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Date: Wed, 20 Jun 2012 16:38:30 -0500
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH 03/13] iommu: Add universal DMA helper
	functions
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Richard Henderson <rth@twiddle.net>, Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>, qemu-devel@nongnu.org, David Gibson <david@gibson.dropbear.id.au>

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

>