1*2f4325dfSPeter MaydellManaged start up options 2*2f4325dfSPeter Maydell======================== 3*2f4325dfSPeter Maydell 4*2f4325dfSPeter MaydellIn system mode emulation, it's possible to create a VM in a paused 5*2f4325dfSPeter Maydellstate using the ``-S`` command line option. In this state the machine 6*2f4325dfSPeter Maydellis completely initialized according to command line options and ready 7*2f4325dfSPeter Maydellto execute VM code but VCPU threads are not executing any code. The VM 8*2f4325dfSPeter Maydellstate in this paused state depends on the way QEMU was started. It 9*2f4325dfSPeter Maydellcould be in: 10*2f4325dfSPeter Maydell 11*2f4325dfSPeter Maydell- initial state (after reset/power on state) 12*2f4325dfSPeter Maydell- with direct kernel loading, the initial state could be amended to execute 13*2f4325dfSPeter Maydell code loaded by QEMU in the VM's RAM and with incoming migration 14*2f4325dfSPeter Maydell- with incoming migration, initial state will be amended with the migrated 15*2f4325dfSPeter Maydell machine state after migration completes 16*2f4325dfSPeter Maydell 17*2f4325dfSPeter MaydellThis paused state is typically used by users to query machine state and/or 18*2f4325dfSPeter Maydelladditionally configure the machine (by hotplugging devices) in runtime before 19*2f4325dfSPeter Maydellallowing VM code to run. 20*2f4325dfSPeter Maydell 21*2f4325dfSPeter MaydellHowever, at the ``-S`` pause point, it's impossible to configure options 22*2f4325dfSPeter Maydellthat affect initial VM creation (like: ``-smp``/``-m``/``-numa`` ...) or 23*2f4325dfSPeter Maydellcold plug devices. The experimental ``--preconfig`` command line option 24*2f4325dfSPeter Maydellallows pausing QEMU before the initial VM creation, in a "preconfig" state, 25*2f4325dfSPeter Maydellwhere additional queries and configuration can be performed via QMP 26*2f4325dfSPeter Maydellbefore moving on to the resulting configuration startup. In the 27*2f4325dfSPeter Maydellpreconfig state, QEMU only allows a limited set of commands over the 28*2f4325dfSPeter MaydellQMP monitor, where the commands do not depend on an initialized 29*2f4325dfSPeter Maydellmachine, including but not limited to: 30*2f4325dfSPeter Maydell 31*2f4325dfSPeter Maydell- ``qmp_capabilities`` 32*2f4325dfSPeter Maydell- ``query-qmp-schema`` 33*2f4325dfSPeter Maydell- ``query-commands`` 34*2f4325dfSPeter Maydell- ``query-status`` 35*2f4325dfSPeter Maydell- ``x-exit-preconfig`` 36