[vbox-dev] Change setting with java Main API

[Maxime Dor]

You are correct, lunchVMPRocess() starts a front-end, so the Write lock
(which is exclusive) is not owned by you, but by the process of the front
end.
Some settings can be changed during runtime, and you only need a Shared
Lock for those (network interface attachment per exemple). Last time I
asked the devs, there was no exhaustive list of the settings that can be
changed with Shared lock. So you need to rely on the existing behaviour of
the Virtualbox Manager to know.

Be aware that a bug exist that allow you to still save all the settings
with the Java API (at least) : https://www.virtualbox.org/ticket/12164 - so
you can't just try & see which settings fails, they will all succeed.
Writing your own front-end will not help because the limitation of changing
the settings at runtime is because some are simply not taken into account
until you start the VM, like the amount of CPU or the amount of RAM. Even
if you wrote your own front-end and changed the values, they wouldn't be
taken into account before a poweroff & poweron of the VM.
I would not recommend writting your own front-end since you can use the
Shared lock to save settings.


On 30 May 2014 11:59, Federica Renzi <renzi.fede at gmail.com> wrote:

> Errata corrige: I use launchVMProcess() method to start up the machine
> with a frontend, so It will be that frontend the lock owner on machine,
> isn't it?
>
> Let me see if I completely understood:
> The only way to change setting (and make them effective) during runtime is
> to have write lock on my machine and I can't do it starting up the machine
> using an existing frontend...right?
> If it is correct, I will have to write my own frontend...
>
> Sorry for these questions but I'm newbie and VirtualBox is...huge!:-)
>
>
> 2014-05-30 9:07 GMT+02:00 Federica Renzi <renzi.fede at gmail.com>:
>
> thanks for your response!
>> Well...I tried to use LockType.Shared but It doesn't let me to save
>> setting ( The function "saveSettings" returned an error condition: "The
>> machine is not mutable (state is Running)")
>>
>> Yes, The machine is running under my control (in theory), because I
>> started it up using java Main Api.
>> I really would like to change some setting while it is running but I
>> don't understand if it's possible.
>>
>>
>>
>> 2014-05-29 22:07 GMT+02:00 Maxime Dor <maxime.dor at altherian.org>:
>>
>> Use LockType.Shared instead - some other process must already be using
>>> the VM (is it running?)
>>>
>>>
>>> On 29 May 2014 10:12, Federica Renzi <renzi.fede at gmail.com> wrote:
>>>
>>>>  Hi everyone,
>>>> I'm trying to change some VM setting during the execution of
>>>> virtualbox. I read in SDK documentation that it's possible only locking the
>>>> machine and saving its state, otherwise no change will be performed.
>>>>
>>>> I tried to achieve it using java api (com-xpcom glue) and custumize
>>>> TestVBox.java, but I fall into these errors:
>>>>
>>>>    - if I write
>>>>    m.lockMachine(sess, LockType.fromValue(2)); // lock write
>>>>    The function "lockMachine" returned an error condition: "The
>>>>    machine 'NAME' is already locked for a session (or being unlocked)"
>>>>    (0x80bb0007)
>>>>
>>>>    - if I write
>>>>    sess.unlockMachine();
>>>>    The function "unlockMachine" returned an error condition: "The
>>>>    session is not locked (session state: Unlocked)" (0x8000ffff)
>>>>
>>>>    - if I write directly (without any lock command)
>>>>    m.saveSettings();
>>>>    The function "saveSettings" returned an error condition: "The
>>>>    machine is not mutable (state is Running)" (0x80bb0002)
>>>>
>>>>
>>>> How could I solve it?
>>>>
>>>> Thanks
>>>>
>>>> --
>>>> Federica Renzi
>>>>
>>>> _______________________________________________
>>>> vbox-dev mailing list
>>>> vbox-dev at virtualbox.org
>>>> https://www.virtualbox.org/mailman/listinfo/vbox-dev
>>>>
>>>>
>>>
>>
>>
>> --
>> Federica Renzi
>>
>
>
>
> --
> Federica Renzi
>
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