ERST
DEF("smp", HAS_ARG, QEMU_OPTION_smp,
- "-smp [[cpus=]n][,maxcpus=maxcpus][,sockets=sockets][,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n"
+ "-smp [[cpus=]n][,maxcpus=maxcpus][,drawers=drawers][,books=books][,sockets=sockets]\n"
+ " [,dies=dies][,clusters=clusters][,cores=cores][,threads=threads]\n"
" set the number of initial CPUs to 'n' [default=1]\n"
" maxcpus= maximum number of total CPUs, including\n"
" offline CPUs for hotplug, etc\n"
- " sockets= number of sockets on the machine board\n"
+ " drawers= number of drawers on the machine board\n"
+ " books= number of books in one drawer\n"
+ " sockets= number of sockets in one book\n"
" dies= number of dies in one socket\n"
" clusters= number of clusters in one die\n"
" cores= number of cores in one cluster\n"
ERST
-HXCOMM Deprecated by -audiodev
-DEF("audio-help", 0, QEMU_OPTION_audio_help,
- "-audio-help show -audiodev equivalent of the currently specified audio settings\n",
- QEMU_ARCH_ALL)
-SRST
-``-audio-help``
- Will show the -audiodev equivalent of the currently specified
- (deprecated) environment variables.
-ERST
-
DEF("audio", HAS_ARG, QEMU_OPTION_audio,
+ "-audio [driver=]driver[,prop[=value][,...]]\n"
+ " specifies default audio backend when `audiodev` is not\n"
+ " used to create a machine or sound device;"
+ " options are the same as for -audiodev\n"
"-audio [driver=]driver,model=value[,prop[=value][,...]]\n"
" specifies the audio backend and device to use;\n"
" apart from 'model', options are the same as for -audiodev.\n"
" use '-audio model=help' to show possible devices.\n",
QEMU_ARCH_ALL)
SRST
-``-audio [driver=]driver,model=value[,prop[=value][,...]]``
- This option is a shortcut for configuring both the guest audio
- hardware and the host audio backend in one go.
- The driver option is the same as with the corresponding ``-audiodev`` option below.
- The guest hardware model can be set with ``model=modelname``.
-
- Use ``driver=help`` to list the available drivers,
- and ``model=help`` to list the available device types.
+``-audio [driver=]driver[,model=value][,prop[=value][,...]]``
+ If the ``model`` option is specified, ``-audio`` is a shortcut
+ for configuring both the guest audio hardware and the host audio
+ backend in one go. The guest hardware model can be set with
+ ``model=modelname``. Use ``model=help`` to list the available
+ device types.
The following two example do exactly the same, to show how ``-audio``
can be used to shorten the command line length:
|qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa
|qemu_system| -audio pa,model=sb16
+
+ If the ``model`` option is not specified, ``-audio`` is used to
+ configure a default audio backend that will be used whenever the
+ ``audiodev`` property is not set on a device or machine. In
+ particular, ``-audio none`` ensures that no audio is produced even
+ for machines that have embedded sound hardware.
+
+ In both cases, the driver option is the same as with the corresponding
+ ``-audiodev`` option below. Use ``driver=help`` to list the available
+ drivers.
+
ERST
DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
(on/off; default: off)
``discard-no-unref``
- When enabled, discards from the guest will not cause cluster
- allocations to be relinquished. This prevents qcow2 fragmentation
- that would be caused by such discards. Besides potential
+ When enabled, data clusters will remain preallocated when they are
+ no longer used, e.g. because they are discarded or converted to
+ zero clusters. As usual, whether the old data is discarded or kept
+ on the protocol level (i.e. in the image file) depends on the
+ setting of the pass-discard-request option. Keeping the clusters
+ preallocated prevents qcow2 fragmentation that would otherwise be
+ caused by freeing and re-allocating them later. Besides potential
performance degradation, such fragmentation can lead to increased
allocation of clusters past the end of the image file,
resulting in image files whose file length can grow much larger
OBP.
ERST
+#ifdef CONFIG_VNC
DEF("vnc", HAS_ARG, QEMU_OPTION_vnc ,
"-vnc <display> shorthand for -display vnc=<display>\n", QEMU_ARCH_ALL)
+#endif
SRST
``-vnc display[,option[,option[,...]]]``
Normally, if QEMU is compiled with graphical window support, it
DEF("initrd", HAS_ARG, QEMU_OPTION_initrd, \
"-initrd file use 'file' as initial ram disk\n", QEMU_ARCH_ALL)
SRST
+
``-initrd file``
Use file as initial ram disk.
``-initrd "file1 arg=foo,file2"``
This syntax is only available with multiboot.
- Use file1 and file2 as modules and pass arg=foo as parameter to the
- first module.
+ Use file1 and file2 as modules and pass ``arg=foo`` as parameter to the
+ first module. Commas can be provided in module parameters by doubling
+ them on the command line to escape them:
+
+``-initrd "bzImage earlyprintk=xen,,keep root=/dev/xvda1,initrd.img"``
+ Multiboot only. Use bzImage as the first module with
+ "``earlyprintk=xen,keep root=/dev/xvda1``" as its command line,
+ and initrd.img as the second module.
+
ERST
DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
" prepare for incoming migration, listen on\n" \
" specified protocol and socket address\n" \
"-incoming fd:fd\n" \
+ "-incoming file:filename[,offset=offset]\n" \
"-incoming exec:cmdline\n" \
" accept incoming migration on given file descriptor\n" \
" or from given external command\n" \
Prepare for incoming migration, listen on a given unix socket.
``-incoming fd:fd``
- Accept incoming migration from a given filedescriptor.
+ Accept incoming migration from a given file descriptor.
+
+``-incoming file:filename[,offset=offset]``
+ Accept incoming migration from a given file starting at offset.
+ offset allows the common size suffixes, or a 0x prefix, but not both.
``-incoming exec:cmdline``
Accept incoming migration as an output from specified external
they are specified. Note that the 'id' property must be set. These
objects are placed in the '/objects' path.
- ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,offset=offset,readonly=on|off``
+ ``-object memory-backend-file,id=id,size=size,mem-path=dir,share=on|off,discard-data=on|off,merge=on|off,dump=on|off,prealloc=on|off,host-nodes=host-nodes,policy=default|preferred|bind|interleave,align=align,offset=offset,readonly=on|off,rom=on|off|auto``
Creates a memory file backend object, which can be used to back
the guest RAM with huge pages.
The ``readonly`` option specifies whether the backing file is opened
read-only or read-write (default).
+ The ``rom`` option specifies whether to create Read Only Memory
+ (ROM) that cannot be modified by the VM. Any write attempts to such
+ ROM will be denied. Most use cases want proper RAM instead of ROM.
+ However, selected use cases, like R/O NVDIMMs, can benefit from
+ ROM. If set to ``on``, create ROM; if set to ``off``, create
+ writable RAM; if set to ``auto`` (default), the value of the
+ ``readonly`` option is used. This option is primarily helpful when
+ we want to have writable RAM in configurations that would
+ traditionally create ROM before the ``rom`` option was introduced:
+ VM templating, where we want to open a file readonly
+ (``readonly=on``) and mark the memory to be private for QEMU
+ (``share=off``). For this use case, we need writable RAM instead
+ of ROM, and want to also set ``rom=off``.
+
``-object memory-backend-ram,id=id,merge=on|off,dump=on|off,share=on|off,prealloc=on|off,size=size,host-nodes=host-nodes,policy=default|preferred|bind|interleave``
Creates a memory backend object, which can be used to back the
guest RAM. Memory backend objects offer more control than the
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