space. Use @code{qemu-img info} to know the real size used by the
image or @code{ls -ls} on Unix/Linux.
+Supported options:
+@table @code
+@item preallocation
+Preallocation mode (allowed values: @code{off}, @code{falloc}, @code{full}).
+@code{falloc} mode preallocates space for image by calling posix_fallocate().
+@code{full} mode preallocates space for image by writing zeros to underlying
+storage.
+@end table
+
@item qcow2
QEMU image format, the most versatile format. Use it to have smaller
images (useful if your filesystem does not supports holes, for example
-on Windows), optional AES encryption, zlib based compression and
-support of multiple VM snapshots.
+on Windows), zlib based compression and support of multiple VM
+snapshots.
Supported options:
@table @code
though even this is ineffective with many modern storage technologies.
@end itemize
-Use of qcow / qcow2 encryption is thus strongly discouraged. Users are
-recommended to use an alternative encryption technology such as the
-Linux dm-crypt / LUKS system.
+Use of qcow / qcow2 encryption with QEMU is deprecated, and support for
+it will go away in a future release. Users are recommended to use an
+alternative encryption technology such as the Linux dm-crypt / LUKS
+system.
@item cluster_size
Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
provide better performance.
@item preallocation
-Preallocation mode (allowed values: off, metadata). An image with preallocated
-metadata is initially larger but can improve performance when the image needs
-to grow.
+Preallocation mode (allowed values: @code{off}, @code{metadata}, @code{falloc},
+@code{full}). An image with preallocated metadata is initially larger but can
+improve performance when the image needs to grow. @code{falloc} and @code{full}
+preallocations are like the same options of @code{raw} format, but sets up
+metadata also.
@item lazy_refcounts
If this option is set to @code{on}, reference count updates are postponed with
If this option is set to @code{on}, the image is encrypted.
@end table
-@item cow
-User Mode Linux Copy On Write image format. It is supported only for
-compatibility with previous versions.
-Supported options:
-@table @code
-@item backing_file
-File name of a base image (see @option{create} subcommand)
-@end table
-
@item vdi
VirtualBox 1.1 compatible image format.
Supported options:
Specifies which VHDX subformat to use. Valid options are
@code{dynamic} (default) and @code{fixed}.
@item block_state_zero
-Force use of payload blocks of type 'ZERO'.
+Force use of payload blocks of type 'ZERO'. Can be set to @code{on} (default)
+or @code{off}. When set to @code{off}, new blocks will be created as
+@code{PAYLOAD_BLOCK_NOT_PRESENT}, which means parsers are free to return
+arbitrary data for those blocks. Do not set to @code{off} when using
+@code{qemu-img convert} with @code{subformat=dynamic}.
@item block_size
Block size; min 1 MB, max 256 MB. 0 means auto-calculate based on image size.
@item log_size
On Linux, you can directly use the host device filename instead of a
disk image filename provided you have enough privileges to access
-it. For example, use @file{/dev/cdrom} to access to the CDROM or
-@file{/dev/fd0} for the floppy.
+it. For example, use @file{/dev/cdrom} to access to the CDROM.
@table @code
@item CD
removal is currently not detected accurately (if you change floppy
without doing floppy access while the floppy is not loaded, the guest
OS will think that the same floppy is loaded).
+Use of the host's floppy device is deprecated, and support for it will
+be removed in a future release.
@item Hard disks
Hard disks can be used. Normally you must specify the whole disk
(@file{/dev/hdb} instead of @file{/dev/hdb1}) so that the guest OS can
the address 10.0.2.2 and verify that you got an address in the range
10.0.2.x from the QEMU virtual DHCP server.
-Note that @code{ping} is not supported reliably to the internet as it
-would require root privileges. It means you can only ping the local
-router (10.0.2.2).
+Note that ICMP traffic in general does not work with user mode networking.
+@code{ping}, aka. ICMP echo, to the local router (10.0.2.2) shall work,
+however. If you're using QEMU on Linux >= 3.0, it can use unprivileged ICMP
+ping sockets to allow @code{ping} to the Internet. The host admin has to set
+the ping_group_range in order to grant access to those sockets. To allow ping
+for GID 100 (usually users group):
+
+@example
+echo 100 100 > /proc/sys/net/ipv4/ping_group_range
+@end example
When using the built-in TFTP server, the router is also the TFTP
server.
# certtool --generate-certificate \
--load-ca-certificate ca-cert.pem \
--load-ca-privkey ca-key.pem \
- --load-privkey server server-key.pem \
+ --load-privkey server-key.pem \
--template server.info \
--outfile server-cert.pem
@end example
country = GB
state = London
locality = London
-organiazation = Name of your organization
+organization = Name of your organization
cn = client.foo.example.com
tls_www_client
encryption_key
A sample Linux 2.6 series kernel and ram disk image are available on
the QEMU web site. There are still issues with NetBSD and OpenBSD, but
-some kernel versions work. Please note that currently older Solaris kernels
+most kernel versions work. Please note that currently older Solaris kernels
don't work probably due to interface issues between OpenBIOS and
Solaris.
Use the executable @file{qemu-system-sparc64} to simulate a Sun4u
(UltraSPARC PC-like machine), Sun4v (T1 PC-like machine), or generic
-Niagara (T1) machine. The emulator is not usable for anything yet, but
-it can launch some kernels.
+Niagara (T1) machine. The Sun4u emulator is mostly complete, being
+able to run Linux, NetBSD and OpenBSD in headless (-nographic) mode. The
+Sun4v and Niagara emulators are still a work in progress.
QEMU emulates the following peripherals:
projects / mirror_qemu.git / blobdiff