Re: [Qemu-devel] [RFC][PATCH 0/6] "bootonceindex" property

[Gerd Hoffmann <kraxel@redhat.com>]

On Do, 2017-03-16 at 11:46 +0200, Janne Huttunen wrote:
> On Wed, 2017-03-15 at 08:24 +0100, Gerd Hoffmann wrote:
> > >
> > > The short answer: emulating real hardware.
> > 
> > Ok, that is reason enough.
> > 
> > Adding bootonceindex everywhere doesn't look like the best plan to me
> > though.  Possibly we can pimp up bootindex in a backward-compatible
> > way?
> > Something like bootindex=<normal>[.<once>] ?
> 
> That would (likely) avoid modifying all devices, but wouldn't
> that make the 'bootindex' property a string (now: 'int32')
> and thus change the QOM API?

Good point.  I was thinking about the cmd line only where it is a string
anyway.

> I did consider making device_add_bootindex_property() to
> automatically add the new property too, but since that API
> is currently such that the _caller_ provides the name of the
> added property, it would mean that the function would need
> to generate the second name using some magic mangling rule
> and that didn't seem very nice to me.

I think the only case where this is something != "bootindex" is the
floppy controller, which has bootindexA and bootindexB for the two
drives.  So name mangling doesn't look too bad to me.  Maybe we could
just add a "first-" or "once-" prefix.  But the second bootindex still
needs to be stored somewhere in the device state struct ...

> Of course the API could
> be modified so that the caller provides two names, but then
> we are already back to modifying all relevant devices.

... so I guess there isn't really some way around that.

cheers,
  Gerd