@item s390-squash-mcss=on|off
Enables or disables squashing subchannels into the default css.
The default is off.
+@item enforce-config-section=on|off
+If @option{enforce-config-section} is set to @var{on}, force migration
+code to send configuration section even if the machine-type sets the
+@option{migration.send-configuration} property to @var{off}.
+NOTE: this parameter is deprecated. Please use @option{-global}
+@option{migration.send-configuration}=@var{on|off} instead.
@end table
ETEXI
" [,read-only=on|off][,detect-zeroes=on|off|unmap]\n"
" [,driver specific parameters...]\n"
" configure a block backend\n", QEMU_ARCH_ALL)
+STEXI
+@item -blockdev @var{option}[,@var{option}[,@var{option}[,...]]]
+@findex -blockdev
+
+Define a new block driver node. Some of the options apply to all block drivers,
+other options are only accepted for a specific block driver. See below for a
+list of generic options and options for the most common block drivers.
+
+Options that expect a reference to another node (e.g. @code{file}) can be
+given in two ways. Either you specify the node name of an already existing node
+(file=@var{node-name}), or you define a new node inline, adding options
+for the referenced node after a dot (file.filename=@var{path},file.aio=native).
+
+A block driver node created with @option{-blockdev} can be used for a guest
+device by specifying its node name for the @code{drive} property in a
+@option{-device} argument that defines a block device.
+
+@table @option
+@item Valid options for any block driver node:
+
+@table @code
+@item driver
+Specifies the block driver to use for the given node.
+@item node-name
+This defines the name of the block driver node by which it will be referenced
+later. The name must be unique, i.e. it must not match the name of a different
+block driver node, or (if you use @option{-drive} as well) the ID of a drive.
+
+If no node name is specified, it is automatically generated. The generated node
+name is not intended to be predictable and changes between QEMU invocations.
+For the top level, an explicit node name must be specified.
+@item read-only
+Open the node read-only. Guest write attempts will fail.
+@item cache.direct
+The host page cache can be avoided with @option{cache.direct=on}. This will
+attempt to do disk IO directly to the guest's memory. QEMU may still perform an
+internal copy of the data.
+@item cache.no-flush
+In case you don't care about data integrity over host failures, you can use
+@option{cache.no-flush=on}. This option tells QEMU that it never needs to write
+any data to the disk but can instead keep things in cache. If anything goes
+wrong, like your host losing power, the disk storage getting disconnected
+accidentally, etc. your image will most probably be rendered unusable.
+@item discard=@var{discard}
+@var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls
+whether @code{discard} (also known as @code{trim} or @code{unmap}) requests are
+ignored or passed to the filesystem. Some machine types may not support
+discard requests.
+@item detect-zeroes=@var{detect-zeroes}
+@var{detect-zeroes} is "off", "on" or "unmap" and enables the automatic
+conversion of plain zero writes by the OS to driver specific optimized
+zero write commands. You may even choose "unmap" if @var{discard} is set
+to "unmap" to allow a zero write to be converted to an @code{unmap} operation.
+@end table
+
+@item Driver-specific options for @code{file}
+
+This is the protocol-level block driver for accessing regular files.
+
+@table @code
+@item filename
+The path to the image file in the local filesystem
+@item aio
+Specifies the AIO backend (threads/native, default: threads)
+@end table
+Example:
+@example
+-blockdev driver=file,node-name=disk,filename=disk.img
+@end example
+
+@item Driver-specific options for @code{raw}
+
+This is the image format block driver for raw images. It is usually
+stacked on top of a protocol level block driver such as @code{file}.
+
+@table @code
+@item file
+Reference to or definition of the data source block driver node
+(e.g. a @code{file} driver node)
+@end table
+Example 1:
+@example
+-blockdev driver=file,node-name=disk_file,filename=disk.img
+-blockdev driver=raw,node-name=disk,file=disk_file
+@end example
+Example 2:
+@example
+-blockdev driver=raw,node-name=disk,file.driver=file,file.filename=disk.img
+@end example
+
+@item Driver-specific options for @code{qcow2}
+
+This is the image format block driver for qcow2 images. It is usually
+stacked on top of a protocol level block driver such as @code{file}.
+
+@table @code
+@item file
+Reference to or definition of the data source block driver node
+(e.g. a @code{file} driver node)
+
+@item backing
+Reference to or definition of the backing file block device (default is taken
+from the image file). It is allowed to pass an empty string here in order to
+disable the default backing file.
+
+@item lazy-refcounts
+Whether to enable the lazy refcounts feature (on/off; default is taken from the
+image file)
+
+@item cache-size
+The maximum total size of the L2 table and refcount block caches in bytes
+(default: 1048576 bytes or 8 clusters, whichever is larger)
+
+@item l2-cache-size
+The maximum size of the L2 table cache in bytes
+(default: 4/5 of the total cache size)
+
+@item refcount-cache-size
+The maximum size of the refcount block cache in bytes
+(default: 1/5 of the total cache size)
+
+@item cache-clean-interval
+Clean unused entries in the L2 and refcount caches. The interval is in seconds.
+The default value is 0 and it disables this feature.
+
+@item pass-discard-request
+Whether discard requests to the qcow2 device should be forwarded to the data
+source (on/off; default: on if discard=unmap is specified, off otherwise)
+
+@item pass-discard-snapshot
+Whether discard requests for the data source should be issued when a snapshot
+operation (e.g. deleting a snapshot) frees clusters in the qcow2 file (on/off;
+default: on)
+
+@item pass-discard-other
+Whether discard requests for the data source should be issued on other
+occasions where a cluster gets freed (on/off; default: off)
+
+@item overlap-check
+Which overlap checks to perform for writes to the image
+(none/constant/cached/all; default: cached). For details or finer
+granularity control refer to the QAPI documentation of @code{blockdev-add}.
+@end table
+
+Example 1:
+@example
+-blockdev driver=file,node-name=my_file,filename=/tmp/disk.qcow2
+-blockdev driver=qcow2,node-name=hda,file=my_file,overlap-check=none,cache-size=16777216
+@end example
+Example 2:
+@example
+-blockdev driver=qcow2,node-name=disk,file.driver=http,file.filename=http://example.com/image.qcow2
+@end example
+
+@item Driver-specific options for other drivers
+Please refer to the QAPI documentation of the @code{blockdev-add} QMP command.
+
+@end table
+
+ETEXI
DEF("drive", HAS_ARG, QEMU_OPTION_drive,
"-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
@item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
@findex -drive
-Define a new drive. Valid options are:
+Define a new drive. This includes creating a block driver node (the backend) as
+well as a guest device, and is mostly a shortcut for defining the corresponding
+@option{-blockdev} and @option{-device} options.
+
+@option{-drive} accepts all options that are accepted by @option{-blockdev}. In
+addition, it knows the following options:
@table @option
@item file=@var{file}
This option defines the type of the media: disk or cdrom.
@item cyls=@var{c},heads=@var{h},secs=@var{s}[,trans=@var{t}]
These options have the same definition as they have in @option{-hdachs}.
+These parameters are deprecated, use the corresponding parameters
+of @code{-device} instead.
@item snapshot=@var{snapshot}
@var{snapshot} is "on" or "off" and controls snapshot mode for the given drive
(see @option{-snapshot}).
@item cache=@var{cache}
-@var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough" and controls how the host cache is used to access block data.
+@var{cache} is "none", "writeback", "unsafe", "directsync" or "writethrough"
+and controls how the host cache is used to access block data. This is a
+shortcut that sets the @option{cache.direct} and @option{cache.no-flush}
+options (as in @option{-blockdev}), and additionally @option{cache.writeback},
+which provides a default for the @option{write-cache} option of block guest
+devices (as in @option{-device}). The modes correspond to the following
+settings:
+
+@c Our texi2pod.pl script doesn't support @multitable, so fall back to using
+@c plain ASCII art (well, UTF-8 art really). This looks okay both in the manpage
+@c and the HTML output.
+@example
+@ │ cache.writeback cache.direct cache.no-flush
+─────────────┼─────────────────────────────────────────────────
+writeback │ on off off
+none │ on on off
+writethrough │ off off off
+directsync │ off on off
+unsafe │ on off on
+@end example
+
+The default mode is @option{cache=writeback}.
+
@item aio=@var{aio}
@var{aio} is "threads", or "native" and selects between pthread based disk I/O and native Linux AIO.
-@item discard=@var{discard}
-@var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap}) requests are ignored or passed to the filesystem. Some machine types may not support discard requests.
@item format=@var{format}
Specify which disk @var{format} will be used rather than detecting
the format. Can be used to specify format=raw to avoid interpreting
an untrusted format header.
@item serial=@var{serial}
-This option specifies the serial number to assign to the device.
+This option specifies the serial number to assign to the device. This
+parameter is deprecated, use the corresponding parameter of @code{-device}
+instead.
@item addr=@var{addr}
-Specify the controller's PCI address (if=virtio only).
+Specify the controller's PCI address (if=virtio only). This parameter is
+deprecated, use the corresponding parameter of @code{-device} instead.
@item werror=@var{action},rerror=@var{action}
Specify which @var{action} to take on write and read errors. Valid actions are:
"ignore" (ignore the error and try to continue), "stop" (pause QEMU),
"report" (report the error to the guest), "enospc" (pause QEMU only if the
host disk is full; report the error to the guest otherwise).
The default setting is @option{werror=enospc} and @option{rerror=report}.
-@item readonly
-Open drive @option{file} as read-only. Guest write attempts will fail.
@item copy-on-read=@var{copy-on-read}
@var{copy-on-read} is "on" or "off" and enables whether to copy read backing
file sectors into the image file.
-@item detect-zeroes=@var{detect-zeroes}
-@var{detect-zeroes} is "off", "on" or "unmap" and enables the automatic
-conversion of plain zero writes by the OS to driver specific optimized
-zero write commands. You may even choose "unmap" if @var{discard} is set
-to "unmap" to allow a zero write to be converted to an UNMAP operation.
@item bps=@var{b},bps_rd=@var{r},bps_wr=@var{w}
Specify bandwidth throttling limits in bytes per second, either for all request
types or for reads or writes only. Small values can lead to timeouts or hangs
instead of a single larger disk.
@end table
-By default, the @option{cache=writeback} mode is used. It will report data
+By default, the @option{cache.writeback=on} mode is used. It will report data
writes as completed as soon as the data is present in the host page cache.
This is safe as long as your guest OS makes sure to correctly flush disk caches
where needed. If your guest OS does not handle volatile disk write caches
correctly and your host crashes or loses power, then the guest may experience
data corruption.
-For such guests, you should consider using @option{cache=writethrough}. This
+For such guests, you should consider using @option{cache.writeback=off}. This
means that the host page cache will be used to read and write data, but write
notification will be sent to the guest only after QEMU has made sure to flush
each write to the disk. Be aware that this has a major impact on performance.
-The host page cache can be avoided entirely with @option{cache=none}. This will
-attempt to do disk IO directly to the guest's memory. QEMU may still perform
-an internal copy of the data. Note that this is considered a writeback mode and
-the guest OS must handle the disk write cache correctly in order to avoid data
-corruption on host crashes.
-
-The host page cache can be avoided while only sending write notifications to
-the guest when the data has been flushed to the disk using
-@option{cache=directsync}.
-
-In case you don't care about data integrity over host failures, use
-@option{cache=unsafe}. This option tells QEMU that it never needs to write any
-data to the disk but can instead keep things in cache. If anything goes wrong,
-like your host losing power, the disk storage getting disconnected accidentally,
-etc. your image will most probably be rendered unusable. When using
-the @option{-snapshot} option, unsafe caching is always used.
+When using the @option{-snapshot} option, unsafe caching is always used.
Copy-on-read avoids accessing the same backing file sectors repeatedly and is
useful when the backing file is over a slow network. By default copy-on-read
DEF("fsdev", HAS_ARG, QEMU_OPTION_fsdev,
"-fsdev fsdriver,id=id[,path=path,][security_model={mapped-xattr|mapped-file|passthrough|none}]\n"
- " [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n"
+ " [,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]\n"
" [[,throttling.bps-total=b]|[[,throttling.bps-read=r][,throttling.bps-write=w]]]\n"
" [[,throttling.iops-total=i]|[[,throttling.iops-read=r][,throttling.iops-write=w]]]\n"
" [[,throttling.bps-total-max=bm]|[[,throttling.bps-read-max=rm][,throttling.bps-write-max=wm]]]\n"
STEXI
-@item -fsdev @var{fsdriver},id=@var{id},path=@var{path},[security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}]
+@item -fsdev @var{fsdriver},id=@var{id},path=@var{path},[security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}][,fmode=@var{fmode}][,dmode=@var{dmode}]
@findex -fsdev
Define a new file system device. Valid options are:
@table @option
Enables proxy filesystem driver to use passed socket descriptor for
communicating with virtfs-proxy-helper. Usually a helper like libvirt
will create socketpair and pass one of the fds as sock_fd
+@item fmode=@var{fmode}
+Specifies the default mode for newly created files on the host. Works only
+with security models "mapped-xattr" and "mapped-file".
+@item dmode=@var{dmode}
+Specifies the default mode for newly created directories on the host. Works
+only with security models "mapped-xattr" and "mapped-file".
@end table
-fsdev option is used along with -device driver "virtio-9p-pci".
DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs,
"-virtfs local,path=path,mount_tag=tag,security_model=[mapped-xattr|mapped-file|passthrough|none]\n"
- " [,id=id][,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd]\n",
+ " [,id=id][,writeout=immediate][,readonly][,socket=socket|sock_fd=sock_fd][,fmode=fmode][,dmode=dmode]\n",
QEMU_ARCH_ALL)
STEXI
-@item -virtfs @var{fsdriver}[,path=@var{path}],mount_tag=@var{mount_tag}[,security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}]
+@item -virtfs @var{fsdriver}[,path=@var{path}],mount_tag=@var{mount_tag}[,security_model=@var{security_model}][,writeout=@var{writeout}][,readonly][,socket=@var{socket}|sock_fd=@var{sock_fd}][,fmode=@var{fmode}][,dmode=@var{dmode}]
@findex -virtfs
The general form of a Virtual File system pass-through options are:
@item sock_fd
Enables proxy filesystem driver to use passed 'sock_fd' as the socket
descriptor for interfacing with virtfs-proxy-helper
+@item fmode=@var{fmode}
+Specifies the default mode for newly created files on the host. Works only
+with security models "mapped-xattr" and "mapped-file".
+@item dmode=@var{dmode}
+Specifies the default mode for newly created directories on the host. Works
+only with security models "mapped-xattr" and "mapped-file".
@end table
ETEXI
@item key-delay-ms
Set keyboard delay, for key down and key up events, in milliseconds.
-Default is 1. Keyboards are low-bandwidth devices, so this slowdown
+Default is 10. Keyboards are low-bandwidth devices, so this slowdown
can help the device and guest to keep up and not lose events in case
events are arriving in bulk. Possible causes for the latter are flaky
network connections, or scripts for automated testing.
The simplest secure usage is to provide the secret via a file
- # echo -n "letmein" > mypasswd.txt
+ # printf "letmein" > mypasswd.txt
# $QEMU -object secret,id=sec0,file=mypasswd.txt,format=raw
For greater security, AES-256-CBC should be used. To illustrate usage,
as raw bytes if desired.
@example
- # SECRET=$(echo -n "letmein" |
+ # SECRET=$(printf "letmein" |
openssl enc -aes-256-cbc -a -K $KEY -iv $IV)
@end example
projects / qemu.git / blobdiff