ChangeLog/0.14

QEMU 0.14.0 IS NOT YET RELEASED

0.14.0

Devices

virtio

• virtio-pci can use ioeventfd for virtqueue notify. On systems that support KVM, the ioeventfd mechanism can be used to make virtqueue notify a lightweight exit by deferring hardware emulation to the iothread and allowing the VM to continue execution. This model is similar to how vhost receives virtqueue notifies. The result of this change is improved performance for userspace virtio devices. Virtio-blk throughput increases especially for multithreaded scenarios and virtio-net transmit throughput increases substantially. Read the commit message for more details. (commit) (commit) For more information about ioeventd: http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d34e6b175e61821026893ec5298cc8e7558df43a

Sound

• New Intel HD Audio support (commit), adding three new devices:
  • intel-hda: Intel HD Audio Controller, the PCI device.
  • hda-duplex: HDA Codec. Attaches to the HDA bus. Supports 16bit stereo, rates 16k -> 96k, playback, recording and volume control (with CONFIG_MIXEMU=y).
  • hda-output: HDA Codec without recording support. Subset of the hda-duplex codec. Use this if you don't want your guests access your mic.
• Usage: add '-device intel-hda -device hda-duplex' to your command line.
• Tested guests:
  • Linux works.
  • Win7 works.
  • DOS (mpxplay) works.
  • WinXP doesn't work.

Block Drivers

qcow2

• Add QcowCache. Improves performance of scenarios with lots of cluster allocations noticably (e.g. installation or after taking a snapshot).(commit) (commit) (commit)
• Copy snapshots out of QCOW2 disk, eg: qemu-img convert -f qcow2 -O qcow2 -s snapshot_name src_img bck_img (commit)

• Other fixes:
  • qcow2: fix unaligned access (commit)
  • Add proper -errno error return values to qcow2_open() (commit)
  • block/qcow2.c: rename qcow_ functions to qcow2_ (commit)
  • block: Remove unused s->hd in various drivers (commit)
  • qcow2: Invalidate cache after failed read (commit)
  • block: Allow bdrv_flush to return errors (commit)
  • qcow2: Remove old image creation function (commit)

qed

• Introduction of the QEMU Enhanced Disk (qed) image format. It is a disk image format that forgoes features found in qcow2 in favor of better levels of performance and data integrity. Due to its simpler on-disk layout, it is possible to safely perform metadata updates more efficiently. (commit)

(commit) (commit)

• More information about qed: http://wiki.qemu.org/Features/QED
• Initial thread discussion: http://lists.nongnu.org/archive/html/qemu-devel/2010-09/msg00310.html

ceph/rbd

• Introduction of the new ceph/rbd block driver. RBD is an block driver for the distributed file system Ceph.(commit)
• More information about ceph: http://ceph.newdream.net/

nbd

• Improve qemu-nbd performance by 4400 %. This patch combines the reply header and payload send operation. (commit)
• Introduce NBD named exports. (commit)

Spice

• New support for the SPICE protocol. The project main focus is to provide high-quality remote access to QEMU virtual machines. More information about SPICE can be found at the project's web site: http://spice-space.org/
• New qxl device. qxl is a paravirtual graphics card. The qxl device is the bridge between the guest and the spice server (aka libspice-server). The spice server will send the rendering commands to the spice client, which will actually render them. The spice server is also able to render locally, which is done in case the guest wants read something from video memory. Local rendering is also used to support display over vnc and sdl. qxl is activated using -vga qxl. qxl supports multihead, additional cards can be added via '-device qxl.
• Relevant commits:
  • spice: core bits (commit)
  • spice: add keyboard (commit)
  • spice: add mouse (commit)
  • spice: simple display (commit)
  • spice: add tablet support (commit)
  • spice: tls support (commit)
  • spice: make compression configurable. (commit)
  • spice: add config options for channel security. (commit)
  • spice: add config options for the listening address (commit)
  • spice: add misc config options (commit)
  • spice: add audio (commit)
  • Merge remote branch 'spice/bugfix.2' into staging (commit)
  • spice: add qxl device (commit)
  • spice: connection events. (commit)

QMP / monitor

• The work to facilitate the management of QEMU instances has been improved. QMP has received various fixes. Now it is possible to call a traditional monitor command through QMP, in case your application depends on the output or the command is not yet ported to QMP.
• New commands:
  • query-spice / info spice (commit)
  • human-monitor-command (commit) (commit)
  • set_password (commit)