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+++ This bug was initially created as a clone of Bug #770122 +++ Description of problem: max_cstate=1 was added to kernel defaults for oVirt Node due to a large portion of hardware having issues w/ time sync in kvm. As long as hardware has a stable/constant tsc, it should be safe to remove this restriction. People with older hardware can always manually add it back in.
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor to limit clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.
Technical note updated. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. Diffed Contents: @@ -1 +1 @@ -Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor to limit clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.+Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.
Technical note updated. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. Diffed Contents: @@ -1 +1 @@ -Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on hardware where clock skew issues are anticipated.+Previously the Hypervisor always included 'max_cstate=1' in the kernel boot options. This limited the cstates available to the processor, avoiding clock skew on older hardware. The Hypervisor has been updated and this option is now only used on older hardware where clock skew issues are anticipated. On newer hardware where this is not an issue all supported cstates are available.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2012-0741.html