Qemu-system-x86_64 Does Not Support Fw_cfg Option
Hi
I am trying to run CoreOS (Container Linux) as a guest OS using KVM/QEMU. One of their suggestions is to pass config info into the VM
using the “fw_cfg” option . When I try this I get the error “-fw_cfg invalid option”. If I run the vm with the help option it does not list the fw_cfg option. However, according to the qemu documentation, see here
The command used to run the vm is:
/usr/bin/qemu-system-x86_64 -name CL-IGN-1 -m 1024 \
-net nic,vlan=0,model=virtio \
-net user,vlan=0,hostfwd=tcp::2222-:22,hostname=CL-IGN-1 \
-drive if=virtio,file=./coreos_production_qemu_image.img \
-fw_cfg name=opt/com.coreos/config,file=./CL-IGN-1.ignconfig
qemu-system-x86_64: -fw_cfg: invalid option
I also tried using /usr/libexec/qemu-kvm but got the same error.
I am running::
CentOS Linux release 7.3.1611 (Core)
qemu-system-x86-2.0.0-1.el7.6.x86_64
qemu-kvm-1.5.3-126.el7.x86_64
Thanks.
2 thoughts on - Qemu-system-x86_64 Does Not Support Fw_cfg Option
Hello, I think (based also on your qemu-kvm version man page), that the feature is not present in qemu-kvm version provided by base CentOS. But you can use packages provided by the Virtualization SIG
Good idea especially if virtualization is core service for your server. See here the announcement:
https://lists.CentOS.org/pipermail/CentOS-announce/2015-October/021445.html
So you can follow what detailed there:
yum install CentOS-release-qemu-ev yum install qemu-kvm-ev
I reproduced a situation on a CentOS 7.3 server where qemu-kvm is already present and you can do
yum install CentOS-release-qemu-ev
and then
yum update qemu-kvm-ev
… Dependencies Resolved
=================================================================================================== Package Arch Version Repository Size
===================================================================================================Installing:
qemu-img-ev x86_64 10:2.6.0-28.el7.10.1
CentOS-qemu-ev 1.0 M
replacing qemu-img.x86_64 10:1.5.3-126.el7_3.10
qemu-kvm-common-ev x86_64 10:2.6.0-28.el7.10.1
CentOS-qemu-ev 516 k
replacing qemu-kvm-common.x86_64 10:1.5.3-126.el7_3.10
qemu-kvm-ev x86_64 10:2.6.0-28.el7.10.1
CentOS-qemu-ev 2.5 M
replacing qemu-kvm.x86_64 10:1.5.3-126.el7_3.10
Transaction Summary
===================================================================================================Install 3 Packages
so it seems it automatically obsoletes the “standard” packages, because they overlap in filesand you can have only one installed
And now you should have the -fw_cfg option.
BTW: the version of the hypervisor used by Virtualization SIG is the same used by the Virtualization Platform project named oVirt (
http://www.ovirt.org), upstream for commercial RHEV solution, so rock solid, I’m currently using it extensively ;-)
HIH, Gianluca
Many thanks for your quick response Gianluca. I installed the “ev”
packages and now I can pass the “fw_cfg” option to the vm.
Regards
Steve.