scripts

https://github.com/fzinfz/scripts/blob/master/lib/qemu.sh

qemu-img

tar -xvf x.ova
qemu-img resize foo.qcow2 +2G # thin
qemu-img convert -p -f raw -O vhdx -o subformat=dynamic x.img x.vhdx

qemu-img-windows

https://cloudbase.it/qemu-img-windows/

virtiofs

https://virtio-fs.gitlab.io/
Virtio-fs is used in production and has been available since Linux 5.4, QEMU 5.0, and libvirt 6.2.

https://libvirt.org/kbase/virtiofs.html

qemu-nbd

https://manpages.debian.org/testing/qemu-utils/qemu-nbd.8.en.html

Export a QEMU disk image using the NBD protocol.
Bind a /dev/nbdX block device to a QEMU server (on Linux).
As a client to query exports of a remote NBD server.

virtio-mem

https://virtio-mem.gitlab.io/

Releases

https://wiki.qemu.org/ChangeLog

5.2
    A new KVM feature which improves the handling of asynchronous page faults is available with -cpu ...,kvm-async-pf-int. This requires Linux 5.8.
5.1
    Support for live migration of AMD systems with nested virtualization
    A first version of virtio-mem, including virtio-mem-pci, for x86-64 has been included in QEMU. 
5.0
    Support for passing host filesystem directory to guest via virtiofsd
4.2
    VMX features can be enabled/disabled via the "-cpu" flag.
    Audio devices support an "audiodev" property that can be used to choose a specific backend to connect to the device.    
4.1
    virtio-gpu 2d/3d rendering may now be offloaded to an external vhost-user process, such as QEMU vhost-user-gpu. Use vhost-user-vga & vhost-user-gpu-pci for associated devices. 
4.0
    EDID interface for supported mdevs (Intel vGPU, host kernel v5.0+). Use options xres= and yres= to specify display resolution.
    qcow2: Support for external data files
3.1
    Support for AMD IOMMU interrupt remapping and guest virtual APIC mode.
3.0
    Formatting of CPU models and flags reported with '-cpu help' has improved readability
2.12
    The default NIC for the q35 machine type is now e1000e (Intel 82574)
    Support for the "dedicated physical CPU" performance hint ("-cpu kvm-hint-dedicated=on")
2.11
    KVM can advertise Hyper-V frequency MSRs when the TSC frequency is stable and known
    QXL adds support for chunked cursors.
    Support for generic PCIe to PCI bridge device pcie-pci-bridge, which supports SHPC and can replace the i82801b11 DMI to PCI bridge.
    PCI bridges can pass information to the firmware regarding reservation of bus numbers, IO space and memory.
    Support for TPM emulator
    Experimental support for NVIDIA GPUDirect Cliques
2.10.0 - Debian 10 & Ubuntu 17.10 artful 18.04 bionic
    QEMU is broken since 2.10 with Linux kernels < v3.15
    Support for Solaris 9 and earlier has been removed.
    qxl and virtio-gpu support two new properties for the default display resolution, xres and yres
    Support for the vxhs(Veritas HyperScale) network protocol
    "qemu-img resize" supports preallocation of the new parts of the image.
    additional docker targets have been added which allow cross compilation build tests for arm, powerpc and mips. Run "make docker" for help.
2.8 - Debian 9 stretch / 8 jessie-backports & Ubuntu 17.04 zesty/zesty-updates
2.5 - Ubuntu 16.04 xenial/xenial-updates
2.1 - Debian 8 jessie
2.0 - Ubuntu 14.04 trusty/trusty-updates

qemu-system

qemu-system-aarch64       qemu-system-m68k          qemu-system-mipsel        qemu-system-s390x         qemu-system-unicore32
qemu-system-alpha         qemu-system-microblaze    qemu-system-moxie         qemu-system-sh4           qemu-system-x86_64
qemu-system-arm           qemu-system-microblazeel  qemu-system-or32          qemu-system-sh4eb         qemu-system-x86_64-spice
qemu-system-cris          qemu-system-mips          qemu-system-ppc           qemu-system-sparc         qemu-system-xtensa
qemu-system-i386          qemu-system-mips64        qemu-system-ppc64         qemu-system-sparc64       qemu-system-xtensaeb
qemu-system-lm32          qemu-system-mips64el      qemu-system-ppcemb        qemu-system-tricore

# qemu-system-x86_64 -M ?
Supported machines are:
pc                   Standard PC (i440FX + PIIX, 1996) (alias of pc-i440fx-2.9)
pc-i440fx-2.9        Standard PC (i440FX + PIIX, 1996) (default)
q35                  Standard PC (Q35 + ICH9, 2009) (alias of pc-q35-2.9)
isapc                ISA-only PC
none                 empty machine