ChangeLog/2.0

System emulation

Support for "-M virt", a board type that only uses virtio devices
Support for "-cpu host" when running under KVM
Support for new ARMv8 instructions in TCG
Support for AArch64 disassembling (requires a C++ compiler to be installed on the host)
Support for AArch64 user-mode emulation
Support for AArch64 system-mode emulation using KVM
Support for the Canon PowerShot A1100 DIGIC board using "-M canon-a1100"
Support for the allwinner-a10-based board "-M cubieboard"
Support for flow control in the Cadence UART

Support for Altivec 2.07 and VSX instructions when running under TCG
Support for ISA 2.06 "load/store quadword instructions", "divide extended instructions" and "floating-point test instructions" when running under TCG
Prep is not anymore (incorrectly) included in qemu-system-ppcemb

Support for Sun CG3 framebuffer with the Sun4m machine. The CG3 framebuffer can be requested with "-vga cg3".

On the Q35 machine, the HPET interrupt can now be attached to GSIs 16-23, like on real hardware.
The Q35 machine now supports CPU hotplug.
Two flash chips can be specified using the "-drive if=pflash" or "-pflash" options twice.
Memory layout has changed slightly; to improve performance, the PIIX4 machine ("-M pc") now has 3GB of low memory instead of 3.5GB if the guest has more than 3.5GB of memory. Similarly, the Q35 machine ("-M q35") now has 2GB instead of 2.75GB of low memory if the guest has more than 2.75GB of overall memory.
Support for migration of Intel MPX registers.
The Apple SMC device is now exposed in the ACPI tables.
PCI hotplug now supports devices behind a bridge (only for bridges not added by hotplug; hot-plugged bridges can still use the PCI Standard Hot-Plug Controller).
Support for the Hyper-V reference time counter via the "hv-time" suboption of "-cpu". This can improve performance of Windows guests substantially for applications that do many floating-point or SIMD operations. (Requires KVM and Linux 3.14).

the SCSI layer can offload the WRITE SAME command to the host storage. This is supported on XFS file systems, raw devices, and iSCSI targets.
SCSI disks can report a port WWN and port index, to make them look more like "real" SAS disks

support for suspend-to-RAM in the XHCI controller
support for Microsoft descriptors, to make Windows use remote suspend by default.

setting the password via monitor command will not enable password auth as side effect any more. Use "qemu -vnc ${display},password" on the command line to enable password authentication.

New HMP command cpu-add for CPU hotplug
New QMP commands object-add and object-del for generic object hotplug (enables virtio-rng hotplug)
New HMP commands object_add and object_del for generic object hotplug
Improved command-line completion for device_add and device_del (as well as the new commands object_add and object_del)
dump-guest-memory can produce kdump compressed format.

Reduction (or elimination) of guest stalls during migration
RDMA migration is now activated with the "rdma:HOST:PORT" syntax (used to be "x-rdma:HOST:PORT")

Live snapshot merge (...-commit) can be used to merge the active layer of an image into one of the snapshots
Live and offline snapshot merge ("commit") will resize the destination image if necessary.
The iSCSI and Gluster backends support snapshot merge.
"query-block-stats" provides statistics for all images in the chain of backing files
node-name, query-named-block-nodes: external snapshot, resize, change password (???)

Network block drivers (curl, iscsi, rbd, ssh, glusterfs) can be built as shared library modules with "--enable-modules" configure option.
When the destination of "qemu-img convert" is a raw device, qemu-img can ask the host storage to "discard" it instead of writing zeroes
"qemu-img convert" can be passed a "-S 0" option to create a fully allocated image
"qemu-img convert" can use hints from the host storage to speed up the transfer
"qemu-img convert", "qemu-img create", "qemu-img amend" support multiple occurrences of the "-o" command line option.
The libcurl interface had bitrotted and has been fixed.
A new "quorum" driver for redundant storage is supported.
QEMU is able to operate even if the underlying storage requires the buffer size to be a 4K multiple. This is the case for 4K-native disks (with cache=none or when accessed through iscsi:// URLs) and some raw devices. When this happens, QEMU emulates unaligned accesses using read-modify-write cycles if necessary. On properly configured guests newer than ~2009 there should be no performance penalty.
qemu-io supports command editing via readline
Pseudo-protocols like blkdebug and blkverify can be nested arbitrarily
Improved error messages for many operations
QEMU can access NFSv3 shares directly from userspace using libnfs. The share must be configured to allow access from high-numbered ports

Improvements to the TCG optimizer make it produce faster code
QEMU can use getauxval to detect the host instruction set for PPC64, ARM, s390
QEMU supports generating MOVBE, ANDN, instructions in the x86 backend
Support for AArch64 disassembling (requires a C++ compiler to be installed on the host)