The monitor

QEMU's human monitor: every command and info subcommand, answered in QEMU's words, at the (wemu) prompt.

The human monitor (HMP) is QEMU's text console for a running machine. Every command and info subcommand of QEMU 11.1 is known; this page lists what each does here.

Opening the monitor

In a terminal: with -nographic, press Ctrl+A then c to switch between the guest's console and the monitor. -monitor stdio puts the monitor on the terminal from the start. The prompt is (wemu).
From JavaScript: vm.hmp(line) runs one command and resolves with its output.
Over QMP: human-monitor-command with {"command-line": "info status"}.

(wemu) info status
VM status: running
(wemu) savevm clean
(wemu) x /4xg $sp

help (or ?) lists every command with a one-line description; info alone lists the subcommands.

Note Leave a space between a command and its format: x /8xg $sp, not x/8xg $sp.

Run control

Command	Description
`stop`, `s`	Pause the machine.
`cont`, `c`	Resume it.
`system_reset`	Reset it.
`system_powerdown`	Press the power button.
`quit`, `q`	Stop and release the machine.

Command	Description
`savevm TAG`	Save the whole machine under `TAG`.
`loadvm TAG`	Restore it.
`delvm TAG`	Delete it.
`info snapshots`	List the snapshots.
`migrate [-d] file:PATH`	Save the machine's state to a file. `-d` is accepted; the command returns when the file is written either way.
`migrate_incoming file:PATH`	Load a state into a machine started with `-incoming defer`.
`migrate_set_capability CAP on\|off`, `migrate_set_parameter NAME VALUE`	Accepted and stored.

Memory and registers

`x` and `xp`

x /FMT ADDRESS      guest virtual memory, as core 0 sees it now
xp /FMT ADDRESS     guest physical memory (RAM)

FMT is /[count][format][size]:

Part	Values	Default
count	how many units	1
format	`x` hex, `d` signed decimal, `u` unsigned decimal, `o` octal, `c` character, `i` instruction words	`x`
size	`b` 1 byte, `h` 2, `w` 4, `g` 8	`w`

The last format used is remembered. Rows hold 8 bytes for byte units and 16 bytes otherwise; a row that can't be read prints Cannot access memory and ends the dump.

(wemu) xp /4xw 0x40000000     # four 32-bit words at the start of RAM, in hex
(wemu) x /8xb $pc             # eight bytes at the current instruction
(wemu) x /2dg $sp             # two 64-bit signed values on the stack

Note There is no disassembler: /i prints each instruction as its 32-bit word.

`print` and `p`

print /FMT EXPRESSION

Evaluates an expression and prints it in hex (or the given format). Expressions take numbers (0x… hex, a leading 0 for octal, decimal), the registers $pc, $sp, $x0 to $x30 and $el, parentheses, and C's operators + - * / % & | ^ ~ << >>.

(wemu) p $sp + 0x10           # an address, in hex
(wemu) p /d $x0               # a register, in decimal

Other memory commands

Command	Description
`info registers`	Core 0's `X0` to `X30`.
`gva2gpa ADDRESS`	Translate a virtual address to a physical one.
`sum ADDRESS SIZE`	A checksum of physical memory.
`memsave ADDRESS SIZE FILE`	Save virtual memory to a file.
`pmemsave ADDRESS SIZE FILE`	Save physical memory to a file.
`dump-guest-memory FILE`	An ELF core of the guest's RAM. `-p` (a paging dump) is refused: `paging dumps are not available here`.
`dumpdtb FILE`	The device tree the guest booted with.
`info mem`, `info mtree`	The RAM's address range.

Input and display

Command	Description
`sendkey KEYS [HOLD_MS]`	Press keys together, joined by `-`: `sendkey ctrl-alt-delete`.
`mouse_move DX DY [DZ]`	Move the pointer; `DZ` turns the wheel.
`mouse_button STATE`	Set the buttons: 1 left, 2 middle, 4 right.
`screendump FILE [-f png]`	Save the screen as PPM, or PNG.
`info mice`	The pointing devices.

Devices

Command	Description
`info block`	The disks.
`info blockstats`	Disk counters.
`info network`	The network cards and their backends.
`set_link NAME on\|off`	A network card's link.
`info usb`	The USB devices.
`info pci`	The PCI functions.
`info chardev`	The character devices.
`ringbuf_write DEVICE DATA`, `ringbuf_read DEVICE SIZE`	A ring-buffer console.
`info qtree`, `info qom-tree`, `qom-list`, `qom-get`	The device tree.
`info virtio`	The virtio devices.

Sound

Command	Description
`wavcapture PATH [FREQUENCY [BITS [CHANNELS]]]`	Record what the guest plays to a WAV file.
`stopcapture`	Stop recording and write the file.
`info capture`	The recording in progress.

Information

Subcommand	Shows
`info status`	The run state.
`info version`	`11.1.50 (warm64 0.1.0)`
`info name`, `info uuid`	The `-name` and `-uuid`.
`info cpus`	The cores.
`info kvm`	`kvm support: disabled`
`info accel`	`tcg`
`info jit`	The JIT's counters.
`info irq`, `info pic`	The interrupt controller.
`info roms`	The kernel image loaded.
`info migrate`	The last migration.
`info memory_size_summary`	The RAM size.

Every command

Every command and alias of QEMU 11.1's monitor is known. Those not described above:

More commands that work

Command	Description
`help [COMMAND]`, `?`	List the commands.
`cpu INDEX`	Choose the CPU the memory commands use. Accepted; they use core 0.
`gpa2hva ADDRESS`	Where a physical address lies in the machine's RAM.
`i /FMT PORT`, `o /FMT PORT VALUE`	Read and write an I/O port. The board has no I/O port space, so reads return all ones.
`mouse_set INDEX`	Choose the pointing device. There is one.
`chardev-send-break ID`	Send a serial break.
`announce_self`	Announce the network cards.
`migrate_cancel`	Cancel a migration.
`log ITEMS`, `logfile FILE`, `trace-file`, `one-insn-per-tb`, `sync-profile`	Accepted, with no effect.
`watchdog_action ACTION`, `migration_mode MODE`, `calc_dirty_rate`, `nbd_server_stop`, `clear`	Accepted, with no effect.

Commands refused

These answer as QEMU does on a machine without the feature:

Commands	Why
`device_add`, `device_del`, `drive_add`, `drive_del`, `netdev_add`, `netdev_del`, `object_add`, `object_del`, `chardev-add`, `chardev-change`, `chardev-remove`	No hot-plug: name devices on the command line.
`eject [-f] DEVICE`, `change`	Disks aren't removable, with or without `-f`.
`block_resize`, `block_set_io_throttle`	Disks are fixed while the machine runs.
`commit`, `block_stream`, `snapshot_blkdev`, `snapshot_blkdev_internal`, `snapshot_delete_blkdev_internal`, `drive_mirror`, `drive_backup`	Raw images have no backing files, internal snapshots or jobs.
`block_job_set_speed`, `block_job_cancel`, `block_job_complete`, `block_job_pause`, `block_job_resume`	No block jobs.
`nbd_server_start`, `nbd_server_add`, `nbd_server_remove`	No NBD server.
`wemu-io`, `qemu-io`	The disks are the host's images.
`migrate_continue`, `migrate_recover`, `migrate_pause`, `migrate_start_postcopy`	No postcopy migration.
`system_wakeup`	Guests can't suspend here.
`nmi`	The machine has no NMIs.
`gpa2hpa`	The host is WebAssembly: there's no host physical address.
`hostfwd_add`, `hostfwd_remove`	The user network has no port forwarding.
`set_password`, `expire_password`, `client_migrate_info`	No VNC or SPICE.
`gdbserver`	No gdb stub.
`replay_break`, `replay_delete_break`, `replay_seek`	Record and replay are off.
`set_vcpu_dirty_limit`, `cancel_vcpu_dirty_limit`	Needs KVM.
`getfd`, `closefd`	No file descriptors are passed to the monitor.
`trace-event NAME on\|off`	No trace events: `No trace events found matching 'NAME'`.
`qom-set`	Properties are read-only.
`boot_set`	The boot order can't change while running.
`balloon`	No balloon device.
`exit_preconfig`	Only in QEMU's preconfig state.
`pcie_aer_inject_error`, `mce`, `dump-skeys`, `x_colo_lost_heartbeat`, `xen-event-inject`, `xen-event-list`	Other platforms' and features' commands.

Every info subcommand

Subcommand	Shows
`info status`, `info version`, `info name`, `info uuid`	The run state, version, name and UUID.
`info cpus`, `info hotpluggable-cpus`	The cores.
`info registers`	Core 0's `X0` to `X30`.
`info kvm`, `info accel`, `info accelerators`	`kvm support: disabled`; `tcg`.
`info jit`	The JIT's counters.
`info irq`, `info pic`	The interrupt controller.
`info mem`, `info mtree`, `info ramblock`, `info memory_size_summary`	The RAM.
`info numa`	`0 nodes`
`info roms`	The kernel image loaded.
`info block`, `info blockstats`, `info block-jobs`	The disks, their counters, and (none) block jobs.
`info network`, `info usernet`	The network cards and the user network.
`info usb`, `info pci`, `info virtio`, `info mice`	The devices.
`info chardev`	The character devices.
`info qtree`, `info qdm`, `info qom-tree`	The device tree, the device models, the object tree.
`info snapshots`	The snapshots.
`info migrate`, `info migrate_capabilities`, `info migrate_parameters`	The last migration and its settings.
`info dump`	The last `dump-guest-memory`.
`info capture`	The sound recording in progress.
`info vnc`, `info spice`	`Server: disabled`
`info tpm`	`TPM device not supported`
`info replay`	`Record/replay is not active`
`info dirty_rate`, `info vcpu_dirty_limit`	Not measured.
`info sync-profile`	`sync-profile is not enabled`
`info history`, `info tlb`, `info lapic`, `info usbhost`, `info trace-events`, `info memdev`, `info memory-devices`, `info iothreads`, `info stats`, `info cryptodev`, `info rocker-ports`	Empty: the machine has none.
`info sev`, `info sgx`, `info via`	`SEV is not available on this machine`, and likewise.
`info balloon`, `info firmware-log`	Refused: no balloon device, no firmware log.
`info vm-generation-id`	Refused: `VM Generation ID device not found`.
`info rocker`, `info rocker-of-dpa-flows`, `info rocker-of-dpa-groups`	Refused: `rocker NAME not found`.
`info virtio-status`, `info virtio-queue-status`, `info virtio-vhost-queue-status`, `info virtio-queue-element`	Refused: `Path PATH is not a VirtIODevice`.
`info skeys`, `info cmma`	Refused: `this is only available on s390x guests`.

The monitor

Opening the monitor

Run control

Snapshots and migration

Memory and registers

`x` and `xp`

`print` and `p`

Other memory commands

Input and display

Devices

Sound

Information

Every command

More commands that work

Commands refused

Every info subcommand

See also