Collaborative Power Control = Enabled enables "pcc-cpufreq" as the "core communication" between cpufreq driver AND firmware.
https://www.kernel.org/doc/Documentation/cpu-freq/pcc-cpufreq.txt This is an interface used by HP extensively (HP servers tend to use extensively ACPI and interfaces between OS and firmware). Judging by comments on commit: https://lkml.org/lkml/2014/3/20/799 We can see that intel_pstates might actually fail to initialize cpufreq if it ever calls the cpufreq driver initialization and gets an error. We might be getting a "0" from: drivers/cpufreq/pcc-cpufreq.c -> pcc_get_freq() which is called in the code (from commit given): policy->cur = cpufreq_driver->get(policy->cpu); During the cpufreq initialization function (__cpufreq_add_dev). * This is actual the latest code in the kernel and they assume sometimes intel_pstates can fail to initialize cpufreq (even for other cpufreq drivers). If it fails it gives us that warning message pointed out. A workaround could be trying to "disable" and "enable" the core by putting it offline and online again * (Kernel code does not attempt to initialize cpufreq for a second time, for example). It looks like HP ROM engineering team might want to debug this. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1447763 Title: HP Proliant Servers suffer from cpufreq initialization failure for some cpu cores To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1447763/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
