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+++ This bug was initially created as a clone of Bug #799354 +++
Would be handy to have <cpu mode='host-model'> support <feature policy='force'/> or policy=disable. That way tools have an option to turn on x2apic for kvm guests which provides a performance boost with no downsides, but doesn't require host CPU support.
--- Additional comment from rjones on 2012-10-25 14:05:16 EDT ---
Also <feature policy='disable'/>. For one use case, see:
https://bugzilla.redhat.com/show_bug.cgi?id=870071#c2
Fixed upstream with:
commit 3c8be55c04eb2647fd5c9d51efae78f7afdcec85
Author: Peter Krempa <pkrempa>
Date: Mon Jul 15 17:38:55 2013 +0200
cpu: Allow fine tuning of "host-model" cpu
https://bugzilla.redhat.com/show_bug.cgi?id=799354
Until now, the "host-model" cpu mode couldn't be influenced. This patch
allows to use the <feature> elements to either enable or disable
specific CPU flags. This can be used to force flags that can be emulated
even if the host CPU doesn't support them.
commit 13cdd389ed06e81277f208c269d825046cdbb4cb
Author: Peter Krempa <pkrempa>
Date: Mon Jul 15 14:36:09 2013 +0200
cpu: Add virCPUDefUpdateFeature()
This new function updates or adds a feature to a existing cpu model
definition. This function will be helpful to allow tuning of
"host-model" features in later patches.
v1.1.0-193-g3c8be55
This bug has already been fixed upstream but it is considered
unsuitable for backporting to RHEL 6.5 because at least one of the
following conditions is met:
- the patches required to address this bug are complex or invasive
causing the backport to be too risky
- this bug is not important enough to justify backporting non-trivial
patches for it
Thus I'm pushing this bug to RHEL 6.6 (and setting Upstream keyword to
indicate we have patches upstream) for now. If you don't agree with
this resolution, please, give us reasons which you think are strong
enough for us to reevaluate the decision not to backport patches for
this bug.
Comment 7RHEL Program Management
2014-04-04 21:00:13 UTC
Development Management has reviewed and declined this request.
You may appeal this decision by reopening this request.