" nvdimm=on|off controls NVDIMM support (default=off)\n"
" memory-encryption=@var{} memory encryption object to use (default=none)\n"
" hmat=on|off controls ACPI HMAT support (default=off)\n"
- " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n",
+ " memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
+ " cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n"
+ " zpcii-disable=on|off disables zPCI interpretation facilities (default=off)\n",
QEMU_ARCH_ALL)
SRST
``-machine [type=]name[,prop=value[,...]]``
-object memory-backend-ram,id=pc.ram,size=512M,x-use-canonical-path-for-ramblock-id=off
-machine memory-backend=pc.ram
-m 512M
+
+ ``cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]``
+ Define a CXL Fixed Memory Window (CFMW).
+
+ Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM.
+
+ They are regions of Host Physical Addresses (HPA) on a system which
+ may be interleaved across one or more CXL host bridges. The system
+ software will assign particular devices into these windows and
+ configure the downstream Host-managed Device Memory (HDM) decoders
+ in root ports, switch ports and devices appropriately to meet the
+ interleave requirements before enabling the memory devices.
+
+ ``targets.X=target`` provides the mapping to CXL host bridges
+ which may be identified by the id provied in the -device entry.
+ Multiple entries are needed to specify all the targets when
+ the fixed memory window represents interleaved memory. X is the
+ target index from 0.
+
+ ``size=size`` sets the size of the CFMW. This must be a multiple of
+ 256MiB. The region will be aligned to 256MiB but the location is
+ platform and configuration dependent.
+
+ ``interleave-granularity=granularity`` sets the granularity of
+ interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB
+ 4096KiB, 8192KiB and 16384KiB granularities supported.
+
+ Example:
+
+ ::
+
+ -machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512k
+
+ ``zpcii-disable=on|off``
+ Disables zPCI interpretation facilties on s390-ccw hosts.
+ This feature can be used to disable hardware virtual assists
+ related to zPCI devices. The default is off.
ERST
DEF("M", HAS_ARG, QEMU_OPTION_M,
" split-wx=on|off (enable TCG split w^x mapping)\n"
" tb-size=n (TCG translation block cache size)\n"
" dirty-ring-size=n (KVM dirty ring GFN count, default 0)\n"
+ " notify-vmexit=run|internal-error|disable,notify-window=n (enable notify VM exit and set notify window, x86 only)\n"
" thread=single|multi (enable multi-threaded TCG)\n", QEMU_ARCH_ALL)
SRST
``-accel name[,prop=value[,...]]``
is disabled (dirty-ring-size=0). When enabled, KVM will instead
record dirty pages in a bitmap.
+ ``notify-vmexit=run|internal-error|disable,notify-window=n``
+ Enables or disables notify VM exit support on x86 host and specify
+ the corresponding notify window to trigger the VM exit if enabled.
+ ``run`` option enables the feature. It does nothing and continue
+ if the exit happens. ``internal-error`` option enables the feature.
+ It raises a internal error. ``disable`` option doesn't enable the feature.
+ This feature can mitigate the CPU stuck issue due to event windows don't
+ open up for a specified of time (i.e. notify-window).
+ Default: notify-vmexit=run,notify-window=0.
+
ERST
DEF("smp", HAS_ARG, QEMU_OPTION_smp,
-numa hmat-cache,node-id=1,size=10K,level=1,associativity=direct,policy=write-back,line=8
ERST
-DEF("cxl-fixed-memory-window", HAS_ARG, QEMU_OPTION_cxl_fixed_memory_window,
- "-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]\n",
- QEMU_ARCH_ALL)
-SRST
-``-cxl-fixed-memory-window targets.0=firsttarget,targets.1=secondtarget,size=size[,interleave-granularity=granularity]``
- Define a CXL Fixed Memory Window (CFMW).
-
- Described in the CXL 2.0 ECN: CEDT CFMWS & QTG _DSM.
-
- They are regions of Host Physical Addresses (HPA) on a system which
- may be interleaved across one or more CXL host bridges. The system
- software will assign particular devices into these windows and
- configure the downstream Host-managed Device Memory (HDM) decoders
- in root ports, switch ports and devices appropriately to meet the
- interleave requirements before enabling the memory devices.
-
- ``targets.X=firsttarget`` provides the mapping to CXL host bridges
- which may be identified by the id provied in the -device entry.
- Multiple entries are needed to specify all the targets when
- the fixed memory window represents interleaved memory. X is the
- target index from 0.
-
- ``size=size`` sets the size of the CFMW. This must be a multiple of
- 256MiB. The region will be aligned to 256MiB but the location is
- platform and configuration dependent.
-
- ``interleave-granularity=granularity`` sets the granularity of
- interleave. Default 256KiB. Only 256KiB, 512KiB, 1024KiB, 2048KiB
- 4096KiB, 8192KiB and 16384KiB granularities supported.
-
- Example:
-
- ::
-
- -cxl-fixed-memory-window targets.0=cxl.0,targets.1=cxl.1,size=128G,interleave-granularity=512k
-
-ERST
-
DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
"-add-fd fd=fd,set=set[,opaque=opaque]\n"
" Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL)
(deprecated) environment variables.
ERST
+DEF("audio", HAS_ARG, QEMU_OPTION_audio,
+ "-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.
+
+ The following two example do exactly the same, to show how ``-audio``
+ can be used to shorten the command line length:
+
+ .. parsed-literal::
+
+ |qemu_system| -audiodev pa,id=pa -device sb16,audiodev=pa
+ |qemu_system| -audio pa,model=sb16
+ERST
+
DEF("audiodev", HAS_ARG, QEMU_OPTION_audiodev,
"-audiodev [driver=]driver,id=id[,prop[=value][,...]]\n"
" specifies the audio backend to use\n"
+ " Use ``-audiodev help`` to list the available drivers\n"
" id= identifier of the backend\n"
" timer-period= timer period in microseconds\n"
" in|out.mixing-engine= use mixing engine to mix streams inside QEMU\n"
"-audiodev sdl,id=id[,prop[=value][,...]]\n"
" in|out.buffer-count= number of buffers\n"
#endif
+#ifdef CONFIG_AUDIO_SNDIO
+ "-audiodev sndio,id=id[,prop[=value][,...]]\n"
+#endif
#ifdef CONFIG_SPICE
"-audiodev spice,id=id[,prop[=value][,...]]\n"
#endif
``in|out.buffer-count=count``
Sets the count of the buffers.
+``-audiodev sndio,id=id[,prop[=value][,...]]``
+ Creates a backend using SNDIO. This backend is available on
+ OpenBSD and most other Unix-like systems.
+
+ Sndio specific options are:
+
+ ``in|out.dev=device``
+ Specify the sndio device to use for input and/or output. Default
+ is ``default``.
+
+ ``in|out.latency=usecs``
+ Sets the desired period length in microseconds.
+
``-audiodev spice,id=id[,prop[=value][,...]]``
Creates a backend that sends audio through SPICE. This backend
requires ``-spice`` and automatically selected in that case, so
``qemu.wav``.
ERST
-DEF("soundhw", HAS_ARG, QEMU_OPTION_soundhw,
- "-soundhw c1,... enable audio support\n"
- " and only specified sound cards (comma separated list)\n"
- " use '-soundhw help' to get the list of supported cards\n"
- " use '-soundhw all' to enable all of them\n", QEMU_ARCH_ALL)
-SRST
-``-soundhw card1[,card2,...] or -soundhw all``
- Enable audio and selected sound hardware. Use 'help' to print all
- available sound hardware. For example:
-
- .. parsed-literal::
-
- |qemu_system_x86| -soundhw sb16,adlib disk.img
- |qemu_system_x86| -soundhw es1370 disk.img
- |qemu_system_x86| -soundhw ac97 disk.img
- |qemu_system_x86| -soundhw hda disk.img
- |qemu_system_x86| -soundhw all disk.img
- |qemu_system_x86| -soundhw help
-
- Note that Linux's i810\_audio OSS kernel (for AC97) module might
- require manually specifying clocking.
-
- ::
-
- modprobe i810_audio clocking=48000
-ERST
-
DEF("device", HAS_ARG, QEMU_OPTION_device,
"-device driver[,prop[=value][,...]]\n"
" add device (based on driver)\n"
DEFHEADING(Block device options:)
+SRST
+The QEMU block device handling options have a long history and
+have gone through several iterations as the feature set and complexity
+of the block layer have grown. Many online guides to QEMU often
+reference older and deprecated options, which can lead to confusion.
+
+The recommended modern way to describe disks is to use a combination of
+``-device`` to specify the hardware device and ``-blockdev`` to
+describe the backend. The device defines what the guest sees and the
+backend describes how QEMU handles the data.
+
+ERST
+
DEF("fda", HAS_ARG, QEMU_OPTION_fda,
"-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL)
DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)
Use file as SecureDigital card image.
ERST
-DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
- "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
-SRST
-``-pflash file``
- Use file as a parallel flash image.
-ERST
-
DEF("snapshot", 0, QEMU_OPTION_snapshot,
"-snapshot write to temporary files instead of disk image files\n",
QEMU_ARCH_ALL)
"-display spice-app[,gl=on|off]\n"
#endif
#if defined(CONFIG_SDL)
- "-display sdl[,alt_grab=on|off][,ctrl_grab=on|off][,gl=on|core|es|off]\n"
- " [,grab-mod=<mod>][,show-cursor=on|off][,window-close=on|off]\n"
+ "-display sdl[,gl=on|core|es|off][,grab-mod=<mod>][,show-cursor=on|off]\n"
+ " [,window-close=on|off]\n"
#endif
#if defined(CONFIG_GTK)
"-display gtk[,full-screen=on|off][,gl=on|off][,grab-on-hover=on|off]\n"
- " [,show-cursor=on|off][,window-close=on|off]\n"
+ " [,show-tabs=on|off][,show-cursor=on|off][,window-close=on|off]\n"
+ " [,show-menubar=on|off]\n"
#endif
#if defined(CONFIG_VNC)
"-display vnc=<display>[,<optargs>]\n"
, QEMU_ARCH_ALL)
SRST
``-display type``
- Select type of display to use. This option is a replacement for the
- old style -sdl/-curses/... options. Use ``-display help`` to list
- the available display types. Valid values for type are
+ Select type of display to use. Use ``-display help`` to list the available
+ display types. Valid values for type are
``spice-app[,gl=on|off]``
Start QEMU as a Spice server and launch the default Spice client
the mouse grabbing in conjunction with the "g" key. ``<mods>`` can be
either ``lshift-lctrl-lalt`` or ``rctrl``.
- ``alt_grab=on|off`` : Use Control+Alt+Shift-g to toggle mouse grabbing.
- This parameter is deprecated - use ``grab-mod`` instead.
-
- ``ctrl_grab=on|off`` : Use Right-Control-g to toggle mouse grabbing.
- This parameter is deprecated - use ``grab-mod`` instead.
-
``gl=on|off|core|es`` : Use OpenGL for displaying
``show-cursor=on|off`` : Force showing the mouse cursor
``grab-on-hover=on|off`` : Grab keyboard input on mouse hover
+ ``show-tabs=on|off`` : Display the tab bar for switching between the
+ various graphical interfaces (e.g. VGA and
+ virtual console character devices) by default.
+
``show-cursor=on|off`` : Force showing the mouse cursor
``window-close=on|off`` : Allow to quit qemu with window close button
+ ``show-menubar=on|off`` : Display the main window menubar, defaults to "on"
+
``curses[,charset=<encoding>]``
Display video output via curses. For graphics device models
which support a text mode, QEMU can display this output using a
Use C-a h for help on switching between the console and monitor.
ERST
-DEF("curses", 0, QEMU_OPTION_curses,
- "-curses shorthand for -display curses\n",
- QEMU_ARCH_ALL)
-SRST
-``-curses``
- Normally, if QEMU is compiled with graphical window support, it
- displays output such as guest graphics, guest console, and the QEMU
- monitor in a window. With this option, QEMU can display the VGA
- output when in text mode using a curses/ncurses interface. Nothing
- is displayed in graphical mode.
-ERST
-
-DEF("alt-grab", 0, QEMU_OPTION_alt_grab,
- "-alt-grab use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt)\n",
- QEMU_ARCH_ALL)
-SRST
-``-alt-grab``
- Use Ctrl-Alt-Shift to grab mouse (instead of Ctrl-Alt). Note that
- this also affects the special keys (for fullscreen, monitor-mode
- switching, etc). This option is deprecated - please use
- ``-display sdl,grab-mod=lshift-lctrl-lalt`` instead.
-ERST
-
-DEF("ctrl-grab", 0, QEMU_OPTION_ctrl_grab,
- "-ctrl-grab use Right-Ctrl to grab mouse (instead of Ctrl-Alt)\n",
- QEMU_ARCH_ALL)
-SRST
-``-ctrl-grab``
- Use Right-Ctrl to grab mouse (instead of Ctrl-Alt). Note that this
- also affects the special keys (for fullscreen, monitor-mode
- switching, etc). This option is deprecated - please use
- ``-display sdl,grab-mod=rctrl`` instead.
-ERST
-
-DEF("sdl", 0, QEMU_OPTION_sdl,
- "-sdl shorthand for -display sdl\n", QEMU_ARCH_ALL)
-SRST
-``-sdl``
- Enable SDL.
-ERST
-
#ifdef CONFIG_SPICE
DEF("spice", HAS_ARG, QEMU_OPTION_spice,
"-spice [port=port][,tls-port=secured-port][,x509-dir=<dir>]\n"
" [,asset=str][,part=str][,max-speed=%d][,current-speed=%d]\n"
" [,processor-id=%d]\n"
" specify SMBIOS type 4 fields\n"
+ "-smbios type=8[,external_reference=str][,internal_reference=str][,connector_type=%d][,port_type=%d]\n"
+ " specify SMBIOS type 8 fields\n"
"-smbios type=11[,value=str][,path=filename]\n"
" specify SMBIOS type 11 fields\n"
"-smbios type=17[,loc_pfx=str][,bank=str][,manufacturer=str][,serial=str]\n"
#ifdef __linux__
"-netdev vhost-vdpa,id=str,vhostdev=/path/to/dev\n"
" configure a vhost-vdpa network,Establish a vhost-vdpa netdev\n"
+#endif
+#ifdef CONFIG_VMNET
+ "-netdev vmnet-host,id=str[,isolated=on|off][,net-uuid=uuid]\n"
+ " [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
+ " configure a vmnet network backend in host mode with ID 'str',\n"
+ " isolate this interface from others with 'isolated',\n"
+ " configure the address range and choose a subnet mask,\n"
+ " specify network UUID 'uuid' to disable DHCP and interact with\n"
+ " vmnet-host interfaces within this isolated network\n"
+ "-netdev vmnet-shared,id=str[,isolated=on|off][,nat66-prefix=addr]\n"
+ " [,start-address=addr,end-address=addr,subnet-mask=mask]\n"
+ " configure a vmnet network backend in shared mode with ID 'str',\n"
+ " configure the address range and choose a subnet mask,\n"
+ " set IPv6 ULA prefix (of length 64) to use for internal network,\n"
+ " isolate this interface from others with 'isolated'\n"
+ "-netdev vmnet-bridged,id=str,ifname=name[,isolated=on|off]\n"
+ " configure a vmnet network backend in bridged mode with ID 'str',\n"
+ " use 'ifname=name' to select a physical network interface to be bridged,\n"
+ " isolate this interface from others with 'isolated'\n"
#endif
"-netdev hubport,id=str,hubid=n[,netdev=nd]\n"
" configure a hub port on the hub with ID 'n'\n", QEMU_ARCH_ALL)
#endif
#ifdef CONFIG_POSIX
"vhost-user|"
+#endif
+#ifdef CONFIG_VMNET
+ "vmnet-host|vmnet-shared|vmnet-bridged|"
#endif
"socket][,option][,...][mac=macaddr]\n"
" initialize an on-board / default host NIC (using MAC address\n"
#endif
#ifdef CONFIG_NETMAP
"netmap|"
+#endif
+#ifdef CONFIG_VMNET
+ "vmnet-host|vmnet-shared|vmnet-bridged|"
#endif
"socket][,option][,option][,...]\n"
" old way to initialize a host network interface\n"
#endif
-DEFHEADING(Linux/Multiboot boot specific:)
+DEFHEADING(Boot Image or Kernel specific:)
SRST
-When using these options, you can use a given Linux or Multiboot kernel
-without installing it in the disk image. It can be useful for easier
-testing of various kernels.
+There are broadly 4 ways you can boot a system with QEMU.
+ - specify a firmware and let it control finding a kernel
+ - specify a firmware and pass a hint to the kernel to boot
+ - direct kernel image boot
+ - manually load files into the guest's address space
+
+The third method is useful for quickly testing kernels but as there is
+no firmware to pass configuration information to the kernel the
+hardware must either be probeable, the kernel built for the exact
+configuration or passed some configuration data (e.g. a DTB blob)
+which tells the kernel what drivers it needs. This exact details are
+often hardware specific.
+
+The final method is the most generic way of loading images into the
+guest address space and used mostly for ``bare metal`` type
+development where the reset vectors of the processor are taken into
+account.
+
+ERST
+
+SRST
+
+For x86 machines and some other architectures ``-bios`` will generally
+do the right thing with whatever it is given. For other machines the
+more strict ``-pflash`` option needs an image that is sized for the
+flash device for the given machine type.
+
+Please see the :ref:`system-targets-ref` section of the manual for
+more detailed documentation.
+
+ERST
+
+DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
+ "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
+SRST
+``-bios file``
+ Set the filename for the BIOS.
+ERST
+
+DEF("pflash", HAS_ARG, QEMU_OPTION_pflash,
+ "-pflash file use 'file' as a parallel flash image\n", QEMU_ARCH_ALL)
+SRST
+``-pflash file``
+ Use file as a parallel flash image.
+ERST
+
+SRST
+
+The kernel options were designed to work with Linux kernels although
+other things (like hypervisors) can be packaged up as a kernel
+executable image. The exact format of a executable image is usually
+architecture specific.
+
+The way in which the kernel is started (what address it is loaded at,
+what if any information is passed to it via CPU registers, the state
+of the hardware when it is started, and so on) is also architecture
+specific. Typically it follows the specification laid down by the
+Linux kernel for how kernels for that architecture must be started.
ERST
kernel on boot.
ERST
+SRST
+
+Finally you can also manually load images directly into the address
+space of the guest. This is most useful for developers who already
+know the layout of their guest and take care to ensure something sane
+will happen when the reset vector executes.
+
+The generic loader can be invoked by using the loader device:
+
+``-device loader,addr=<addr>,data=<data>,data-len=<data-len>[,data-be=<data-be>][,cpu-num=<cpu-num>]``
+
+there is also the guest loader which operates in a similar way but
+tweaks the DTB so a hypervisor loaded via ``-kernel`` can find where
+the guest image is:
+
+``-device guest-loader,addr=<addr>[,kernel=<path>,[bootargs=<arguments>]][,initrd=<path>]``
+
+ERST
+
DEFHEADING()
DEFHEADING(Debug/Expert options:)
To list all the data directories, use ``-L help``.
ERST
-DEF("bios", HAS_ARG, QEMU_OPTION_bios, \
- "-bios file set the filename for the BIOS\n", QEMU_ARCH_ALL)
-SRST
-``-bios file``
- Set the filename for the BIOS.
-ERST
-
DEF("enable-kvm", 0, QEMU_OPTION_enable_kvm, \
"-enable-kvm enable KVM full virtualization support\n",
QEMU_ARCH_ARM | QEMU_ARCH_I386 | QEMU_ARCH_MIPS | QEMU_ARCH_PPC |
" action when guest reboots [default=reset]\n"
"-action shutdown=poweroff|pause\n"
" action when guest shuts down [default=poweroff]\n"
- "-action panic=pause|shutdown|none\n"
+ "-action panic=pause|shutdown|exit-failure|none\n"
" action when guest panics [default=shutdown]\n"
"-action watchdog=reset|shutdown|poweroff|inject-nmi|pause|debug|none\n"
" action when watchdog fires [default=reset]\n",
``-action panic=none``
``-action reboot=shutdown,shutdown=pause``
- ``-watchdog i6300esb -action watchdog=pause``
+ ``-device i6300esb -action watchdog=pause``
ERST
specifies the snapshot name used to load the initial VM state.
ERST
-DEF("watchdog", HAS_ARG, QEMU_OPTION_watchdog, \
- "-watchdog model\n" \
- " enable virtual hardware watchdog [default=none]\n",
- QEMU_ARCH_ALL)
-SRST
-``-watchdog model``
- Create a virtual hardware watchdog device. Once enabled (by a guest
- action), the watchdog must be periodically polled by an agent inside
- the guest or else the guest will be restarted. Choose a model for
- which your guest has drivers.
-
- The model is the model of hardware watchdog to emulate. Use
- ``-watchdog help`` to list available hardware models. Only one
- watchdog can be enabled for a guest.
-
- The following models may be available:
-
- ``ib700``
- iBASE 700 is a very simple ISA watchdog with a single timer.
-
- ``i6300esb``
- Intel 6300ESB I/O controller hub is a much more featureful
- PCI-based dual-timer watchdog.
-
- ``diag288``
- A virtual watchdog for s390x backed by the diagnose 288
- hypercall (currently KVM only).
-ERST
-
DEF("watchdog-action", HAS_ARG, QEMU_OPTION_watchdog_action, \
"-watchdog-action reset|shutdown|poweroff|inject-nmi|pause|debug|none\n" \
" action when watchdog fires [default=reset]\n",
Examples:
- ``-watchdog i6300esb -watchdog-action pause``; \ ``-watchdog ib700``
+ ``-device i6300esb -watchdog-action pause``
ERST
information about the facilities this enables.
ERST
DEF("semihosting-config", HAS_ARG, QEMU_OPTION_semihosting_config,
- "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]\n" \
+ "-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]\n" \
" semihosting configuration\n",
QEMU_ARCH_ARM | QEMU_ARCH_M68K | QEMU_ARCH_XTENSA |
QEMU_ARCH_MIPS | QEMU_ARCH_NIOS2 | QEMU_ARCH_RISCV)
SRST
-``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,arg=str[,...]]``
+``-semihosting-config [enable=on|off][,target=native|gdb|auto][,chardev=id][,userspace=on|off][,arg=str[,...]]``
Enable and configure semihosting (ARM, M68K, Xtensa, MIPS, Nios II, RISC-V
only).
Send the output to a chardev backend output for native or auto
output when not in gdb
+ ``userspace=on|off``
+ Allows code running in guest userspace to access the semihosting
+ interface. The default is that only privileged guest code can
+ make semihosting calls. Note that setting ``userspace=on`` should
+ only be used if all guest code is trusted (for example, in
+ bare-metal test case code).
+
``arg=str1,arg=str2,...``
Allows the user to pass input arguments, and can be used
multiple times to build up a list. The old-style