 |
|
