[vfio-users] Help Patching Qemu for Vendor

thibaut noah thibaut.noah at gmail.com
Sun May 8 21:12:37 UTC 2016


You're trying to use qemu features in libvirt xml, you cannot do that
except through command line.
What you can do quickly is creating a little bash script to replace your
qemu executable and use it for libvirt

$ cat qemu-kvm-hv-vendor
#!/bin/sh
exec PATHTOYOURQEMUKVM \
    `echo "\$@" | sed 's|hv_time|hv_time,hv_vendor_id=KeenlyKVM|g'`

$ chmod 755 qemu-kvm-hv-vendor

$ virsh edit YOURVM

Replace <emulator>PATHTOYOURQEMUKVM</emulator> with PATHTO/qemu-kvm-hv-
vendor

For more features you can replace it with this :  "
*hv_time,hv_relaxed,hv_spinlocks=0x1fff,hv_vpindex,hv_reset,hv_runtime,hv_crash,hv_vendor_id=freyja"*

*credit to alex and okky*

2016-05-08 23:08 GMT+02:00 thibaut noah <thibaut.noah at gmail.com>:

> Install qemu-git from the aur and you would have the patches with ti.
>
> You're talking about degraded performances, could you be more specific?
> I personnaly have hyper-v features and i don't see any difference
> whatsoever.
> Did you remember to modify your kernel config?
>
> 2016-05-08 22:49 GMT+02:00 Alex Williamson <alex.l.williamson at gmail.com>:
>
>> On Sun, May 8, 2016 at 2:30 PM, Spam House <kthxplzdie at gmail.com> wrote:
>>
>>> Hey All,
>>>
>>> Could anyone give me a quick summary of how to apply this (
>>> http://www.spinics.net/lists/kvm/msg121742.html) patch to Qemu on Arch
>>> Linux.
>>>
>>> I've cloned the Qemu git and have tried various ways of parsing the info
>>> in the link into other files and using 'ed' to try and append/update the
>>> files with no success.
>>>
>>> Example:
>>> git clone qemu
>>> cd qemu/target-i386
>>> nano cpu-qom.b (insert diff changes and save add 'w' at the very end)
>>> ed - cpu-qom.h < cpu-qom.b
>>>
>>> ed returns ? and deletes/blanks out cpu-qom.h
>>>
>>> Complete noob any help appreciated!
>>>
>>> I do have a windows10 vm with my 980ti passthrough running successfully.
>>> The performance has degraded since switching from Unraid to Arch and the
>>> only difference I can find is HyperV related. It seems this is the last
>>> hurtle.
>>>
>>
>> This has been in QEMU since the 2.5 release, if you're cloning qemu.git,
>> the change is already there.  Surely Arch has QEMU builds including it as
>> well.
>>
>> _______________________________________________
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>> vfio-users at redhat.com
>> https://www.redhat.com/mailman/listinfo/vfio-users
>>
>>
>
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