On Tue, Nov 08, 2016 at 11:37:23AM +0000, Robin Murphy wrote:
> TBH I've been pondering ripping the size stuff out of dma-iommu, as it
> all stems from me originally failing to understand what dma_32bit_pfn is
> actually for.
The point of dma_32bit_pfn is to allocate dma-address below 4G by
default. This is a performance optimization so that even devices capable
of 64bit DMA are using SAC by default instead of DAC.
Since it is the goal to share a dma-iommu implemenation between
architectures, I would rather prefer not to rip this stuff out.
Joerg
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