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Date: Fri, 04 Apr 2014 13:02:42 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] spapr: skip adding usb keyboard/mouse in
	case of -nodefaults
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To: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>, qemu-devel@nongnu.org, agraf@suse.com
Cc: aik@au1.ibm.com, Mark Wu <wudxw@linux.vnet.ibm.com>, qemu-ppc@nongnu.org, =?ISO-8859-15?Q?Andreas_F=E4rber?= <afaerber@suse.de>

Il 04/04/2014 07:28, Nikunj A Dadhania ha scritto:
>>> >>
>>> >> And -usb is translated to adding "pci-ohci" controller for spapr
>> >
>> > Yeah, but with -nodefaults it's better to use -device directly.
> I think there is special handling for this in vl.c
>
> bool usb_enabled(bool default_usb)
> {
>     return qemu_opt_get_bool(qemu_get_machine_opts(), "usb",
>                              has_defaults && default_usb);
> }
>
> And spapr.c uses this:
>
>     if (usb_enabled(spapr->has_graphics)) {
>         pci_create_simple(phb->bus, -1, "pci-ohci");

Sure.  However, I'm saying that it's fine for spapr to make -usb mean 
"OHCI, and also keyboard & mouse if there is a VGA card in the system".

If libvirt used "-device pci-ohci" unconditionally, it would fix the bug 
*and* it would ensure that the PCI slot of pci-ohci does not change due 
to some other unrelated reason.  So I would rather have the fix in libvirt.

Paolo