Re: [Qemu-devel] [PATCH 28/35] pc: propagate memory hotplug event to ACPI device

[Igor Mammedov]

On Mon, 7 Apr 2014 18:21:14 +0300
"Michael S. Tsirkin" <address@hidden> wrote:

> On Mon, Apr 07, 2014 at 04:26:02PM +0200, Igor Mammedov wrote:
> > On Mon, 7 Apr 2014 11:13:01 -0300
> > Eduardo Habkost <address@hidden> wrote:
> > 
> > > On Mon, Apr 07, 2014 at 01:07:53PM +1000, Alexey Kardashevskiy wrote:
> > > > On 04/05/2014 12:36 AM, Igor Mammedov wrote:
> > > > > Notify PIIX4_PM/ICH9LPC device about hotplug event,
> > > > > so that it would send SCI to guest notifying about
> > > > > newly added memory.
> > > > > 
> > > > > Signed-off-by: Igor Mammedov <address@hidden>
> > > > > ---
> > > > >  hw/i386/pc.c | 13 +++++++++++++
> > > > >  1 file changed, 13 insertions(+)
> > > > > 
> > > > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > > > > index 734c6ee..ee5cf88 100644
> > > > > --- a/hw/i386/pc.c
> > > > > +++ b/hw/i386/pc.c
> > > > > @@ -60,6 +60,8 @@
> > > > >  #include "acpi-build.h"
> > > > >  #include "hw/mem/dimm.h"
> > > > >  #include "trace.h"
> > > > > +#include "hw/acpi/piix4.h"
> > > > > +#include "hw/i386/ich9.h"
> > > > >  
> > > > >  /* debug PC/ISA interrupts */
> > > > >  //#define DEBUG_IRQ
> > > > > @@ -1484,6 +1486,8 @@ void qemu_register_pc_machine(QEMUMachine *m)
> > > > >  static void pc_dimm_plug(HotplugHandler *hotplug_dev,
> > > > >                           DeviceState *dev, Error **errp)
> > > > >  {
> > > > > +    Object *acpi_dev;
> > > > > +    HotplugHandlerClass *hhc;
> > > > >      Error *local_err = NULL;
> > > > >      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> > > > >      DimmDevice *dimm = DIMM(dev);
> > > > > @@ -1517,10 +1521,19 @@ static void pc_dimm_plug(HotplugHandler 
> > > > > *hotplug_dev,
> > > > >      }
> > > > >      trace_mhp_pc_dimm_assigned_slot(dimm->slot);
> > > > >  
> > > > > +    acpi_dev = (acpi_dev = piix4_pm_find()) ? acpi_dev : ;
> > ;
> > > > 
> > > > 
> > > > wow. just wow.
> > > 
> > > I had to read the C99 spec to find out if this was safe.  :-)
> > > 
> > > But I believe it is readable, I wouldn't mind keeping it that way.
> > > 
> > I'll change it to a less obscure form:
> > 
> > acpi_dev = piix4_pm_find();
> > if (!acpi_dev) {
> >     acpi_dev = ich9_lpc_find();
> > }
> 
> 
> or
> 
>     Object *piix = piix4_pm_find();
>     Object *lpc = ich9_lpc_find();
>     assert(!!piix != !!lpc);
wouldn't that assert on device_add if qemu was started without ACPI?
Exiting with error if acpi_dev == NULL seems safer here.

> 
> 
> so we verify it's one of the other.
> 


-- 
Regards,
  Igor