Bug 825400

Summary: Hyperthreading not working on i7-3770S
Product: [Fedora] Fedora Reporter: Kevin Clevenger <kcleveng>
Component: kernelAssignee: Kernel Maintainer List <kernel-maint>
Status: CLOSED NOTABUG QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: high Docs Contact:
Priority: unspecified    
Version: 17CC: gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda
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Target Release: ---   
Hardware: x86_64   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2012-05-29 14:22:49 UTC Type: Bug
Regression: --- Mount Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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sosreport none

Description Kevin Clevenger 2012-05-25 23:01:40 UTC
Created attachment 586965 [details]
sosreport

Description of problem:
F17 with current updates on a Biostar TZ77B with an i7-3770S shows only 4 cores. 

Version-Release number of selected component (if applicable):
3.3.7-1.fc17.x86_64

How reproducible:
Boot and check /proc/cpuinfo

Steps to Reproduce:
1. N/A
2.
3.

Actual results:
CPU's 0-3 are available

Expected results:
CPU's 0-7 should be available

Additional info:
I have tested the identical setup and BIOS settings with another distro and hyperthreading works correctly when running it.

Comment 1 Dave Jones 2012-05-27 21:19:42 UTC
you booted with acpi=off, forcing the kernel to fall back to using the legacy MPS method of cpu enumeration, which it seems is broken on your BIOS.

Turn acpi back on, and it should be fine.