On 04/26/2018 09:39 AM, Igor Mammedov wrote: >>> I'll try to come up with a text for qemu-doc.texi, not about >>> deprecating -S but about when --preconfig should be used vs -S >>> and where to get list of commands that could be used at preconfig state. >> >> Sounds good to me. Thanks! > how about something like this: > > diff --git a/qemu-tech.texi b/qemu-tech.texi > index 52a56ae..6951258 100644 > --- a/qemu-tech.texi > +++ b/qemu-tech.texi > @@ -5,6 +5,7 @@ > * CPU emulation:: > * Translator Internals:: > * QEMU compared to other emulators:: > +* Managed start up options:: > * Bibliography:: > @end menu > > @@ -314,6 +315,44 @@ VirtualBox [9], Xen [10] and KVM [11] are based on QEMU. > QEMU-SystemC > [12] uses QEMU to simulate a system where some hardware devices are > developed in SystemC. > > +@node Managed start up options > +@section Managed start up options > + > +In system mode emulation, it's possible to create VM in paused state using > +-S command line option. In this state the machine is completely initialized > +according to command line options and ready to execute VM code but VCPU > threads > +are not executing any code. VM state in this paused state depends on way QEMU > +was started. It could be in: > +@table @asis > +@item initial state (after reset/power on state) > +@item with direct kernel loading initial state could be ammended to execute
s/ammended/amended/
> +code loaded by QEMU in VM's RAM and with incomming migration
s/incomming/incoming/
> +@item with incomming migrartion, initial state will by ammended by the
> migrated
and again, for both words
s/migrartion/migration/
> +machine state after migration completes.
> +@end table
> +
> +This paused state is typically used by users to query machine state and/or
> +additionally configure machine (hotplug devices) in runtime before allowing
> +VM code to run.
> +
> +However at -S pause point it's impossible to configure options that affect
> +initial VM creation (like: -smp/-m/-numa ...) or cold plug devices. That's
> +when -preconfig command line option should be used. It allows to pause
s/to pause/pausing/
> +QEMU before initial VM creation in preconfig state, query being created
> +VM at runtime and configure start up options depending on previous query
Reads awkwardly. Maybe:
It allows pausing QEMU before the initial VM creation, in a new
preconfig state, where additional queries and configuration can be
performed via QMP before moving on to the resulting configuration startup.
> +results. In preconfig state QEMU allows to configure VM only via QMP monitor
> +with a limited command set which doesn't depend on completely initialized
> +machine, which includes but not limited to:
In the preconfig state, QEMU only allows a limited set of commands over
the QMP monitor, where the commands do not depend on an initialized
machine, including but not limited to:
> +@table @asis
> +@item qmp_capabilities
> +@item query-qmp-schema
> +@item query-commands
> +@item query-status
> +@end table
> +The full list of commands is in QMP schema which could be queried with
> +query-qmp-schema, where commands supported at preconfig state have option
> +'allowed-in-preconfig' set to true.
> +
> @node Bibliography
> @section Bibliography
>
>> A separate command would have less room for ambiguity.
> I've added following instead of reusing 'cont':
>
> ##
>
> # @exit-preconfig:
>
This should definitely be mentioned in the docs section of commands
permitted during preconfig.
> #
>
> # Exit from "preconfig" state
>
> #
>
> # Since 2.13
>
> #
>
> # Returns: nothing
>
> #
>
> # Notes: Command makes QEMU exit from preconfig state and proceeds with
>
> # VM initialization using configuration data provided on command line
>
> # and via QMP monitor at preconfig state. Command is available only at
>
> # preconfig state (i.e. if --preconfig command line option).
>
> #
>
> # Example:
>
> #
>
> # -> { "execute": "exit-preconfig" }
>
> # <- { "return": {} }
>
> #
>
> ##
>
> { 'command': 'exit-preconfig', 'allowed-in-preconfig': true }
>
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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