Re: [Xen-devel] [RFC] Disable xen platform device when it is not needed.

[Shohei Fujiwara <fujiwara-sxa@xxxxxxxxxxxxxxx>]

> > Thank you for your comments.
> > 
> > On Wed, 18 Feb 2009 11:29:54 +1100
> > "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:
> > 
> > > >
> > > > I plan to create the patch to disable xen platform device when it
> > > > is not needed. Please let me know if anyone has a comment.
> > > >
> > > > Windows guest shows xen platform device as unknown
> > > > device with "!" mark in the device manager, when PV drivers are
> not
> > > > loaded. So I'd like to disable xen platform device.
> > > >
> > > > If following conditions are all true, I will disable xen platform
> > > > device. Otherwise, xen platform device will be enabled.
> > > >
> > > >     - All entries in "disk" parameter have "ioemu:" prefix in DEV
> > > field.
> > > >         Example:
> > > >         disk = [ '/var/images/guest.img,ioemu:hda,w',
> > > ',ioemu:hdc:cdrom,r'
> > > > ]
> > > >
> > > >     - All entries in "vif" parameter have "type=ioemu".
> > > >         Example:
> > > >         vif = [ 'type=ioemu, bridge=eth0', 'type=ioemu,
> bridge=eth1' ]
> > > >
> > > >     - "vscsi" parameter is not specified.
> > >
> > > I still leave my disks and network as ioemu even when using PV
> drivers,
> > > as I simply need to use the /NOGPLPV boot option to switch back to
> them.
> > 
> > When "ioemu:" or "type=ioemu" are not specified, both emulated device
> > and PV device are enabled. This is current xen's behavior.
> > 
> > So my idea does not break your usage.
> 
> Maybe I don't understand your idea, but I think you are saying that if
> ioemu is specified then the PV drivers won't work because you will
> disable the platform pci device.

I suppose your understanding is right. 

BTW, I have one question.
If you want to use the PV drivers, I don't think xen requires "ioemu" option.
Without "ioemu" option, xen will enable the emulated devices.
Why do you need "ioemu" option?

Thanks,
--
Shohei Fujiwara

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