Re: [Qemu-devel] [PATCH for-1.4 03/12] pc: Reverse pc_init_pci() compatibility logic

[Eduardo Habkost]

On Mon, Jan 21, 2013 at 04:39:24AM +0100, Andreas Färber wrote:
> Am 17.01.2013 21:59, schrieb Eduardo Habkost:
> > Currently, the pc-1.4 machine init function enables PV EOI and then
> > calls the pc-1.2 machine init function. The problem with this approach
> > is that now we can't enable any additional compatibility code inside the
> > pc-1.2 init function because it would end up enabling the compatibility
> > behavior on pc-1.3 and pc-1.4 as well.
> > 
> > This reverses the logic so that the pc-1.2 machine init function will
> > disable PV EOI, and then call the pc-1.4 machine init function.
> > 
> > This way we can change older machine-types to enable compatibility
> > behavior, and the newer machine-types (pc-1.3, pc-q35-1.4 and
> > pc-i440fx-1.4) would just use the default behavior.
> > 
> > (This means that one nice side-effect of this change is that pc-q35-1.4
> > will get PV EOI enabled by default, too)
> > 
> > It would be interesting to eventually change pc_init_pci_no_kvmclock()
> > and pc_init_isa() to reuse pc_init_pci_1_2() as well (so we don't need
> > to duplicate compatibility code on those two functions). But this will
> > be probably much easier to do after we create a PCInitArgs struct for
> > the PC initialization arguments, and/or after we use global-properties
> > to implement the compatibility modes present in pc_init_pci_1_2().
> > 
> > Signed-off-by: Eduardo Habkost <address@hidden>
> > ---
> > Cc: address@hidden
> > Cc: Michael S. Tsirkin <address@hidden>
> > Cc: Gleb Natapov <address@hidden>
> > Cc: Marcelo Tosatti <address@hidden>
> 
> Ping! mst, you handled a previous PC machine compatibility patch - can
> you ack or nack?
> 
> Eduardo, which of the following patches depend on this one? Only 12/12?

Yes, only 12/12 depend on it (it is the patch that finally introduces
the fix, on pc-1.4 only).

-- 
Eduardo