Re: [Qemu-devel] [PATCH] Do not emulate a floppy drive when -nodefaults

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, May 14, 2015 at 02:45:30PM +0200, Markus Armbruster wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
> > On 14/05/2015 14:02, Markus Armbruster wrote:
> >>   It should certainly be off for pc-q35-2.4 and newer.  Real Q35 boards
> >>   commonly don't have an FDC (depends on the Super I/O chip used).
> >> 
> >>   We may want to keep it off for pc-i440fx-2.4 and newer.  I doubt
> >>   there's a real i440FX without an FDC, but our virtual i440FX is quite
> >>   unlike a real one in other ways already.
> >
> > That would break libvirt for people upgrading from 2.3 to 2.4.  So it's
> > more like pc-i440fx-3.0 and pc-q35-3.0.
> 
> What exactly breaks when?

[quote]
  * Create the FDC only if the option is "on".

  * Optional: make -drive if=floppy,... auto-enable it

    I wouldn't bother doing the same for -global isa-fdc.driveA=... and
    such.
[/quote]

Libvirt uses -global when enabling floppy devices. So since current libvirt
does not know about the new (to be created) machine type property to turn
on FDC, it will get an error using -global isa-fdc.driveA=

I'm not too bothered about this, as long as libvirt has enough advance
notice to add support for the new machine type property to enable FDC
before we change its default value to be "off". Perhaps one QEMU major
release cycle before toggling the default, to give time for new libvirt
to penetrate to distros

Regards,
Daniel
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