User:Paolo Bonzini/Machine init sequence

Basic phases

PHASE_NO_MACHINE

• Only backends can be created
• No machines have compat props that affect the backends, so that's good

QMP configuration flow starts here. machine-set command moves to the next step

PHASE_MACHINE_CREATED

• Backends can be connected to on-board devices (how?)

set-numa-options available here

accel-set (can only be invoked again if it fails) moves to the next step

PHASE_ACCEL_CREATED

• vl.c sets up memory here, but that's not required
• migration_object_init() can be called
• plugins can be loaded

CLI configuration flow starts here (preconfig enters the monitor here; w/o preconfig, x-exit-preconfig is invoked immediately)

accel-set actually goes directly from PHASE_MACHINE_CREATED to the next step

PHASE_MACHINE_INITIALIZED

• Devices can be created (including by x-exit-preconfig)

finish-machine-init, cont, migrate_incoming, x-exit-preconfig move to the next step

PHASE_MACHINE_READY

• everything after qdev_machine_creation_done()

New commands

Ccan be added to QEMU already:

• display-add (incl. -vnc, -spice)

New commands (specific to QMP configuration flow)

• machine-set (covers -M but also -smp, -boot, -m, -semihosting-config, maybe -cpu)
• accel-set (-accel)

Non-QemuOpts options

• -k (should have replacement property in -display curses / -display vnc)
• -uuid (should be added to -machine)
• -watchdog-action, -no-reboot, -no-shutdown (should be QemuOpts-ified as -action)

Other options without QMP equivalent

Move to "missing commands" as you see fit or remark on whether it's not needed in the QMP configuration flow:

• -acpitable
• -fsdev
• -fw_cfg
• -global
• -icount
• -iscsi (obsoleted by -blockdev?)
• -mon
• -option-rom
• -overcommit/-realtime
• -plugin (plugin-add?)
• -qtest (QOMify?)
• -rtc
• -replay
• -smbios
• -tpmdev

Current machine init sequence

Up to CHECKPOINT_INIT

• Runstate is RUN_STATE_PRECONFIG or RUN_STATE_INMIGRATE
• Get machine_class
• Set machine compat props
• set_memory_options
• Options: -global
• replay_configure
• Options: -rtc
• Option: -pidfile
• qemu_init_main_loop
• Options: -sandbox, -name, -add-fd
• current_machine is created
• Options: -trace, -L
• Options: -smp
• Options: -mem-prealloc (requires current_machine->smp.cpus, but could look at -smp cpus directly)
• Options: -plugin (requires -smp)
• Handle default devices
  • Default device check (needs machine_class)
  • A bunch of checks for -daemonize
  • Add default devices to device_configs
• Create backends
  • Create displays
  • Create early objects
  • Options: -spice
  • Create chardevs
  • Create fsdevs
  • Create audiodevs
• Machine properties set
• Accelerators created and properties set
• migration_object_init
  • Wants current_machine->enforce_config_section, but that part can be done later though
• Initialize qtest server (QOMify)
• Parse bootorder and -machine kernel_filename/initrd_filename/kernel_cmdline
• cpu_timers_init() (can be done earlier)
• Create default network (move with other device_configs operations)
• net_init_clients
• Create late objects
• blk_mig_init, ram_mig_init, dirty_bitmap_mig_init (move to migration_object_init())
• Create monitors (why so late?)
• Create backends for -serial/-parallel/-debugcon
• get_default_vga_model, select_vgahw, select_watchdog

After CHECKPOINT_INIT

• qdev_machine_init()
  • Only creates /machine/peripheral and /machine/peripheral-anon
• Determine ram_size
• parse_numa_opts() -> set_numa_options()
• Preconfig monitor
  • set_numa_options (same as -numa but more powerful)

RUN_STATE_PRELAUNCH

• machine_run_board_init(current_machine)
  • On-board devices are created
  • Requires accelerator to be initialized
• Devices cannot be realized before this point (buses don't exist)
• Start VM
  • loadvm or incoming migration
  • Otherwise, vm_start()

First attempt at cleaned up sequence

Early option parsing

• Runstate is RUN_STATE_PRELAUNCH or RUN_STATE_INMIGRATE
• Desugaring: -mem-prealloc, -watchdog
• Options: -pidfile, -sandbox, -name, -add-fd, -trace, -L, -incoming defer
• replay_configure

Early initialization

• qemu_init_main_loop()
• cpu_timers_init()

Command-line processing part one

• Options: -global, -rtc
• Get machine_class
• Set machine compat props
• Handle default devices
  • Default device check (needs machine_class but not MS)
  • A bunch of checks for -daemonize
  • Add default devices to device_configs
• Create default network
• Create backends
  • Create displays
  • Create early objects
  • Options: -spice
  • Create chardevs
  • Create fsdevs
  • Create audiodevs
• Initialize qtest server

Machine creation

• set_memory_options
• current_machine is created
  • qdev_machine_init()
• Options: -smp
• Machine properties set
  • set current_migration->send_configuration as in migration_object_init

Accelerator creation

• Accelerators created and properties set
• Parse bootorder and -machine kernel_filename/initrd_filename/kernel_cmdline
• migration_object_init()
  • blk_mig_init, ram_mig_init, dirty_bitmap_mig_init

Late creation

• Options: -boot
• net_init_clients
• Create late objects
• Create monitors
• Create backends for -serial/-parallel/-debugcon
• get_default_vga_model, select_vgahw, select_watchdog
• Determine ram_size
  • parse_numa_opts() -> set_numa_options()

Leaving preconfig

• CHECKPOINT_INIT
• Options: -plugin (requires -smp, but must be before CPUs are created)
• machine_run_board_init(current_machine)
  • On-board devices are created
  • Requires accelerator to be initialized
• Devices cannot be realized before this point (buses don't exist)
• cont/migrate_incoming/loadvm complete initialization of the machine
  • everything starting with cpu_synchronize_all_post_init