<html><head></head><body><div style="font-family: Verdana;font-size: 12.0px;"><div>Greetings,<br/>
<br/>
passthrough means you pass the device as is with minimal or no change at all.</div>
<div>for example, if you passthrough a pci device, the pci address might change but the rest won't.</div>
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<div>hope this helps</div>
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<div>Dagg</div>
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<div style="margin:0 0 10px 0;"><b>Sent:</b> Sunday, November 14, 2021 at 11:52 PM<br/>
<b>From:</b> "Toolybird" <toolybird@tuta.io><br/>
<b>To:</b> "Libvirt Users" <libvirt-users@redhat.com><br/>
<b>Subject:</b> CPU vendor_id handling</div>
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<div>Hello,</div>
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<div>There are times when spoofing the CPU vendor_id is convenient. For example, some x86 guest OS's only run on Intel and refuse to run on an AMD host. Libvirt does support this in the "host-model" case, but it doesn't work for CPU "host-passthrough". On the QEMU command line it's as easy as:</div>
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<div>$ qemu-system-x86_64 -cpu host,vendor=GenuineIntel</div>
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<div>This works fine in libvirt XML:</div>
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<div><cpu mode='host-model'></div>
<div> <model vendor_id='GenuineIntel'/></div>
<div></cpu></div>
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<div>This doesn't:</div>
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<div><cpu mode='host-passthrough'></div>
<div> <model vendor_id='GenuineIntel'/></div>
<div></cpu></div>
<div> </div>
<div>Libvirt silently strips out the model line after saving "virsh edit ..."</div>
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<div>Is there any reason why libvirt cannot support this in the host-passthrough case? The status quo means that some folks end up resorting to <qemu:arg value='-cpu'/> hacks which of course causes all sorts of confusion with multiple -cpu lines getting passed to QEMU.</div>
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<div>Thanks</div>
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