Re: [Qemu-devel] [PATCH 03/13] iommu: Add universal DMA helper functions

[Anthony Liguori]

On 06/20/2012 04:32 PM, Michael S. Tsirkin wrote:
> On Wed, Jun 20, 2012 at 04:16:47PM -0500, Anthony Liguori wrote:
> > > diff --git a/hw/pci.h b/hw/pci.h
> > > index 7f223c0..ee669d9 100644
> > > --- a/hw/pci.h
> > > +++ b/hw/pci.h
> > > @@ -558,10 +558,16 @@ static inline uint32_t pci_config_size(const PCIDevice *d)
> > >   }
> > >
> > >   /* DMA access functions */
> > > +static inline DMAContext *pci_dma_context(PCIDevice *dev)
> > > +{
> > > +    /* Stub for when we have no PCI iommu support */
> > > +    return NULL;
> > > +}
> >
> > Why is all of this stuff static inline?
>
> Let's face it, most people don't need an MMU in their VM.
> inline stubs help make double sure we are not adding
> overhead for the sake of this niche case.

It also makes for an overly complex pci.h with no obvious performance 
justification.

Let's not prematurely optimize here.

Regards,

Anthony Liguori

>