[Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Paolo Bonzini]

On 12/07/2009 01:42 PM, Gerd Hoffmann wrote:
> Add global command line option to disable default devices.

Should -readconfig imply this?

Paolo

Re: [Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Gerd Hoffmann]

On 12/08/09 13:46, Paolo Bonzini wrote:
> On 12/07/2009 01:42 PM, Gerd Hoffmann wrote:
>> Add global command line option to disable default devices.
>
> Should -readconfig imply this?

Hmm, not sure.  Why do you think this would be useful?

cheers,
   Gerd

Re: [Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Paolo Bonzini]

> > > Add global command line option to disable default devices.
> >
> > Should -readconfig imply this?
> 
> Hmm, not sure.  Why do you think this would be useful?

Here is my thinking: if you used -writeconfig, your machine description
is (at least in theory) entirely included in the config file including
(again in theory) the default devices.  So, if the machine description
has no parallel port, QEMU should not create a default one when you load
it with -readconfig.

It's not really about usefulness in other words; it's more whether you
think it fits in -{read,write}config's design or not.

Paolo

Re: [Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Daniel P. Berrange]

On Tue, Dec 08, 2009 at 11:11:29AM -0500, Paolo Bonzini wrote:
> > > > Add global command line option to disable default devices.
> > >
> > > Should -readconfig imply this?
> > 
> > Hmm, not sure.  Why do you think this would be useful?
> 
> Here is my thinking: if you used -writeconfig, your machine description
> is (at least in theory) entirely included in the config file including
> (again in theory) the default devices.  So, if the machine description
> has no parallel port, QEMU should not create a default one when you load
> it with -readconfig.

Shouldn't  -writeconfig just  add '-nodefaults' to the config it
generates ?

That way if someone instead creates a configfile by hand, copying in
their existing QEMU args they still get default devices which matches 
behaviour of their existing CLI args.

Regards,
Daniel
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Re: [Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Gerd Hoffmann]

On 12/08/09 17:11, Paolo Bonzini wrote:
>>>> Add global command line option to disable default devices.
>>>
>>> Should -readconfig imply this?
>>
>> Hmm, not sure.  Why do you think this would be useful?
>
> Here is my thinking: if you used -writeconfig, your machine description
> is (at least in theory) entirely included in the config file including
> (again in theory) the default devices.

The default devices are *not* included by in the file created by 
-writeconfig.  So I tend to thing -readconfig should not automagically 
turn on -nodefaults to avoid unpleasent surprises for users.

Devices created via -readconfig are treated like devices created via 
[device] sections in the config file.  So it doesn't matter whenever you 
configure your isa-serial device via command line or config file, in any 
case it will make qemu not create the default serial port.

cheers,
   Gerd

Re: [Qemu-devel] Re: [FOR 0.12 PATCH v3 10/21] default devices: add global cmd line option.

[Paolo Bonzini]

> > Here is my thinking: if you used -writeconfig, your machine description
> > is (at least in theory) entirely included in the config file including
> > (again in theory) the default devices.
> 
> The default devices are *not* included by in the file created by 
> -writeconfig.

Yes, that's why I wrote "at least in theory".  It doesn't now but that
would be a bug, because it makes -nodefaults another legacy option that
has to be remembered and passed again upon -readconfig.

> Devices created via -readconfig are treated like devices created via 
> [device] sections in the config file.  So it doesn't matter whenever you 
> configure your isa-serial device via command line or config file, in any 
> case it will make qemu not create the default serial port.

I was thinking about the case when you don't want at all a particular
default device.

Paolo