Re: [Qemu-devel] Re: [PATCH] Add -no-virtio-balloon command-line option

[Anthony Liguori]

Dor Laor wrote:
> Anthony Liguori wrote:
> > Markus Armbruster wrote:
> > > Dor Laor <address@hidden> 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?
>
> It consumes one of the 32 pci devices we have today. It's the same for 
> not having -usb as default
> or any other type of device. Soon we'll need pci_addr= along with it 
> anyway ;)

IMHO, -usb should be default.  It wasn't made default when it was 
introduced because it was known to be buggy.

For management tools, explicitly disabling something is easy enough.  
For humans, I think wanting features is more common than needing more 
than 32 PCI slots.

Regards,

Anthony Liguori

> Dor