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

[Marcelo Tosatti]

On Thu, Jan 17, 2013 at 06:59:29PM -0200, Eduardo Habkost wrote:
> 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>

Reviewed-by: Marcelo Tosatti <address@hidden>