ChangeLog/2.2

System emulation

Future incompatible changes

• Three options are using different names on the command line and in configuration file. In particular:
  • The "acpi" configuration file section matches command-line option "acpitable";
  • The "boot-opts" configuration file section matches command-line option "boot";
  • The "smp-opts" configuration file section matches command-line option "smp".

Starting with QEMU xyz.jkl, -readconfig will standardize on the name for the command line option.

ARM

• Initial support for emulation of hypervisor (EL2) and secure (EL3) privilege levels
• Support for loading a device tree even with no -kenel option or when booting ELF images
• Support for input interrupts in the PL061 GPIO controller
• TCG can emulate breakpoints and watchpoints.

PowerPC

• Mac OS X 10.2, 10.3 and 10.4 guests run with the mac99 machine type.
• Bugfixes and optimization for TCG emulation of PowerPC targets.

IBM (pSeries)

• Support for the "nmi" monitor command, to enter the kernel debugger.

Freescale (BookE)

• Breakpoint support on KVM.

s390

• Enhance support for boot from DASD to handle more formats.
• Support for memory hotplug.

SPARC

• Emulation of TCX hardware acceleration.

TriCore

• New target.

x86

• Support for IOMMU (VT-d) emulation on the Q35 machine type, enabled with "-machine iommu=on"

KVM

• More robust live migration of the kvm pv clock

Xen

• QEMU can now boot a bzImage or multiboot kernel under Xen, using the command line option -kernel.

Device emulation and assignment

SCSI

• Passthrough of vendor-specific commands now works (only with the virtio-scsi HBA).

PCI/PCIe

• MSIs are now (correctly) disabled until bus master DMA is enabled for the device.
• Support for ARI forwarding on PCIe root ports.

USB

• Support for hot-plugging XHCI/EHCI/UHCI controllers (in the case of EHCI/UHCI, only if there are no companion controllers)

Block devices in system emulation

• Many fixes to AHCI emulation.
• The list of functionality now supported in threaded virtio-blk backend is growing: new in 2.2 are resizing of disks, device hot-unplug, and the embedded NBD server.

Block devices and tools

• Support for Archipelago as a QEMU block backend
• QEMU is more resistent against failure of large allocations in the block layer
• Support for Parallels images larger than 2TB.
• Network-based drivers (NBD, libiscsi, etc.) now work on Win32 hosts too.
• qemu-img source cache option?
• qemu-nbd has a new --detect-zeroes option.

TCG

• In icount mode, it is possible to slow down emulation to match the requested CPU frequency (thus ensuring that the host and guest clocks remain aligned). This is enabled with "-icount N,align=on".
• A new "victim TLB" provides a 5-10% performance improvement.

Tracing

• QEMU provides a SystemTap script that outputs binary trace data, for use in flight-recorder mode. The resulting traces can be parsed with QEMU's simpletrace.py script (using the --no-header command-line option).