Red Hat Bugzilla – Bug 150893
On few Nocona based platforms, acpi-cpufreq driver assumes the wrong CPU freq at boot time
Last modified: 2007-11-30 17:07:16 EST
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Description of problem:
This bug was uncovered on a Nocona based platform, that supports Enhanced
Speedstep (EST), has 3 possible frequencies (3.6, 3.2 and 2.8 GHz). But, at
the boot time system comes up with 2.8 GHz. In this case, acpi-cpufreq wrongly
assumes that CPU is running at maximum (3.6 GHz) speed. And when there are no
cpufreq governors running (either userspace or ondemand), the CPUs keep
running at the lowest freq, while OS reports that it is running at the highest
Attached patch fixes the issue. A similar patch has also been sent to upstream
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Enable GV3 in BIOS
2. Disable cpufreq daemon
3. Reboot the system
Actual Results: On this particular system, it is running at 2.8 GHz, but kernel reports 3.6 under sysfs
Expected Results: Kernel should report 2.8 GHz
Created attachment 111901 [details]
This bug is there in both i386 and x86-64 kernels.
Attached patch fixes the bug in both kernels.
Created attachment 115937 [details]
The wrong version of the patch was posted, this one is correct.
I will reverify with the latest code and post it for inclusion in U3.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.