[pve-devel] [PATCH] add win81 ostype and use qemu64 cpumodel if kvm64 is defined
Alexandre DERUMIER
aderumier at odiso.com
Wed Nov 27 08:51:22 CET 2013
in libvirt: src/cpu/cpu_map.xml
they a are a cpu list definition, with standard cpu but also custom cpu
...
<model name='cpu64-rhel6'>
<model name='cpu64-rhel5'/>
<feature name='cx16'/>
<feature name='lahf_lm'/>
</model>
--> this one is the default used by rhev, they have enabled the lahf_lm flag
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Host_Configuration_and_Guest_Installation_Guide/ch03s02.html
Rhev don't support qemu64 or kvm64 cpu type, but only their own custom cpu definition
another interesting note, why kvm64 model have less flags than qemu64:
<model name='qemu64'>
<model name='kvm64'/>
<!-- These are supported only by TCG. KVM supports them only if the
host does. So we leave them out:
<feature name='popcnt'/>
<feature name='lahf_lm'/>
<feature name='sse4a'/>
<feature name='abm'/>
-->
<feature name='svm'/>
</model>
according to :
http://en.wikipedia.org/wiki/SSE4
sse4a : These instructions are not available in Intel processors.
popcnt: Intel implements POPCNT beginning with the Nehalem microarchitecture.AMD calls this pair of instructions Advanced Bit Manipulation (ABM).
abm: same thatn popcnt, but amd only
so theses 3flags make sense
but lahf_lm is supported by amd and intel since a long time.
Don't known why they remove it
----- Mail original -----
De: "Alexandre DERUMIER" <aderumier at odiso.com>
À: "Dietmar Maurer" <dietmar at proxmox.com>
Cc: pve-devel at pve.proxmox.com
Envoyé: Mercredi 27 Novembre 2013 08:22:39
Objet: Re: [pve-devel] [PATCH] add win81 ostype and use qemu64 cpumodel if kvm64 is defined
>>How does libvirt handle that?
AFAIK, libvirt don't choose for you the best cpu type for a specific os.
But maybe ovirt,rhev,openstack are doing it in their code.
I'll try to have a look at them.
----- Mail original -----
De: "Dietmar Maurer" <dietmar at proxmox.com>
À: "Alexandre Derumier" <aderumier at odiso.com>, pve-devel at pve.proxmox.com
Envoyé: Mercredi 27 Novembre 2013 06:54:18
Objet: RE: [pve-devel] [PATCH] add win81 ostype and use qemu64 cpumodel if kvm64 is defined
How does libvirt handle that?
> see
> http://forum.proxmox.com/threads/16206-Windows-Server-2012-R2-and-
> 0x0000005D-Error
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