According to the QEMU website:
QEMU is a generic and open source machine emulator and virtualizer.
When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performance.
When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. QEMU supports virtualization when executing under the Xen hypervisor or using the KVM kernel module in Linux. When using KVM, QEMU can virtualize x86, server and embedded PowerPC, and S390 guests.
Fast-forward to QEMU's latest 1.7.0 release, which adds a number of new features to the project. These new features may not seem as sexy as some it has made in the past, such as live migration for guests, support for SSD and thin provisioning, adding support for Large Physical Address Extensions (LPAE) ARM technology on platforms with Cortex CPUs, or GPU pass-through from host to guest. But these updates are no less important -- even if they only appeal to the geekier virtualization users like me.
Some of the new highlights worth mentioning in this latest stable release include:
- Several enhancements for audio support within guest virtual machines
- Additional device assignment control using Virtual Function I/O (VFIO), a user space driver framework designed to pass through PCI and PCIe devices to guests, allowing them to access these devices at low latency and high data throughput levels without any risk to the host
- Performance and functionality improvements for USB 3.0
- Virtual disk image updates, including driver support for VMware's VMDK files produced by ESX; the qcow2 driver can now detect some cases of corruption and prevent writing to a corrupted image; and support has been added for creating and writing VHDX images from Microsoft Hyper-V
- The "filesystem freeze/thaw" commands are now supported on Windows where they will invoke the native Volume Shadow Copy Service (VSS)
In addition, you'll find important x86 updates:
- Guests can access the ACPI tables of the host servers directly, which in the future will enable new features without modifications of all firmware components (SeaBIOS, OVMF, CoreBoot).
- Initial support for more than 1TB of RAM.
- Xen HVM domains can now resume from suspend-to-RAM (S3) state.
Again, I'm thankful for virtualization. It has completely changed my work life for the better in so many different ways.
Thankfully, QEMU has been innovating for the past 10 years, helping to improve virtualization as well as cloud computing.