Category Archives: libvirt

Use the Qemu guest agent with Memory Overcommitment Manager

Qemu now has an official guest agent. Programs on a KVM host can now talk to guests using a virtual hardware channel (either virtio-serial or an emulated ISA serial port). Using this mechanism, it is now possible to reliably power … Continue reading

Posted in KVM, libvirt, MOM, qemu | 37 Comments

What is the IP address of my guest?

When using libvirt to create virtual machines, I find that networking works pretty well right out of the box. My VMs are connected to one another via a virtual subnet and have outbound access to the internet. But there is … Continue reading

Posted in libvirt | 2 Comments

HOWTO: Add libvirt support for a qemu command

If you are a qemu developer, one task you’ll inevitably do is add a new command to qemu. If you want your command to be usable by tools such as virt-manager, you will also need to add support for your … Continue reading

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A crazy idea to improve QEMU/Libvirt interoperability

On two separate occasions I have had the opportunity to enable a new QEMU API in libvirt. The first API is a memory statistics reporting interface that can be useful for managing guest memory ballooning. (For the curious, this is … Continue reading

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Automatic Memory Ballooning with MOM

In this post, I will describe how to use Memory Overcommitment Manager (MOM) to automatically manage memory ballooning on a KVM host. Memory ballooning is a virtualization feature that allows youto apply a “soft” memory limit to your virtual machines. … Continue reading

Posted in libvirt, MOM | 24 Comments

How to hack on a local copy of libvirt

So you want to run a version of libvirt other than packaged version on your system. ¬†You might want to do this to see if a bug you found has been fixed in a later release, or to develop your … Continue reading

Posted in libvirt | 5 Comments