User:Paolo Bonzini/Machine init sequence

Tasks

Clean up global variables (bios_name, ram_size) [Paolo]
Clean up qemu_init [Paolo]
Convert -machine, -object, -accel from QemuOpts to keyval [Paolo]
Deprecate x-exit-preconfig, replacing it with cont/finish-machine-init/loadvm/migrate_incoming [Paolo]
Split reusable parts of vl.c [Paolo]
Replace -m, -smp, -boot, -semihosting-config, -rtc with machine properties
Add machine-set and accel-set commands

Independent pieces:

Add QOM replacement for -qtest, "-object qtest,chardev=..."
QAPIfy -display, add "-display add".
Make more commands available in preconfig (e.g. object-add, netdev-add, blockdev-add)

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

Specific to QMP configuration flow:

machine-set (covers -M but also -smp, -boot, -m, -semihosting-config, -acpitable, -smbios, maybe -cpu)
accel-set (-accel)
something to replace -incoming defer??

Non-QemuOpts options

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

Other command line 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:

-display
-fsdev
-fw_cfg
-global
-icount
-iscsi (obsoleted by -blockdev?)
-mon
-msg
-option-rom
-overcommit/-realtime
-plugin (plugin-add?)
-qtest (QOMify?)
-rtc
-replay
-tpmdev
-dump-vmstate

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