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Subject: Re: [Qemu-devel] Re: [PATCH] Add -no-virtio-balloon command-line
	option
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From: Markus Armbruster <armbru@redhat.com>
Date: Mon, 15 Jun 2009 20:07:42 +0200
In-Reply-To: <4A36447B.6030509@codemonkey.ws> (Anthony Liguori's message of
	"Mon\, 15 Jun 2009 07\:54\:19 -0500")
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel@nongnu.org

Anthony Liguori <anthony@codemonkey.ws> writes:

> Markus Armbruster wrote:
>> Dor Laor <dlaor@redhat.com> writes:
>>
>>   
>>> Gerd Hoffmann wrote:
>>>     
>>>>> This new option may be used to disable the virtio-balloon device.
>>>>>
>>>>>         
>>>> ACK, looks good.
>>>>
>>>> And I can drop my lazy patch which just comments out virtio-balloon
>>>> in the code ;)
>>>>       
>>> Actually, I rather have the balloon disabled by default. It's like any
>>> other pci device which needs
>>> explicit command line specification. Why consume a pci slot if not
>>> implicitly required?
>>>     
>>
>> I agree.  The command line is plenty magic without implicitly added
>> PCI devices.
>>
>> Besides, negative options -no-virtio-balloon lead to ugly
>> double-negatives like if (!no_virtio_balloon).
>>   
>
> It does no harm to add the device by default so why force the user to
> explicitly enable it?
>
> Regards,
>
> Anthony Liguori

I don't care whether it's on or off by default.  I just object to the
ugly -no-virtio-balloon.

We need to do (at least) two things to the virtio-balloon device:
suppress it, and control its PCI address.  We can do both with one
option, but it better not be called -no-virtio-balloon then.

Options controlling devices should always be extensible to accept
arbitrary name=value arguments.