Backend memory object creation - query

Peter Krempa pkrempa at
Thu Jan 27 10:07:13 UTC 2022

On Thu, Jan 27, 2022 at 04:05:19 +0000, M, Shivakumar wrote:
> Hello,


note that there's no need to CC both libvir-list and libvirt-users
maling lists.

> For our use-case with Libvirt we want to create the Memory backend object ,
> Expected QEMU args would be
> -object memory-backend-memfd,id=mem1,size=4096M

Your description is a bit vague. Do you want to use it to back the guest

As by itself a memory object itself is useless without being attached

In case you want to configure qemu to back the default memory of the VM
by a memfd:


<domain type='kvm'>

   <source type='memfd'/>

Results into invoking qemu with:

-machine pc-i440fx-2.9,usb=off,vmport=off,dump-guest-core=off,memory-backend=pc.ram \
-object '{"qom-type":"memory-backend-memfd","id":"pc.ram","x-use-canonical-path-for-ramblock-id":false,"size":1048576000,"host-nodes":[0],"policy":"bind"}' \

> Request you to please help us to specify this arg in the libvirt XML.
> Thanks,
> Shiv

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