-M machine_type

Specifies the type of the emulated machine. Run qemu-kvm -M ? to view a list of supported machine types.

tux@venus:~> qemu-kvm -M ?
Supported machines are:
pc         Standard PC (alias of pc-0.12)
pc-0.12    Standard PC (default)
pc-0.11    Standard PC, qemu 0.11
pc-0.10    Standard PC, qemu 0.10
isapc      ISA-only PC

Currently, SUSE supports only pc-0.12 and pc-0.14machine types.

-m megabytes

Specifies how many megabytes are used for the virtual RAM size. Default is 512 MB.

-balloon virtio

Specifies a paravirtualized device to dynamically change the amount of virtual RAM memory assigned to VM Guest. The top limit is the amount of memory specified with -m.

-cpu cpu_model

Specifies the type of the processor (CPU) model. Run qemu-kvm -cpu ? to view a list of supported CPU models.

tux@venus:~> qemu-kvm -cpu ?
x86           qemu64
x86           phenom
x86         core2duo
x86            kvm64
x86           qemu32
x86          coreduo
x86              486
x86          pentium
x86         pentium2
x86         pentium3
x86           athlon
x86             n270

-smp number_of_cpus

Specifies how many CPUs will be emulated. QEMU supports up to 255 CPUs on the PC platform (up to 64 with KVM acceleration used). This option also takes other CPU-related parameters, such as number of sockets, number of cores per socket, or number of threads per core.

-no-acpi

Disables ACPI support. Try to use it if VM Guest reports problems with ACPI interface.

-S

QEMU starts with CPU stopped. To start CPU, enter c in QEMU monitor. For more information, see Chapitre 13, Administrating Virtual Machines with QEMU Monitor.

-readconfig cfg_file

Instead of entering the devices configuration options on the command line each time you want to run VM Guest, qemu-kvm can read it from a file which was either previously saved with -writeconfig or edited manually.

-writeconfig cfg_file

Dumps the current virtual machine devices configuration to a text file. It can be consequently re-used with the -readconfig option.

tux@venus:~> qemu-kvm -name "SLES 11 SP1" -M pc-0.12 -m 512 -cpu kvm64 \
-smp 2 /images/sles11sp1.raw -writeconfig /images/sles11sp1.cfg
(exited)
tux@venus:~> more /images/sles11sp1.cfg
# qemu config file

[drive]
  index = "0"
  media = "disk"
  file = "/images/sles11sp1_base.raw"

This way you can effectively manage the configuration of your virtual machines' devices in a well-arranged way.

-rtc options

Specifies the way the RTC is handled inside a VM Guest. By default, the clock of the guest is derived from that of the host system. Therefore, it is recommended that the host system clock is synchronized with an accurate external clock (for example, via NTP service).

If you need to isolate the VM Guest clock from the host one, specify clock=vm instead of the default clock=host.

You can also specify a 'starting point' for VM Guest clock with the base option:

qemu-kvm [...] -rtc clock=vm,base=2010-12-03T01:02:00

Instead of a timestamp, you can specify utc or localtime. The former instructs VM Guest to start at the current UTC value (Coordinated Universal Time, see http://en.wikipedia.org/wiki/UTC), while the latter applies the local time setting.

Sub-options for the -drive Option

file=image_fname

Specifies the path to the disk image which will be used with this drive. If not specified, an empty (removable) drive is assumed.

if=drive_interface

Specifies the type of interface to which the drive is connected. Currently only floppy, ide, or virtio are supported by SUSE. virtio defines a paravirtualized disk driver. Default is ide.

index=index_of_connector

Specifies the index number of a connector on the disk interface (see the if option) where the drive is connected. If not specified, the index is automatically incremented.

media=type

Specifies the type of the media. Can be disk for hard disks, or cdrom for removable CD-ROM drives.

format=img_fmt

Specifies the format of the connected disk image. If not specified, the format is autodetected. Currently, SUSE supports qcow2, qed and raw formats.

cache=method

Specifies the caching method for the drive. Possible values are unsafe, writethrough, writeback, or none. For the qcow2 image format, choose writeback if you care about performance. none disables the host page cache and, therefore, is the safest option. Default is writethrough.

null

Creates an empty device which outputs no data and drops any data it receives.

stdio

Connects to QEMU's process standard input and standard output.

socket

Creates a two-way stream socket. If path is specified, a Unix socket is created:

qemu-kvm [...] -chardev \
socket,id=unix_socket1,path=/tmp/unix_socket1,server

The server suboption specifies that the socket is a listening socket.

If port is specified, a TCP socket is created:

qemu-kvm [...] -chardev \
socket,id=tcp_socket1,host=localhost,port=7777,server,nowait

The command creates a local listening (server) TCP socket on port 7777. QEMU will not block waiting for a client to connect to the listening port (nowait).

udp

Sends all network traffic from VM Guest to a remote host over the UDP protocol.

qemu-kvm [...] -chardev udp,id=udp_fwd,host=mercury.example.com,port=7777

The command binds port 7777 on the remote host mercury.example.com and sends VM Guest network traffic there.

vc

Creates a new QEMU text console. You can optionally specify the dimensions of the virtual console:

qemu-kvm [...] -chardev vc,id=vc1,width=640,height=480 -mon chardev=vc1

The command creates a new virtual console called vc1 of the specified size, and connects the QEMU monitor to it.

file

Logs all traffic from VM Guest to a file on VM Host Server. The path is required and will be created if it does not exist.

qemu-kvm [...] -chardev file,id=qemu_log1,path=/var/log/qemu/guest1.log

-serial char_dev

Redirects the VM Guest's virtual serial port to a character device char_dev on VM Host Server. By default, it is a virtual console (vc) in graphical mode, and stdio in non-graphical mode. The -serial understands many suboptions. See the manual page man 1 qemu-kvm for their complete list.

You can emulate up to 4 serial ports. Use -serial none to disable all serial ports.

-parallel device

Redirects the VM Guest's parallel port to a device. This option supports the same devices as -serial.

With openSUSE or SUSE Linux Enterprise Server as a VM Host Server, you can directly use the hardware parallel port devices /dev/parportN where N is the number of the port.

You can emulate up to 3 parallel ports. Use -parallel none to disable all parallel ports.

-monitor char_dev

Redirects the QEMU monitor to a character device char_dev on VM Host Server. This option supports the same devices as -serial. By default, it is a virtual console (vc) in a graphical mode, and stdio in non-graphical mode.